CN1756972A - Diffraction element and optical device - Google Patents
Diffraction element and optical device Download PDFInfo
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- CN1756972A CN1756972A CN 200480005691 CN200480005691A CN1756972A CN 1756972 A CN1756972 A CN 1756972A CN 200480005691 CN200480005691 CN 200480005691 CN 200480005691 A CN200480005691 A CN 200480005691A CN 1756972 A CN1756972 A CN 1756972A
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Abstract
A diffraction element having a large wavelength separating effect with a high diffraction efficiency despite its excellent mass-productivity using a simple process. A diffraction element (30) formed on a transparent substrate (301), and being protruded and recessed in section with protruded portions forming symmetrical rectangular lattices (302), wherein one cycle of a lattice is equal to or smaller than the wavelength of an incident light, and the diffraction element is used with a light entering obliquely the lattice formed surface of the diffraction element (30).
Description
Technical area
The present invention is about diffraction element and optical devices, particularly light-dividing device, is specially diffraction element that is used for exit direction light husband multiplexed communications and spectral photometry etc., change light because of the cause of wavelength and the light-dividing device that uses this element.
Background technology
There is a kind of method to be: because the light of various wavelength separates light to different direction diffraction corresponding to various wavelength, and measurement intensity separately, by the various light intensities of the different wave length measuring in the incident light like this to be comprised to separating.At this moment, in order to utilize the light that separates expeditiously, preferably diffraction light concentrates on specific diffraction progression expeditiously, as the method for wavelength separated.
In order to obtain bigger incident light and diffraction light angulation, improve the degree of freedom of optical arrangement, preferably use the diffraction grating of transmission-type.An example of the transmission-type diffraction grating that is made of resin before Fig. 7 represents.About this diffraction element, it is the not shown metal pattern that will critically form the zigzag diffraction grating of linearity, being pressed on transparency carrier 701 is on the surperficial film forming photoresist 702 of glass substrate, through after the sclerosis of ultraviolet light, carry out the demoulding, just form jagged diffraction grating 703, constituted the jagged diffraction element 70 of transmission-type.
In addition, Fig. 8 represents an example with the transmission-type class zigzag diffraction grating of the approximate ladder of ladder approximation zigzag fashion.At transparency carrier 801 is the surface of glass substrate, uses photoetching process and etching method repeatedly, forms the jagged diffraction grating 802 of class, and this diffraction grating is as the jagged diffraction element 80 of transmission-type class.
Here, in Fig. 7 and Fig. 8, the arrow of solid line is represented incident light, and dot-and-dash line is represented transmitted light, and dotted line is represented-1 order diffraction light.
In the above-mentioned former example, in order to make transmission-type zigzag diffraction grating high diffraction efficiency is arranged, need make the refringence of exiting side media such as grating material and air and the defined phase differential of product of the grating degree of depth is the approximate wavelength degree.On the other hand, become big in order to make the angle corresponding to the separation of wavelength, the cycle of grating is the smaller the better.Therefore, need make cycle that is shaped as grating of zigzag diffraction grating little and correspond to the big shape of the defined aspect ratio of ratio (D/T) of the period T of grating with the depth D of grating.
Summary of the invention
But the big jagged grating of aspect ratio is very difficult on making, and in the process of making of resin, can have the problems such as transfer printing, liftability of restriction in the metal pattern processing and resin.Therefore, the problem of appearance is, corresponding desired wavelength has big separating power and light had the throughput rate of diffraction grating of high utilization ratio low, problems such as price height.
In addition, when using resin material, have the problem aspect the reliabilities such as to occur deterioration at high temperature and hot and humid element down, have the problem that in the environment of restriction, to use element.
On the other hand, about the jagged diffraction grating of class, though can in a large number production good reliability and the high cheap component of throughput rate, need carry out the further processing of sectionalization of cycle with grating, as the jagged diffraction grating of class, has the problem of the making difficulty of little element of cycle.And, because the warpage that the error when making causes is big, make characteristic degradation, existing has usury with the diffraction grating of the efficient not high problem of rate that manufactures a finished product to light.
For the example before the whichever, when in 0 degree incident (the surperficial incident of light perpendicular elements), because diffraction efficiency significantly reduced when the known cycle when grating was about 2 times of wavelength, also exist so simultaneously to be difficult to take into account high-diffraction efficiency and to utilize minor cycleization (about 2 times etc.) and the big separation problem of corresponding light wavelength realization.
The present invention is in view of above-mentioned actual conditions, and purpose is: provide light is had a high utilization ratio and corresponding wavelength realize big separation, have the good optical system the configuration degree of freedom, can produce and have the diffraction element of good reliability and temperature characterisitic in a large number.
The invention provides a kind of diffraction element, this diffraction element has following feature: the surface formed grating of thin layer that form or that form on substrate that is included in substrate, be that its cross section is that the upper surface of concavo-convex and protuberance comes down to grating smooth, the protuberance symmetry, this diffraction element uses like this, the one-period that is grating equals the incident light wavelength in fact, and the grating of light oblique incidence diffraction element forms face.
