CN106062600B

CN106062600B - Light beam combiner and chip type multi-wavelength laser light source

Info

Publication number: CN106062600B
Application number: CN201580006643.XA
Authority: CN
Inventors: 成泽润
Original assignee: Photon R&d Inc
Current assignee: Cheng Zexiang; Sansui Optical Technology Suzhou Co ltd
Priority date: 2014-11-11
Filing date: 2015-08-31
Publication date: 2020-07-07
Anticipated expiration: 2035-08-31
Also published as: WO2016076000A1; CN106062600A

Abstract

The present invention relates to a combiner which is used for a mobile phone and a vehicle-mounted laser projector, has high environmental tolerance and high light efficiency, can be mass-produced at low cost, and is a miniaturized combiner for combining red, green, blue and near-infrared multi-wavelength light beams, and a light source using the combiner. In the hollow light guide of the first aspect or the bundle-shaped optical fiber of the fourth aspect having a fine cladding diameter of Φ 10 μm or less, the multiplexer is not affected by the longitudinal mode and the transverse mode of the light beam having a wavelength and a wavelength bandwidth, and can solve the above-mentioned problems such as the improvement of the environmental resistance, the light efficiency, and the productivity, and further, when the multiplexer is used together with the chip LD for surface mounting, it is possible to mass-produce at low cost the optical fiber output type of the third aspect, the thin chip type by LD planar mounting of the fifth aspect, and the multi-wavelength small laser light source of various practical levels having a cylindrical or rectangular outer shape by LD three-dimensional mounting of the sixth aspect.

Description

Light beam combiner and chip type multi-wavelength laser light source

Technical Field

The present invention relates to a light source technology of three primary colors RGB (R, G, and B) used for medical diagnosis and treatment using light, optical communication, MEMS or DMD based scanning type or LCOS based projection type projectors, such as image processing devices, endoscopes, and ophthalmic devices.

Background

In conventional optical communications, an Arrayed Waveguide Grating (AWG) is often used in a multiplexer based on optical fiber wavelength division multiplexing (patent document 1). Recently, in order to use a projector type compact laser display for mobile phones and vehicle-mounted applications, a compact waveguide type RGB three-wavelength multiplexer has also appeared (patent document 2). Further, there are an optical fiber output and a filter type RGB combiner which are low in cost and high in coupling efficiency (patent document 3).

Documents of the prior art

Patent document 1: japanese patent laid-open No. 2005-234245

Patent document 2: japanese patent laid-open publication No. 2013-195603

Patent document 3: japanese patent laid-open No. 2013-228651

Disclosure of Invention

Technical problem to be solved by the invention

Although various multi-wavelength combiners can be produced according to the above-described conventional techniques, in applications other than optical communications, for example, in apparatuses and devices such as projection type projectors using laser light, the following conditions and limitations are imposed on the operation of these conventional combiners in terms of general evaluation criteria, such as optical loss, wavelength band, transverse mode of light beam, productivity, and cost.

Conventionally, optical loss is not negligible including optical coupling efficiency from a light source to a combiner, loss of a combining optical system inside the combiner, and optical transmission loss inside the combiner, and such optical loss increases as the number of combined wavelengths and the number of light sources increase.

In addition, the conventional wave-combining technology depends greatly on the transverse modes of incident and outgoing light beams, regardless of whether the light source is an LD or an LED, and regardless of whether the component on the wave-combiner side is an optical fiber or a waveguide.

In addition, in the conventional multiplexer, the wavelength of each light to be multiplexed is multiplexed based on the wavelength difference, and a transmission or reflection type filter or a diffraction element based on the wavelength is used. On the other hand, when a waveguide-type or optical fiber-type multiplexer is used, the confinement of light in the waveguide or optical fiber is performed by the refractive index difference between the core and the cladding material, and thus, it is also related to the transverse mode of the confined light. Because of their wavelength dependence, a light source of 200nm or more and within 1600nm for a sensor is applied to the blue-green-red wavelength of the three primary colors used for projection television display, and the bandwidth of a light source such as an LD is extended to 1200nm, which has not been able to be handled by conventional optical fiber or waveguide technologies at all. That is, most of the existing combiners have wavelength dependence and beam transverse mode dependence.

In summary, the existing problems of the optical loss of the combiner, and the limitations and dependencies on the transverse mode, wavelength and wavelength bandwidth of the light beam are the main technical problems to be solved by the present invention.