In addition, the above-mentioned diffraction element that provides is characterized in that: in the shared ratio of protuberance and recess, the ratio of protuberance is more than or equal to the ratio of recess within the one-period of above-mentioned grating.
In addition, the above-mentioned diffraction element that provides is characterized in that: the wall that forms the protuberance of above-mentioned grating tilts, and the shared ratio in grating protuberance upper end is less than the shared ratio in grating protuberance bottom within one-period.
In addition, the above-mentioned diffraction element that provides is characterized in that: at the stacked one or more layers of optical material different with recess of the protuberance at least of above-mentioned diffraction element.
The above-mentioned diffraction element that provides is characterized in that: above-mentioned optical material is from TiO
2, SiO
2, Ta
2O
5, Al
2O
3The middle material of selecting.
In addition, the above-mentioned diffraction element that provides is characterized in that: use transparency carrier as aforesaid substrate, the rete on transparency carrier forms the protuberance of grating, and the refractive index of the protuberance of grating is higher than the refractive index of transparency carrier.。
The above-mentioned diffraction element that provides is characterized in that: the thin layer that forms on transparency carrier is from SiO
2, TiO
2, Ta
2O
5, Si
3N
4, select a kind of rete in this class material of Si, or the rete that constitutes of the potpourri of this class material as principal ingredient.
A kind of diffraction element is provided, it is characterized in that: with other optical element, stacked formation is integrated on a face of above-mentioned diffraction element.
In addition, the using method of the diffraction element that is provided, it is characterized in that: above-mentioned diffraction element be included in form on the substrate surface or substrate on formed grating on the thin layer that forms, the upper surface that is its cross section concave-convex surface and protuberance is smooth in fact, the grating of protuberance symmetry, using method is that the one-period of grating equates in fact with the incident light wavelength, and the grating of light oblique incidence diffraction element forms face.
In addition, the using method of the above-mentioned diffraction element that is provided is characterized in that: relatively perpendicular to the diffraction element normal to a surface, the incident angle during above-mentioned smooth oblique incidence is in 15～80 ° scope.
In addition, the optical devices that provided is characterized in that: used above-mentioned diffraction element.
And the light-dividing device that is provided is characterized in that: above-mentioned optical devices are a kind of light-dividing devices, and with the substrate of transparency carrier as above-mentioned diffraction element, above-mentioned diffraction element uses as the transmission-type element.
Description of drawings
Fig. 1 represents a kind of side view of constructing example of diffraction element of the present invention.
Fig. 2 represents the side view of the another kind structure example of diffraction element of the present invention.
Fig. 3 represents the side view of the another kind structure example of diffraction element of the present invention.
Fig. 4 represents the figure of the different diffraction characteristic of diffraction element of the present invention when protuberance is formed with multilayer film and when not forming multilayer film.
Fig. 5 represents the figure of the diffraction characteristic that produces owing to the different polarization direction of incident light about diffraction element of the present invention.
Fig. 6 represents the figure of the diffraction characteristic that produces owing to the ratio of different recesses and protuberance about diffraction element of the present invention.
Fig. 7 represents a kind of side view of constructing example of former diffraction element.
Fig. 8 represents the side view of the another kind structure example of former diffraction element.
Fig. 9 represents the side view of the another kind structure example of diffraction element of the present invention.
Figure 10 represents about the figure of diffraction element of the present invention owing to the diffraction characteristic of the different polarization direction of incident light.
Figure 11 represents the side view of the another kind structure example of diffraction element of the present invention.
Figure 12 represents the side view of the another kind structure example of diffraction element of the present invention.
Figure 13 represents that diffraction element of the present invention changes the figure of the diffraction characteristic example that produces owing to the cone angle of grating protuberance wall.
Figure 14 represents that other diffraction element of the present invention changes the figure of other examples of diffraction characteristic that produce owing to the cone angle of grating protuberance wall.
Embodiment
The invention relates to cross section that surface with substrate forms and be concavo-convex, the protuberance grating diffration element for symmetry, the cycle of grating is equal to or less than the incident light wavelength.In addition, be for the formation face of grating only oblique incidence and the diffraction element that uses.
In addition, the cross section is concavo-convex grating, also can be formed on the thin layer upper surface on the substrate.As the material of the thin layer on the substrate, preferably good etching characteristic to be arranged, can adopt SiO
2, TiO
2, Ta
2O
5, Si
3N
4, Si etc. is as the material of principal ingredient or their potpourri.Because diffraction element has such structure, the diffraction element that can realize easy technology and good throughput rate, have high diffraction efficiency and big wavelength separated effect.In order to have big wavelength separated effect, use the diffraction grating of using as beam split more satisfactory.
Here, the cycle of so-called grating equates in fact with the incident light wavelength, be meant the cycle incident wavelength ± 45% in.That is to say that the cycle is within 0.55～1.45 times scope of wavelength.If this ± 45% in, then suitably select incident angle just only to produce specific diffraction light, can not diminish effect of the present invention.In addition, so-called light is meant for the normal perpendicular to element surface that for the formation face oblique incidence of grating angulation particularly under 25 to 65 ° situation, can reach effect of the present invention fully between 15 to 80 °.
About the cross sectional shape of the protuberance of the symmetry of the jog of diffraction grating, so long as rectangle or trapezoidal etc. can, though be which kind of shape all has effect of the present invention, approximate rectangular is more satisfactory on making.
The substrate of using about diffraction element, as transparent substrate, the substrate that can make with quartz glass, glass, silicon, polycarbonate etc.In these types, the substrate that quartz glass, glass are made is more satisfactory on the permanance this respect.In addition, in the structure as the reflection-type diffraction element, it is comparatively desirable to form the reflectance coating that is made of metal or multilayer film on diffraction grating, except above-mentioned transparency carrier, also can promptly for example use crystallized glass, pottery etc. with opaque substrate.
Below be the present invention who is shaped as rectangle with reference to drawing explanation protuberance.
Fig. 3 represents the side view of a kind of configuration example of transmissive diffraction element of the present invention.On transparency carrier 301, the cycle of the grating that the method for usefulness photoetching process and dry etching forms has constituted diffraction grating 30 less than the rectangle diffraction grating 302 of lambda1-wavelength.Cycle for grating is the diffraction grating (correctly being its length direction) of P, is the incident light of λ with the wavelength that is angled i with normal direction, produces the diffraction light of m level in the direction that by (formula 1) defined angle of diffraction is θ.By (formula 1) as can be known, when the corresponding diffraction grating 302 of light is vertical incidence, there be not the diffraction light of cycle less than the diffraction grating of wavelength.But, keeping limited angle, also,, also have the diffraction light of progression even under the situation of the diffraction grating of little length of cycle promptly when light during from oblique direction incident.Therefore as can be known, even the structure upper convex portion has symmetric shape, but can represent asymmetrical diffraction characteristic.
Sin (θ)+sin (i)=m λ/P ... (formula 1)
Utilize the effect of this oblique incidence, go up the rectangle diffraction grating that is easy to symmetry, also can obtain sufficiently high diffraction efficiency and big angle of diffraction even make.Now lift an example: for cycle of grating is that the degree of depth of 1000nm (width of recess and protuberance is 500nm), grating is the diffraction grating of 2300nm, when the normal incidence angle is about 50 °, according to calculating, the correlativity of-1 order diffraction efficient and wavelength is shown in the bullet that is connected with solid line among Fig. 4.As can be known to the incident light of the straight line polarization of grating parallel polarization, greater than the 1520nm in cycle of grating in the scope of 1620nm, light intensity concentrates on-1 order diffraction light, expression has high-diffraction efficiency.
In order further to improve diffraction efficiency, reduce the correlativity of wavelength, form suitable multi-layer film structure at the protuberance of grating and can reach this effect.Now lift an example: with the TiO of high-index material
2SiO with low-index material
2When four tunics were formed at the top of the protuberance of grating, the correlativity of its diffraction efficiency and wavelength was shown in the white round dot that with dashed lines among Fig. 4 is connected.The same high-diffraction efficiency is arranged in all band zone as shown in Figure 4.
That is to say that be preferably in the protuberance and the stacked different above optical material of one deck of recess of grating, this can improve diffraction efficiency.Optical material is except above-mentioned TiO
2, SiO
2In addition, can also enumerate Ta
2O
5, Al
2O
3Deng.
The another one example: the cycle for grating is that 1500nm, the degree of depth are the diffraction grating of 3000nm, is about 30 when spending at incident angle, and the correlativity of diffraction efficiency and wavelength as shown in Figure 5.Connect the curve that bullet became by solid line among Fig. 5, represented to the diffraction efficiency of the rectilinearly polarized light of grating parallel polarization, the white round dot that is connected by dotted line is represented the diffraction efficiency with the rectilinearly polarized light of grating vertical polarization.As shown in Figure 5, for any polarized light high diffraction efficiency is arranged all.
In the example shown in Figure 5, though for any orthogonal straight lines polarized light high diffraction efficiency is arranged all, approaching more near the 1520nm of short wavelength zone and the 1620nm of long wavelength zone, the trend that increases more of diffraction efficiency is then arranged.This difference is reduced, adjust the recess of formation grating and the ratio of protuberance and can reach this effect.Fig. 6 represents is the shared different proportion of protuberance and poor with the diffraction grating diffraction efficiencies in the scope of wavelength from 1520nm to 1620nm, two crossed polarized lights of depth optimization in the one-period of grating.As shown in Figure 6, the diffraction efficiency of two crossed polarized lights poor, the ratio value shared when protuberance is suppressed in over half significantly.So also can obtain the very little diffraction grating of correlativity of incident polarized light by adjusting protuberance in the grating shared ratio in one-period.
Reduce difference for the diffraction efficiency of orthogonal straight lines polarized light, be about in the ratio of protuberance that keeps the grating upper end and recess on 1 the basis, also can reach this effect to the vertical line angulation (hereinafter referred to as cone angle) of substrate surface by adjusting grating protuberance wall.Figure 13 represents is that the grating cycle that forms on the surface of the quartz glass substrate identical with Fig. 6 is that 1500nm, the diffraction grating degree of depth are the diffraction grating of 3600nm, in the scope of wavelength from 1520nm to 1570nm, and the diffraction efficiency of two crossed polarized lights poor.