There is a demand for mass production of projection televisions, particularly for vehicle-mounted and mobile phone applications, and there is a need for a production method of a multiplexer that can satisfy the above requirements, such as productivity and product reliability due to the semiconductor process technology, low cost and high performance, and a very small product such as a chip type.

Technical scheme for solving technical problem

One of the main technical problems to be solved by the present invention is the wavelength dependence of the light combined by the existing combiner and the transverse mode dependence of the combined light beam. First, as a method for solving these problems, a hollow light guide having no wavelength dependence in the multiplexer according to the first aspect of the present invention can be used as a medium for transmitting light. As another method for solving these problems, a reflective film made of metal or the like that is hardly dependent on the wavelength is attached to the inner wall surface of the light guide in the first mode, thereby confining the light beam in the light guide regardless of the wavelength of the incident light. In addition, the light beam transmitted through the light guide can be confined in the light guide by reflection of the film attached to the side surface of the light guide regardless of the transverse mode, that is, regardless of the beam diameter and the beam divergence angle, and thus the dependence of the combiner on the beam transverse mode can be solved by the above-described methods.

In the combiner according to the fourth aspect, as a method for solving the above problems, a bundle-shaped optical fiber is used, and the type of each bare optical fiber to be bundled is individually selected from the wavelength characteristics and the beam transverse mode characteristics of each incident light source, so that the combiner is not affected by the wavelength and the bandwidth of the light source to be combined and the transverse mode of the beam.

Therefore, the combiner manufactured by using the hollow light guide according to the second aspect and the constituent element of the bundle-shaped optical fiber according to the fourth aspect as the technical means can be applied to an LD of a single transverse mode, an LED containing a very high order mode, or other surface light sources, and has little dependence on wavelength from ultraviolet to near infrared, or on wavelength bandwidth.

Further, the problems of the total light efficiency of the combiner include, specifically, improvement of coupling efficiency of incident light beams in the combiner, improvement of combining efficiency of an optical system used when a plurality of light beams incident into the combiner are coupled into one light beam, and overcoming of transmission loss and emission end loss of light in the combiner. In the multiplexer according to the first aspect, a hollow light guide is used as a method of improving light efficiency. First, since the hollow light guide is hollow, there is no light absorption, and since a thin film having a high reflectance is attached to the inner wall of the hollow light guide, light can be sealed well, and transmission loss is small. And the shape of the incident end of the light guide can be designed according to the characteristics of the incident light beam, so that the coupling efficiency of the incident light is improved. In addition, in the bundle-shaped optical fiber combiner according to the fourth aspect, since the optical fibers are individually selected according to the wavelength and the beam characteristic of each incident light source, the maximum coupling efficiency can be obtained by the method with the coupling method most suitable for each incident light. Further, since the light coupled to each optical fiber is directly coupled to the output end and output, there is almost no loss in the multiplexer main body except for the loss at the time of coupling the incident light at the input end.

In order to solve the problem of mass production with high reliability, miniaturization, and low cost, a method for manufacturing a hollow light guide of a multiplexer according to a first aspect of the present invention, that is, a method for manufacturing a multiplexer by bonding a substrate having a groove with a reflective film and a cover plate with a reflective film, can solve the problem. That is, if the substrate according to the second aspect is made of a general material such as silicon or glass, the light guide groove according to the second aspect can be easily formed with high accuracy by using an etching device for semiconductor processes or a laser beam direct forming device. Further, the metal or dielectric thin film can be coated on both side surfaces and the bottom surface of the groove for light guide engraved on the substrate according to the second aspect by plating, or evaporation methods such as PVD (Physical Vapor Deposition) and CVD (Chemical Vapor Deposition). The above-described manufacturing method enables mass production at low cost, as in the manufacture of semiconductor components. The combiner according to the fourth aspect is fabricated by a bundle fiber, and is a method capable of mass production at low cost. Further, the multiwavelength light source according to any of the fifth and sixth aspects of the present invention can be mass-produced at low cost and with high reliability, regardless of whether it is managed or produced, because the combiner which is low in cost, highly reliable, and mass-producible according to the first and fourth aspects can be used as a component, and can be prepared in advance independently of the original N light sources.