As shown in Figure 13, the difference of the diffraction efficiency of two crossed polarized lights changes because of above-mentioned cone angle, adopts the above cone angle of 3 degree, when ideal is about the cone angle of 4 degree, can significantly improve.Like this, by adjusting the cone angle of grating sidewall, also can obtain the diffraction grating very little with the correlativity of incident polarized light.
Such adjustment has suppressed the correlativity with polarized light, has also suppressed the difference of the diffraction characteristic that the degree of depth owing to grating causes, thereby has also had the effect that improves yield rate in manufacturing process simultaneously.
That is to say, for the ratio of the shared ratio protuberance of the protuberance in the one-period of diffraction grating and recess ratio more than or equal to recess, also promptly 0.5 and more than, then can dwindle diffraction efficiency poor of two crossed polarized lights, so more satisfactory.In addition, if make the wall of the protuberance that forms diffraction grating that inclination be arranged, when the shared ratio of the protuberance of grating in one-period upper end during, can dwindle diffraction efficiency poor of two crossed polarized lights, so more satisfactory smaller or equal to the shared ratio of the protuberance of grating bottom.
Further reduce the cycle of diffraction grating, it is big that the variation of the separation angle of corresponding wavelength becomes, though the effect that improves the wavelength resolution ratio is arranged, but the cycle of grating as above-mentioned example when 1500nm is reduced to 1000nm, incident polarization light direction and the difference of the diffraction efficiency that produces has more significantly tendency.
Therefore, even adjust grating protuberance shared ratio in the cycle of grating, though certain effect is arranged not enough.In the cycle of grating is under the situation of 1000nm, reduce the incident polarization light direction and the diffraction efficiency that produces poor, uses than the constituent material of the high material of the refractive index of the transparency carrier of film forming on transparency carrier as the grating protuberance, can reach this effect.
Figure 10 represents the diffraction efficiency of corresponding various incident polarization light directions and the correlativity of wavelength.On quartz glass substrate the protuberance of grating and recess be in equal proportions carry out processing situation following time characteristic shown in white round dot.Connect curve and the with dashed lines that white round dot becomes with solid line among Figure 10 and connect the curve that white round dot becomes, represent the direction of corresponding various gratings, also be the characteristic to parallel and vertical polarized light of the length direction of grating.
On the other hand, among Figure 10, has characteristic under the situation of grating protuberance that refractive index is about 2 material shown in bullet in film forming on the transparency carrier, connect curve and the with dashed lines that bullet became with solid line among Figure 10 and connect the curve that bullet became, expression is to the characteristic of the parallel and vertical polarized light of the direction difference of grating.As shown in Figure 10, reduced poor to the diffraction efficiency of incident polarization light direction.
It is identical with above-mentioned example that Figure 13 represents, having under the situation of grating protuberance that refractive index is about 2 material of film forming on the transparency carrier, the protuberance of grating upper end and the ratio of recess remain on be roughly 1 constant, by adjusting the cone angle of grating protuberance, can reduce poor to the diffraction efficiency of direction of polarized light.Figure 14 has represented that on the transparency carrier refractive index of film forming is about the grating protuberance of 2 material, in the scope of wavelength from 1520nm to 1570nm, and the diffraction efficiency of the direction of polarized light of two quadratures poor.As shown in Figure 14: have under the situation of grating protuberance that refractive index is approximately 2 material, be approximately 6 when spending, also can improve diffraction efficiency poor of two cross polarization light directions significantly at cone angle.
In addition, from above-mentioned all examples as can be known, incident ray and diffraction light roughly are concerning the diffraction grating plane of transmission-type under the situation of relation of mirror image, also are under incident angle and the angle of diffraction situation about equally, just can obtain high diffraction efficiency.This configuration can be called with the configuration under the situation of the diffraction grating of so-called littrow arrangement, incident ray and the stacked transmission-type of diffracted ray of reflection-type diffraction grating.
In addition, generally for optical element,, can utilize optical multilayer to form clad in order to reduce the reflection at interface.Under the situation of the very big diffraction grating of the aspect ratio shown in above-mentioned example, owing to the different drawbacks such as shape deterioration that cause of film forming characteristics of recess and protuberance are a lot, the result in most cases causes the utilization ratio of light to reduce.Diffraction grating by making on the substrate that adds low reflection clad in advance can improve transmissivity.At this moment, though the sidepiece of grating and bottom do not add the clad of low reflection, the shape of grating does not worsen, and can only add the clad of low reflection on the top of grating.
By adopting structure of the present invention, can utilize the transmission-type diffraction grating that incident light and diffraction light are fully separated to realize having easy processing technology and big wavelength separated effect and light being had the beam split diffraction grating of usury with efficient.Utilize this structure, can realize good reliability, the branch optical diffraction element that throughput rate is high, but also can realize cheap beam splitting system.In addition, owing to can use transmission configuration, the design of beam splitting system there has been very big degree of freedom.
About the diffraction grating figure of diffraction element of the present invention, owing to can use photomask to wait to make, making the diffraction grating figure be not limited only to rectilinear form can also be curve shape for example.Utilize this curve shape, can also add and on photodetector, focus on the such lens function of diffraction light.In addition, by using large-area wafer technique, the optical element that can make phase-plate etc. have other functions is layered on the diffraction element, can further improve function, carry out compoundization.
As the optical element of stacked other, can enumerate have limited aperture, the optical element of function such as aberration correction, lens effect, beam shaping, polarized light conversion, phase place adjustment, intensity adjustment.Stacked optical element preferably can be applicable to the large tracts of land wafer technique of diffraction element, liquid crystal cell, multilayer film element etc.
That is to say, be preferably in stacked other optical element on the face of above-mentioned diffraction element, form integratedly, other optical function can be attached on the diffraction element, to improve function.
About diffraction grating of the present invention, be to substrate for example be glass substrate itself or on glass substrate the inorganic material of film forming be processed into.Particularly the viewpoint from omitting film formation process and not having the interface between film and the substrate preferably directly forms grating on substrate.That is to say, can be very ideally have at a high speed and evenly the quartz of etching characteristic be directly processing on the glass substrate, and from reliability and the viewpoint of property, the preferably glass plate of quartzy system in batches.
In addition, for the variation of the diffraction direction that suppresses to cause, importantly to be controlled the linear expansion coefficient of employed substrate owing to variation of temperature.Preferably use the transparency carrier of optimal linear expansion coefficient, can obtain having the element of good temperature characteristics like this.In this case, can directly process the surperficial of transparency carrier of optimal linear expansion coefficient, the inorganic material that can also will have good etching characteristic on the transparency carrier of optimal linear expansion coefficient forms rete.
As an example is exactly the glass substrate material that has suppressed linear expansion coefficient, and it can use with the quartz glass that has mixed Ti, Al
2O
3-LiO
3-SiO
2In the glass etc. that is principal ingredient, but the influence that particularly preferably the substrate temperature change procedure in the technological process is produced seldom and the quartz glass that has mixed Ti with good etching carry out direct substrate processing.
In addition, described when the big grating of aspect ratio forms as above-mentioned example, the outer part of element does not also have to process, and this breakage for photoresist mask that prevents work in-process and grating material is more satisfactory.
About diffraction element of the present invention, if enough improve the diffraction grating of the minor cycle of wavelength resolution ratio by special increase angle of diffraction, can obtain significant effect, the cycle of diffraction grating and centre wavelength element about equally particularly, or the cycle (spacing) less than the element in the scope of centre wavelength, very big effect is then arranged.
Use the diffraction element of the invention described above can constitute multiple different optical devices.These optical devices are if use the characteristics such as dichroism of diffraction element of the present invention, and then no matter which kind of optical devices can.
In addition, the substrate of above-mentioned diffraction element is to adopt transparency carrier, and diffraction element is to constitute light-dividing device as the transmission-type element, but because diffraction element of the present invention has big wavelength separated effect, the separation angle of the diffraction light of incident light and transmission is very big, therefore not restriction in configuration.
So-called light-dividing device of the present invention for example has in the optical communication of being used in the detecting device as wavelength division multiplexing communications., under the situation of flashlight by same transmission optical fiber of the different wave length of 1620nm, just must be separated into each wavelength and measure the signal intensity of each different wavelengths of light at 1520nm.Utilize the effect of diffraction element of the present invention from the light that transmits the optical fiber outgoing, corresponding different wave length transmits to different direction diffraction, to the element incident of different reception light, just can measure the signal intensity of each wavelength.And, because corresponding each wavelength has different transmission approach, therefore can adjust the different intensity and the phase place of each wavelength.Under the situation of the element that uses reflection-type, in order to obtain the utilization ratio of high light, general is adopt incident light and reflection diffracting light approaching be called littrow arrangement.Restriction to the configuration of incident optical and detecting device, and the diffraction element of transmission-type of the present invention, not only can realize with reflect littrow arrangement identical light is had high utilization ratio, but also have advantage such as make that incident light and diffraction light angulation are big, the restriction in the configuration is less.
It below is specific embodiment.
Fig. 1 represents the side view of the beam split diffraction grating structure of present embodiment.In the present embodiment, the quartz glass substrate that with thickness is 2.0mm is as transparency carrier 101, the one side TiO of transparency carrier
2And SiO
2Make incident angle is four layers of minimum antireflection film 102 of reflection of light rate of 50 degree.With photoengraving and dry etching technology it is formed rectangular-shaped diffraction grating then.That is to say, at first after removing by etching corresponding to the part of the antireflection film of grating recess, the working depth of implementing quartz glass is the etching of 900nm, has formed that the grating of the multilayer film cycle is arranged on the protuberance of quartz glass is the diffraction grating 103 of the rectangle of 1000nm.The width ratio of recess and protuberance is 1: 1.
In addition, transparency carrier 101 with the opposite one side of face that forms rectangle diffraction grating 103, form four layers of antireflection film 104 with above-mentioned same incident lights to 50 degree.Then, with cast-cutting saw transparency carrier 101 being cut into the rectangle of 15mm * 10mm, promptly is diffraction element 10.