Effects of the invention

In the first mode, since a hollow light guide having no wavelength dependence is used, the multiplexing of multiple wavelengths of light can be performed in a wide bandwidth of 1000nm or more from ultraviolet to visible and near infrared. The combiner according to the fourth aspect is applicable to a transmission band of bare optical fiber glass over a wide bandwidth from ultraviolet to near infrared because a bundle-shaped optical fiber is used. That is, the two types of wave combiners according to the first and fourth aspects of the present invention are almost independent of wavelength and wavelength bandwidth, and have excellent effects in wavelength characteristics.

In addition, since the hollow light guide according to the first aspect can block light almost regardless of the divergence angle of the input light beam by the reflection film attached to each side surface with respect to the light transmission direction, the LED of the high-order multiple transverse modes from the single transverse mode LD to the surface light source can combine light sources of each wavelength and each transverse mode according to the application almost without depending on the beam transverse mode. In the bundle-shaped optical fiber according to the fourth aspect, the type of the bare optical fiber can be selected according to the characteristics of the transverse modes of the incident light source beam. That is, the two types of wave combiners according to the first and fourth aspects of the present invention have excellent applicability to the transverse mode of the incident light source beam.

In view of the basic structure, in both the light guide according to the first aspect and the bundle-like optical fiber according to the fourth aspect, the incident light is directly coupled from the light receiving end face to the light emitting end and emitted from the light emitting end for each light source for combining, and therefore, there is almost no loss, and the efficiency of the combiner main body approaches 100%. Especially, when the light source is a single transverse mode LD, the total light efficiency from the light exit to the output of the combiner can reach 70% when the combiner of the first mode is used, and can reach more than 90% when the combiner of the fourth mode is used, and the efficiency improvement effect is very significant. In addition, since the two types of wave combiners are made compact, the transmission path of light inside the wave combiner is directly connected between the incident end and the exit end and has a very short distance as described above, and thus spatial coherence of light beams can be maintained to the maximum extent during transmission.

The two types of multiplexers according to the first and fourth aspects are essential key components of a multi-wavelength light source manufactured from the above multi-wavelength multi-surface mount LD light source, and have an effect of improving product reliability and practicality because they are compact and thin chip types.

Since the semiconductor manufacturing method such as etching of the hollow light guide groove and vapor deposition of the reflective film described in the second aspect is used, the multiplexer described in the first aspect can be mass-produced at low cost. Further, the chip-type multiplexer using the bundle optical fiber according to the fourth aspect can significantly reduce the cost as compared to the conventional waveguide-type or filter-type multiplexer. The first and fourth embodiments of the present invention provide two types of wave combiners as key components of a multiwavelength light source, which are also effective in mass productivity and cost.

Further, according to the third aspect, a multi-wavelength light source for optical fiber output can be realized by a compact thin-chip combiner. In the case of the glasses-type and vehicle-mounted head-up display type projectors, since the light source transmits light through an optical fiber, the light source and the display device can be separately provided. For example, in a glasses type projector, a light source and a driving power source are placed in a pocket, light is connected through an optical fiber, and only a projector optical system is placed on glasses, so that it is possible to achieve weight reduction and size reduction. In the case of vehicle-mounted use, since the temperature change in the vehicle interior is large as the placement position of the head-up display projector, the operation condition of the device needs to satisfy a temperature range of minus 30 ℃ to minus plus 90 ℃, and it is very difficult to operate the LD light source in such a large temperature range, and by using an optical fiber multiplexer, the RGB three-wavelength LD and a driver are placed in another place where temperature management is easy, and only the optical system is placed in the head-up display projector that transmits light through the optical fiber, and it is possible to withstand an extremely cold or hot environment. When the multiplexer according to the present invention is used in the above-described application fields, it is possible to provide great convenience in manufacturing various devices. Further, the surface mount LD chip according to the sixth aspect is three-dimensionally mounted to improve heat dissipation, and is formed into a cylindrical shape of approximately Φ 3mm to Φ 6mm or a cubic rod shape of 3mm to 5mm, and has mountability and can be miniaturized as a multiwavelength laser light source used for Wearable (Wearable) electronic devices.

Drawings

Fig. 1 is a conceptual diagram of a first embodiment of a multiplexer structure using N incident and 1 outgoing hollow light guides, manufactured according to a method described in the second embodiment. The upper layer is a cover plate with a light reflection film attached to the lower surface, the lower layer is a substrate engraved with N +1 grooves for light guide, and the side surfaces and the bottom surface of the grooves are covered with light reflection films. By bonding the two, N incident and 1 outgoing light guides, i.e., N +1 light guides, are formed. The light beams of the respective wavelengths input into the incident light guide are closed before reaching the output end of the exit light guide by the total reflection film of light additionally coated on the lower surface of the cover plate and the respective side surfaces and bottom surfaces of the N +1 grooves for light guide.