Side from the rectangle diffraction grating 103 of diffraction element 10, grating is a parallel polarized light relatively, wavelength is 1520,1570 and the light of 1620nm when being 50 ° of incidents with outside incident angle, and corresponding respectively each wavelength has 92,93 and 91% high diffraction efficiency.In addition, because incident light wavelength difference, the exit direction of diffraction light becomes 49,54 and 59 degree respectively, and the light of three kinds of wavelength just can separate fully.Represent incident light with solid arrow respectively among Fig. 1, dot-and-dash line is represented transmitted light, and dotted line is represented-1 order diffraction light.
Fig. 2 represents the side view of the branch optical diffraction element structure of present embodiment.In the present embodiment, be that the quartz glass substrate of 2.0mm is as transparency carrier 201 with thickness.Scribble photoresist on the transparency carrier 201, adopting peristome is the photoetching process of the photomask of expression not among 1/3 figure in grating cycle, has formed protuberance and recess width ratio and be 2: 1 photoresist mask.Then, forming the degree of depth with dry etching technology is the rectangle diffraction grating of 3400nm.That is to say that the cycle that has formed grating is that 1500nm, protuberance width are that 1000nm, recess width are that the working depth of 500nm, quartz glass is the rectangle diffraction grating 202 of 3600m.
Secondly, at the another side opposite with the formation face with rectangle diffraction grating 202 of transparency carrier 201, the reflection of incident light that forms 30 degree prevents film 203.Then, with cast-cutting saw transparency carrier 201 being cut into the rectangle of 10mm * 6mm, promptly is diffraction element 20.
From a side of the rectangle diffraction grating 202 of diffraction element 20, wavelength is 1520,1570 and the light of 1620nm when being 30 ° of incidents with outside incident angle, and grating is a parallel polarized light relatively, and the diffraction efficiency of each wavelength is respectively 92,92 and 92%.Be orthogonal polarized light for relative grating on the other hand, be respectively 95,92 and 89%, to no matter being the variation of lambda1-wavelength or the variation of polarization of incident light direction all has high diffraction efficiency.And because the lambda1-wavelength difference, the exit direction of diffraction light becomes 31,33,35 degree respectively, and the light of three kinds of wavelength just can separate fully.Represent incident light with solid arrow respectively among Fig. 2, dot-and-dash line is represented transmitted light, and dotted line is represented 1 order diffraction light.
Fig. 9 represents the side view of the branch optical diffraction element structure of present embodiment.In the present embodiment, be that the colourless transparent plate glass substrate of 2.0mm is as transparency carrier 901 with thickness.It is the Ta of 1.3 μ m that the one side of transparency carrier forms thickness with sputtering method
2O
5The SiO of rete and 0.35 μ m
2 Rete 5 is optionally removed rete with photoetching and dry etching technology then, forms by Ta
2O
2Rete 903 and SiO
2The rectangular-shaped diffraction grating 904 that rete 902 constitutes.At this moment, the photomask opening of not representing by the figure that optimizes exposure usefulness, adjust the ratio of light transmission part and lightproof part, make the grating jog with respect to the ratio in grating cycle be 6: 4, also promptly form under the situation of recess of the corresponding 400nm of protuberance of 600nm.
Secondly, at the opposite another side of the formation face with rectangle diffraction grating 904 of transparency carrier 901, the reflection of incident light that similarly forms 50 degree with above-mentioned example prevents film 905.Then, with cast-cutting saw transparency carrier 901 being cut into the rectangle of 5mm * 10mm, promptly is diffraction element 90.
From a side of the rectangle diffraction grating 904 of diffraction element 90, grating is 1520,1570 and the light of 1620nm when being 50 ° of incidents with outside incident angle for the parallel polarization light wavelength relatively, and corresponding each wavelength has 93,94 and 92% high-diffraction efficiency respectively.In addition, be the light of same 1520,1570 and 1620nm of vertical polarization for relative grating, 91,92 and 91% high-diffraction efficiency is also arranged respectively.
In addition, because the lambda1-wavelength difference, the exit direction of diffraction light becomes 49,54 and 59 degree respectively, and the light of three kinds of wavelength just can separate fully.Represent incident light with solid arrow respectively among Fig. 9, dot-and-dash line is represented transmitted light, and dotted line is represented-1 order diffraction light.
Figure 11 represents the side view of the branch optical diffraction element structure of present embodiment.In the present embodiment, be that the quartz glass substrate of 2.0mm is as transparency carrier 1101 with thickness.It is the Ta of 1300nm that the one side of transparency carrier forms thickness with sputtering method
2O
5The SiO of rete and 450nm
2Rete.Optionally rete is removed with photoetching and dry etching technology then, formed by Ta
2O
5Rete 1103 and SiO
2The rectangular-shaped diffraction grating 110 that rete 1102 constitutes.At this moment, photomask opening and etching condition that the figure that uses by the optimization printing opacity does not represent the wall of diffraction grating protuberance is tilted, thereby the formation cycle are the grating that cone angle is arranged 1104 of 1000nm.The protuberance of the grating upper end of the diffraction grating of making and the width ratio of recess are approximately 1: 1, and the wall cone angle of grating protuberance is about 6 degree.