Fig. 2 is a diagram showing a cross-sectional structure of a light guide of a combiner manufactured by grooving a substrate, that is, a pattern for forming an incident light guide and an exit light guide on the substrate, according to a second embodiment of example 1. In fig. 2, the image is enlarged for clarity of the structure of the grooves and the coupling portions for the light guides, but is not drawn to scale. In the single transverse mode LD, the incident and exit light guides of the combiner formed from the substrate and the external dimensions thereof will be described in detail in example 1 below.

Fig. 3 is a spatial combiner of 3 pairs of 1 beams in which 3 beams are input and 1 beam is output in embodiment 2 using a bundle-shaped optical fiber having N-3 in the fourth formula.

Fig. 4 is a photomicrograph of the exit end face of 3 optical fibers bundled in a bore of 25 μm inner diameter at the center of a ferrule attached to the output end of the combiner of fig. 3, the 3 optical fibers having a cladding diameter of Φ 10 μ.

Fig. 5 shows a compact thin chip type RGB laser light source in example 2, in which 3 pairs of 1 s shown in fig. 3 are used as the multiplexer, and light sources on the input side of the multiplexer are RGB three-wavelength single transverse mode surface mount type LDs of 638nm, 520nm, and 450 nm.

Fig. 6 is a three-dimensional CAD design drawing showing the configuration of an RGB light source of a cylindrical shape as an example of embodiment 3. In the figure, three surface mount LDs are three-dimensionally mounted in a circle-symmetric manner, and the bundle-shaped optical fiber type 3-to-1 combiner described in the fourth embodiment is used.

Fig. 7 is a three-dimensional CAD design drawing showing a structure of a multiwavelength light source for three-dimensionally mounting an LD, which is another example of embodiment 3. The right part of the drawing shows four wavelength light sources of RGB and NIR having a square-bar shape in outer shape, four surface mount LDs are installed on the faces around the cube in a centrosymmetric manner, and the 4-to-1 combiner uses the beam-shaped optical fiber combiner described in the fourth embodiment. In addition, the square rod-shaped light source (light source assembled by the parts 711-732 in the figure) on the right side in the figure is placed in a cylindrical metal shell (740 in the figure) which is positioned on the left side in the figure and has the functions of heat dissipation and protection, and the external shape can be changed into a cylinder.

FIG. 8 is a photograph of the outer shape of the test articles of examples 3 and 4. The left photograph 801 is a cylindrical RGB three-wavelength LD light source described in example 3, and the right photograph 802 is an RGB three-wavelength light source using a fiber output type multiplexer as an example 4 in the light guide described in the third embodiment.

Detailed Description

Example 1

Fig. 1 schematically shows a structure of a multiplexer using a hollow light guide according to a first embodiment manufactured by a method according to a second embodiment of the present invention. The detailed shapes and dimensions of the input and output light guides and the coupling portions shown in the figures vary depending on the difference in the transverse modes of the input light source and the associated output side light beam. In addition, the dimensions of the light guide in fig. 1 are not shown to scale with the substrate dimensions, but are shown arbitrarily enlarged for clarity of the basic parts of the respective configurations.

First, a method of forming a hollow light guide according to a second aspect of the present invention is shown in fig. 2 by using a 3-to-1 three-wavelength multiplexer for a single transverse mode LD having a wavelength RGB (red, green, and blue). In the method of manufacturing light guides by grooving the substrate described in the second mode, 4 grooves in total of 3 input sides and 1 output side on the substrate of fig. 2 form the hollow portions of the light transmission medium of these hollow type light guides. That is, the shape of each groove on the substrate shown in fig. 2 is the shape of the actual light guide itself, and is also the formation pattern of the light guide of the multiplexer. Since the light source in this example is an RGB single transverse mode LD, the cross section of each light guide of the multiplexer, that is, the cross sectional shape of the groove on the substrate is an extremely fine square of about several micrometers (μm) designed in accordance with practical levels. The dimensions of the grooves in fig. 2 are not shown to scale with the substrate dimensions, but are arbitrarily enlarged to show the detailed shape of these light guides.

The light source in this embodiment 1 has three wavelengths of red 660nm, green 520nm, and blue 450nm, and is a high-brightness single-transverse-mode LD. Typical beam characteristics are a spot width on the fast axis fa (fast axis) of 25 ° divergence angle FAHM (full angle Half maximum), about 1.5 μ M, a spot width on the slow axis sa (slow axis) of 10 ° FAHM, about 5 μ M, and a beam quality factor M Λ 2 of about 1.2.

According to the first aspect of the present invention, in this example, N is 3, the number of light guides is 4 in total, i.e., 3 incident lights N and 1 outgoing light, and 1 outgoing light is merged with 1 of the 3 incident lights having a red wavelength, so that fig. 2 appears to have only 3 light guides of three RGB wavelengths.

First, when light is directly coupled between the LD and the light guide without using a lens, the cross-sectional shapes perpendicular to the light transmission direction of the light guide shown in fig. 2 were all 6.5 ± 0.5 μm in the lateral direction (width direction of the groove in fig. 2) and 3.5 ± 0.5 μm in the longitudinal direction (depth direction of the groove), and test pieces were produced based on these values. At this time, the light efficiency of the combiner was examined using 3 single transverse mode LDs of three colors of RGB. By first placing the LDs FA and SA in the longitudinal and transverse directions of the combiner of this example, and then aligning the light emitting points of the LDs with the center positions of the light receiving surfaces of the light guides on the input side of the combiner of this example in both the longitudinal and transverse directions, and aligning the light emitting points with the light receiving surfaces at a distance of about 5 μm in the optical axis direction, the total efficiency of light can be obtained at a ratio of 75% red, 71% green, and 68% blue from the exit of the output side of the combiner of this example, compared to the original output of the LDs. The outgoing light beam emitted by the wave combiner has a value of M & lt2 & gt ═ 1.6 or so, which is much better than the expected value of M & lt2 & gt, 2.1. This result can be obtained because the combiner in this example is a small-sized combiner, and the optical path length of the light guide is only about several mm from the entrance to the exit, and the light beam does not completely diffuse to the desired higher-order transverse mode.

When a light beam is shaped into a substantially square shape and coupled to a combiner by using a cylindrical lens having a magnification of 1 to 2.5 in the FA direction and a magnification of 1 to 1 in the SA direction between the LD and the light guides, the cross-sectional shape of each of the RGB light guides is also adjusted to a square shape of 5 μm in both the lateral direction and the longitudinal direction at the incident side of the combiner in accordance with the shape of the incident light beam. The output of the RGB light source using the combiner is a single transverse mode light beam with M & lt2 & gt & lt1.3, and the comprehensive light efficiency of about 90% is obtained.

In this example 1, a process was used in which a photoresist was applied to the upper surface of a silicon wafer substrate having a thickness of about 1mm or less, a trench having a cross-sectional shape as described above was formed by dry etching, and then a gold thin film was deposited on the side and bottom surfaces of the trench, fig. 2 is not in proportion to the actual size, and in the multiplexer of this example, 3 light guides arranged laterally on the incident side were mounted with a space of 1.5mm and a length direction of 5mm to form a chip having a width W5mm × and a length L5mm × and a thickness of about t1.5mm, and the multiplexer was mounted in cooperation with a surface-mounted RGB three-wavelength LD to try to produce a light source which is a single transverse mode output of three primary colors of RGB and has an external shape of W5mm × L8mm × t2.5mm when directly coupled, and an external shape of W5mm × L12mm × t2.8mm when coupled by a lens, both of which are compact chip types.

Example 2

A multiplexer according to a fourth aspect of the present invention, which is applied to a chip type using a bundled optical fiber and to an RGB three-wavelength single transverse mode LD with N ═ 3, is shown in the CAD drawing of fig. 3 as example 2. The subject matter of embodiment 2 is a chip-type light source of RGB three primary colors LD according to a fifth aspect of the present invention using the multiplexer, and the basic structure of the light source is shown in fig. 5.

If the bare optical fibers bundled by the combiner have a single transverse mode, that is, NA is 0.12 to 0.13 and core diameter Φ is 3.5 to 4.0 μm, the transverse mode of the primary light source LD is matched, and spatial coherence of the light beams output from the combiner is not disturbed. However, the commercially available single transverse mode optical fiber is not suitable for use in embodiment 2 because its cladding diameter is Φ 125 μm. The ideal bare optical fiber is a bare optical fiber with a core diameter of phi 4 μm and a cladding diameter of phi 6-8 μm, but the present invention is applied to make a combiner using an existing product of the bare optical fiber with NA of 0.2, a core diameter of phi 7 μm, and a cladding diameter of phi 10 μm according to the practical level. Single transverse mode bare fiber with cladding diameter less than 10 μm is still under development, and low melting point inorganic glass or plastic material is used.