Secondly, at the opposite another side of the formation face with rectangle diffraction grating 1104 of transparency carrier 1101, the reflection of incident light that similarly forms 50 degree with above-mentioned example prevents film 1105.Then, with cast-cutting saw transparency carrier 1101 being cut into the rectangle of 15mm * 10mm, promptly is diffraction element 110.
From a side of the rectangle diffraction grating 1104 of diffraction element 110, grating is 1520,1545 and the light of 1570nm when being 50 ° of incidents with outside incident angle for the parallel polarization light wavelength relatively, and corresponding each wavelength has 94,95 and 94% high-diffraction efficiency respectively.In addition, be the light of same 1520,1545 and 1570nm of orthogonal polarized light for relative grating, 95,95 and 95% high-diffraction efficiency is also arranged respectively.
Figure 12 represents the side view of the branch optical diffraction element structure of present embodiment.In the present embodiment, be that the quartz glass substrate of 2.0mm is as transparency carrier 1201 with thickness.Painting photoresist on the transparency carrier 1201 has used the photomask of not representing among the figure, adopts photoetching process, has formed the photoresist mask.Then, forming the degree of depth with dry etching technology is that cycle of 3600nm, grating is the diffraction grating 1202 of 1500nm.At this moment, by optimizing photomask opening and the etching condition that figure that printing opacity uses does not represent, for the wall of diffraction grating protuberance has inclination, the grating 1202 of cone angle is arranged.The protuberance of the grating upper end of the diffraction grating of making and the width ratio of recess are approximately 1: 1, and the wall taper angle theta of grating protuberance is about 4 degree.
Secondly, at the opposite another side of the formation face with rectangle diffraction grating 1202 of transparency carrier 1201, the reflection of incident light that forms 30 degree prevents film 1203.Then, with cast-cutting saw transparency carrier 1201 being cut into the rectangle of 10mm * 6mm, promptly is diffraction element 120.
From rectangle diffraction grating 1,202 one sides of diffraction element 120, relatively grating is 1520,1545 and the light of 1570nm when being 30 ° of incidents with outside incident angle for the parallel polarization light wavelength, and corresponding each wavelength has 95,96 and 95% high-diffraction efficiency respectively.In addition, be the light of same 1520,1545 and 1570nm of orthogonal polarized light for relative grating, 95,95 and 94% high-diffraction efficiency is also arranged respectively.
Industrial practicality
As described above, diffraction element of the present invention is to have simultaneously tool of simple technology, good batch The branch optical diffraction element that high diffraction efficiency and big wavelength separated effect are arranged. And, diffraction of the present invention unit Part can realize having the diffraction element of good reliability, properties of polarized light etc.
Claims (12)
1. a diffraction element is characterized in that: comprise
At the surface of the substrate formed grating of rete that form or that on substrate, form, be that its cross section is concavo-convex, and the upper surface of protuberance comes down to grating smooth, the protuberance symmetry, described diffraction element uses like this, the one-period that is the grating of diffraction element equals the incident light wavelength in fact, and the grating of light oblique incidence diffraction element forms face.
2. diffraction element as claimed in claim 1 is characterized in that:
In the shared ratio of protuberance and recess, the ratio of protuberance is more than or equal to the ratio of recess within one-period.
3. diffraction element as claimed in claim 1 or 2 is characterized in that:
The wall that forms the protuberance of described grating tilts, and the shared ratio in grating protuberance upper end is smaller or equal to the shared ratio in grating protuberance bottom within one-period.
4. as claim 1,2 or 3 described diffraction elements, it is characterized in that:
Described diffraction element is at least at different one deck of the stacked protuberance of protuberance and recess and the optical material more than one deck.
5. diffraction element as claimed in claim 4 is characterized in that:
Described optical material is from TiO
2, SiO
2, Ta
2O
5, Al
2O
3The middle material of selecting.
6. as any described diffraction element of claim 1 to 5, it is characterized in that:
Use transparency carrier as described substrate, the film forming layer on transparency carrier forms the protuberance of grating, and the refractive index of the protuberance of grating is higher than the refractive index of transparency carrier.
7. diffraction element as claimed in claim 6 is characterized in that:
The rete that forms on transparency carrier is from SiO
2, TiO
2, Ta
2O
5, Si
3O
4, select a kind of rete or rete of constituting of the potpourri of these materials as principal ingredient in this class material of Si.
8. diffraction element is characterized in that:
Be stacked with other optical elements on a face of any described diffraction element of claim 1 to 7, form integrated.
9. the using method of a diffraction element is characterized in that:
Described diffraction element is included in the surface formed grating of rete that form or that form of substrate on substrate, its cross section is concavo-convex and comes down to grating smooth, the protuberance symmetry above the protuberance, the using method of diffraction element is: the one-period of grating equals the incident light wavelength in fact, and the grating of light oblique incidence diffraction element forms face.