Fig. 4 is a photomicrograph showing the emission end surfaces of 3 optical fibers bundled on the output side of the RGB three-wavelength single-transverse-mode combiner of example 2 configured in fig. 3. The distance between adjacent cores of 3 fibers bundled closely together in a delta shape of an equilateral triangle is about 10 μm. In the manufacturing method shown in the photograph of FIG. 4, since the end faces of the bundled 3 optical fibers were polished, 3 bare wires were inserted into a glass tube-shaped ferrule having a center with a small hole of about 25 μm and an outer diameter of 1mm, and fixed with an adhesive. On the input side of the combiner, the incident end faces of 3 optical fibers were arranged laterally at intervals of 2mm from each other. The RGB multiplexer described in the fourth embodiment, which has N ═ 3, is a chip-type multiplexer having a width and a length of 6mm and a thickness of about 2 mm.

At present, when the light coupling is directly performed between the LD and the optical fiber without a lens using the RGB three-wavelength chip-type light source using the above-mentioned bundle-type optical fiber combiner having NA0.2, core diameter Φ 7 μm bare wire, and N ═ 3, as shown in fig. 5, the external form thereof is 6mm wide, 8.5mm long, and 1.8mm thick, and the maximum optical coupling efficiency between the LD and the optical fiber of the combiner can be about 65%; when a coupling lens is used between the light source LD and the combiner, the coupling efficiency of light can be increased up to 85%, but the longitudinal direction of the outer shape thereof reaches 11 mm. At present, two end faces of the beam-shaped optical fiber for incidence and emergence are not attached with anti-reflection dielectric films, and if the anti-reflection dielectric films are attached, the light coupling efficiency can be further improved by more than 5%. Basically, the combiner in fig. 5 can be switched from the bundle fiber system described in the fourth embodiment to the hollow light guide system described in the first embodiment. The characteristics of both are almost the same as described above, and the manufactured RGB light source can also perform single transverse mode output with the same chip-type profile and the same level of coupling efficiency. That is, the RGB light source according to the fifth aspect of the present invention shown in fig. 5, which is the subject matter of embodiment 2, covers the chip-type multiplexer according to the first and fourth aspects.

In example 2, the transverse mode characteristics of the RGB three-wavelength light beams emitted from the bundle fiber to the output side of the combiner were also examined. Trial calculation is carried out according to the diameter of the bare optical fiber inner core of 7 mu M and the NA of 0.2, and the numerical values of the quality factor M & ltlambada & gt 2 relevant to the transverse mode of the light beam are respectively as follows: the red wavelength was 3.5 at 638nm, the green wavelength was 4.2 at 520nm, and the blue wavelength was 4.9 at 450nm, and the measured values were all 2 or less in red, green, and blue, which are almost close to a single transverse mode. The reason for this is that the length of the bare optical fiber of the combiner in this example is about 6mm, the transmission distance of the light beam in the optical fiber is extremely short, the effect of mixing the higher-order mode is not yet prominent, and the transverse mode of the input light beam reaches the output end without being disturbed.

Further, the coaxiality of the RGB three-wavelength light beams emitted from the light source in example 2 was examined, and a colorless (achromatic) lens having a focal length of 20mm was placed at the exit of the bundle-shaped optical fiber, and the beam diameter at 1m front was calibrated to be the minimum, and the beam spot diameters (FWHM) of the three beams of R, G, and B, which were finally measured, were about Φ 0.5mm or less. Further, the three light beams having three wavelengths are spaced apart from each other by about 0.5mm within a concentric circle of Φ 1.5mm, and therefore, from the practical level, they can be used as one light beam having three wavelengths.

From the above evaluation results, the outputs after using the combiner of example 2 were 135mW for 160mW output at 638nm red, 65mW output at 520nm green, and 62mW output at 450nm blue, respectively, as compared with the output light from the original LD, and the three-wavelength light beams emitted from the combiner fiber were almost all in the single transverse mode, and thus the requirements of high luminance and high output to be provided as projection type projectors for vehicles and mobile phones were satisfied.