10. the using method of diffraction element as claimed in claim 9 is characterized in that:
The normal of relative diffraction element Surface Vertical, the incident angle of described light when oblique incidence is in 15～80 ° scope.
11. optical devices is characterized in that:
Used any described diffraction element as claim 1 to 8.
12. a light-dividing device is characterized in that:
Optical devices as claimed in claim 11 are light-dividing devices, and with the substrate of transparency carrier as described diffraction element, described diffraction element is used as the transmission-type element.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP068214/2003 | 2003-03-13 | ||
| JP2003068214 | 2003-03-13 | ||
| JP078133/2003 | 2003-03-20 |
Publications (2)
| Publication Number | Publication Date |
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| CN1756972A true CN1756972A (en) | 2006-04-05 |
| CN100386653C CN100386653C (en) | 2008-05-07 |
Family
ID=36689385
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CNB2004800056919A Expired - Lifetime CN100386653C (en) | 2003-03-13 | 2004-03-12 | Diffraction element and optical device |
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| CN (1) | CN100386653C (en) |
Cited By (10)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN102269833A (en) * | 2010-05-13 | 2011-12-07 | 精工爱普生株式会社 | Spectrometry apparatus, detection apparatus, and method for manufacturing spectrometry apparatus |
| JP2013024625A (en) * | 2011-07-19 | 2013-02-04 | Seiko Epson Corp | Spectroscopic instrument, detector and method for manufacturing spectroscopic instrument |
| CN103364855A (en) * | 2013-07-01 | 2013-10-23 | 中国科学院上海光学精密机械研究所 | Polarization independent 1550 nanometer high-diffraction-efficiency double-layer transmission grating |
| CN102016658B (en) * | 2008-05-05 | 2014-12-10 | 纳诺科普有限公司 | Light manipulation arrangement |
| CN109655951A (en) * | 2017-10-11 | 2019-04-19 | 上海矽安光电科技有限公司 | A kind of polarization uncorrelated broadband reflection grating of 1550 nano wavebands of optic communication |
| CN110431118A (en) * | 2017-01-05 | 2019-11-08 | 奇跃公司 | Pass through the patterning of the glass of high refractive index of plasma etching |
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| CN111829565A (en) * | 2020-06-30 | 2020-10-27 | 沈阳中光电子有限公司 | Code disc, encoder and assembling method |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0527108A (en) * | 1991-07-18 | 1993-02-05 | Ishikawajima Harima Heavy Ind Co Ltd | Production of laminar grating |
| JP3407477B2 (en) * | 1995-06-08 | 2003-05-19 | 松下電器産業株式会社 | Phase grating, manufacturing method thereof, and optical encoder |
| US5907436A (en) * | 1995-09-29 | 1999-05-25 | The Regents Of The University Of California | Multilayer dielectric diffraction gratings |
| DE19652563A1 (en) * | 1996-12-17 | 1998-06-18 | Heidenhain Gmbh Dr Johannes | Photoelectric position measuring device |
| JPH11183249A (en) * | 1997-12-24 | 1999-07-09 | Ando Electric Co Ltd | Spectroscope |
| EP1090315A1 (en) * | 1999-03-22 | 2001-04-11 | Mems Optical, Inc. | Diffractive selectively polarizing beam splitter and beam routing prisms produced thereby |
| JP4157654B2 (en) * | 1999-08-23 | 2008-10-01 | 独立行政法人 日本原子力研究開発機構 | Conical diffraction oblique incidence spectrometer and diffraction grating for the spectrometer |
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2004
- 2004-03-12 CN CNB2004800056919A patent/CN100386653C/en not_active Expired - Lifetime
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| CN102269833A (en) * | 2010-05-13 | 2011-12-07 | 精工爱普生株式会社 | Spectrometry apparatus, detection apparatus, and method for manufacturing spectrometry apparatus |
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| JP2013024625A (en) * | 2011-07-19 | 2013-02-04 | Seiko Epson Corp | Spectroscopic instrument, detector and method for manufacturing spectroscopic instrument |
| CN103364855A (en) * | 2013-07-01 | 2013-10-23 | 中国科学院上海光学精密机械研究所 | Polarization independent 1550 nanometer high-diffraction-efficiency double-layer transmission grating |
| CN110431118A (en) * | 2017-01-05 | 2019-11-08 | 奇跃公司 | Pass through the patterning of the glass of high refractive index of plasma etching |
| CN110431118B (en) * | 2017-01-05 | 2023-10-27 | 奇跃公司 | Patterning of high refractive index glass by plasma etching |
| CN109655951A (en) * | 2017-10-11 | 2019-04-19 | 上海矽安光电科技有限公司 | A kind of polarization uncorrelated broadband reflection grating of 1550 nano wavebands of optic communication |
| CN113366365A (en) * | 2018-12-18 | 2021-09-07 | 交互数字Ce专利控股公司 | Optical manipulation device |
| CN111708175A (en) * | 2020-06-29 | 2020-09-25 | 国科光芯(海宁)科技股份有限公司 | Structured light projection device |
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| CN100386653C (en) | 2008-05-07 |
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