Example 3

Since the RGB multiwavelength light sources of

embodiments

1 and 2 described above are mounted in parallel with a plurality of LDs on the same plane capable of dissipating heat, even a plurality of surface-mounted LD chips with high output of 100mW or more per wavelength would have a significant problem of heat dissipation due to high current consumption and high-density mounting with extremely small size. The RGB light source of the present embodiment 3 is different from the above 2 embodiments in that a plurality of LD chips are mounted on one plane, and a surface mount type LD chip is used, but three-dimensionally mounted by the method described in the sixth embodiment, and the external shape thereof is a cylindrical or polygonal rod-shaped three-dimensional shape. In the light source of this example, the plurality of LDs are three-dimensionally mounted in this manner, so that not only is the heat dissipation improved, but also the light source can be formed into a shape that is easy to mount for various applications by changing the outer shape to a cylindrical shape or the like.

As an example, the assembly principle and the structure of the RGB light source are shown in fig. 6, in which three of the surface mount chip LD, the coupling lens, and the beam-shaped optical fiber combiner according to the fourth aspect are three-dimensionally mounted by the method according to the sixth aspect. Since the light source has a cylindrical shape, three light emitting points from the RGB LD which are three-dimensionally assembled inside a cylindrical metal case and three light receiving end surfaces from the 3 optical fibers which are positioned on the incident side of the combiner are aligned with each other in a manner of 1 to 1 of the light emitting points and the light receiving surfaces, and distributed in an equilateral triangle delta of the same size, and the light output from each of the three LDs is coupled to each of the 3 optical fibers by passing through each of the three optical fiber end surfaces using three coupling lenses. In this FIG. 6, a cylindrical shape with a length of 8mm and a diameter of 5.6mm was designed and trial-produced. If the optical fiber is directly coupled without using a lens, the size can be reduced to 4.8mm in diameter and 6mm in length.

Fig. 7 is an assembly configuration diagram of an assembly of visible RGB and near-infrared four-wavelength LD light source modules mounted in a square shape as another example. As in the example of fig. 6, 4 coupling lenses are used to couple 4-wavelength light beams emitted from four LDs in a three-dimensional distribution to a combiner of 4-to-1-bundle optical fibers in the same three-dimensional distribution. The square 4-color LD module (711-732 set in the figure) on the right side of FIG. 7 can be packaged in a cylindrical housing case (740 in the figure) with an outer diameter of phi 5mm and a length of 8mm on the left side. The left photograph in fig. 8 shows one of the prototype products of the RGB-NIR light source packaged in the past. The module has the size of 6mm outside diameter and 12mm length.

Example 4

Embodiment 4 is an RGB light source using a fiber-optic type combiner in a light guide as described in the third embodiment, as shown in the right photograph of fig. 8. Laser emitted by the pot-shaped single transverse mode RGB LD with phi 3.8 is coupled into the input side light guide of the wave combiner by using a lens, in addition, output light of the output light guide is also coupled onto 1 single transverse mode optical fiber by using the lens, and finally, the output of the optical fiber is about 60 percent of the output of the original LD.

The key point of the application device of the multi-wavelength LD light source using the combiner according to the embodiment 4 is the optical fiber output. The light transmission is performed between the light source including the LD and the output end of the optical fiber through the optical fiber, so that a desired light can be output to an application device at a place spaced apart from the light source, and the heat dissipation problem can be easily solved by separately placing only the light source main body alone. In the case of the above-described vehicle-mounted projector, even when the ambient temperature of the installation place of the head-up display type projector for outputting light is in a wide range of minus 35 ℃ to minus 90 ℃ or more, the RGB light source main body including the LD is placed alone, and thus the normal operation is possible. That is, such a light source is indispensable for the application in the vehicle.

Industrial applicability of the invention

If the chip combiner of the first and fourth aspects is used as a key component and the mounting technique of the fifth aspect is applied, a flat-surface-mount, thin and compact, multi-wavelength light source can be manufactured, and the chip combiner can be applied to a mobile phone or other wearable display device requiring miniaturization, for example, a laser projector using MEMS, DMD, LCOS, or the like.

Further, in the multiwavelength light source using the optical fiber output type multiplexer according to the fourth aspect, since transmission is performed between the LD light source and the destination "projector" of light via the optical fiber, it is more easily endurable in severe temperature environments such as in-vehicle and field, and thus it is applicable to applications such as in-vehicle fields.

In addition, in the sixth aspect, since the multi-wavelength and high-output LDs are three-dimensionally mounted together, and a cylindrical multi-wavelength light source having an outer diameter of Φ 5mm or less can be manufactured, the multi-wavelength light source can be used in a wearable laser display device such as a laser pen or a glasses type, because the multi-wavelength light source can be easily mounted in an external shape and the heat dissipation can be improved.

Further, in regard to the mounting of the small multi-wavelength laser light source, if various component parts of the combiner described in the first and fourth aspects are used, the mounting can be divided into two major operations, that is, the mounting operation of the combiner itself by the mounting of each internal component and the mounting operation of coupling the light emitted from each individual LD to the combiner.

Description of the reference symbols

Relevant reference numbers of fig. 1:

110 substrate of multiplexer of first mode, on which light guide grooves are engraved

111 an upper surface of the substrate 110, the upper surface having grooves for light guide engraved thereon

112, N +1 grooves for light guide engraved on the surface 111, where N-1, …, and N denote the nth incident light guide and N-N +1 denotes the 1 outgoing light guide

113 incident and exiting light guide grooves, and metal thin films or dielectric thin films coated on the side surfaces and bottom surfaces thereof for totally reflecting light in order to block the light

120 and a cover plate attached to the upper surface of the substrate 110 for covering the light guide grooves

The lower surface of the cover plate 120 121, that is, the surface where the light guide grooves engraved on the upper surface 111 of the counter substrate 110 bonded to the surface are covered to form a light guide. In order to enclose the light in the formed light guide, the surface is coated with a metal or dielectric film that totally reflects the light

FIG. 2 associated reference numbers:

200 output end of groove for outgoing light guide of combiner of first mode manufactured by method of second mode

Input end of 1 st red wavelength incident light guide of 3 (201N) ═ 3

202 light beam input end of 2 nd blue wavelength incident light guide

203 beam input end of 3 rd green wavelength incident light guide

210 groove for exit light guide

211 st 1 st red wavelength light guide groove

212 groove for 2 nd blue wavelength incident light guide

213 groove for incident light guide of 3 rd green wavelength

222 incident and outgoing light guide coupling for 2 nd blue wavelength

The coupling of the 223 rd 3 green wavelength entrance and exit lightguides is in color

As shown in fig. 2, the 1 st red wavelength is a straight line from the input end 201 to the output end 200, that is, the input light guide 211 is directly connected to the output light guide 210 without a coupling portion, and the number of the two is 1.

FIG. 3 associated reference numbers:

300 fourth mode of chip template with optical fiber fixed in bundled optical fiber type wave combiner

301 input side of a multiplexer

Output side of 302 wave combiner

310 micro-grooves at the outgoing end of the chip-type thin plate of N3 fibers tightly bundled at the output side of the combiner (the end surface of the micro-grooves at the outgoing end is triangular and has a V-shaped groove shape as shown in the figure)

31i i ═ 1, 2, 3; micro-groove at the incident end of the chip-type thin plate of each of the 3 optical fibers at the input side of the combiner (as shown in the figure, the end surface of the micro-groove at the emergent end is triangular and is in the shape of a V-shaped groove)

32j j ═ 1, 2, 3; 3 grooves on the chip template 300 for high-precision positioning and fixing of 3 optical fibers

Fig. 4 (photomicrograph) relevant reference numerals:

400 emission end face of ferrule bundled with optical fibers at output side of wave combiner shown in FIG. 3 after polishing

41i i is 1, 2, 3; the bare wires of 3 optical fibers with the cladding diameter of phi 10 mu m bundled on the end face of the ferrule are tightly bundled together in an equilateral triangle delta shape as can be seen from the photograph

Inner core of 421 optical fiber bare wire

Cladding of 422 optical fiber bare wire

430 micrograph, unit length 10 μm

FIG. 5 associated reference numbers:

501 Blue (Blue)450nm wavelength surface mounting COS type single transverse mode LD

502 Red (Red)638nm wavelength COS type single transverse mode LD

503 Green (Green)520nm wavelength COS type single transverse mode LD

504 RGB three-wavelength LD heat dissipation copper plate

505 the first embodiment of the present invention is a chip-type optical fiber-fixed multiplexer, which is composed of the board 505 and 3 bundled optical fibers 51i (i: B, R, G three colors)

In fig. 51i, three colors i-B, R, G are respectively arranged from the left, the input end of the combiner is 3 optical fibers N which are installed in a 1-to-1 direct optical coupling manner with an RGB LD light source, and in this embodiment 1, the sizes of the bare wires of the 3 optical fibers are core diameters Φ 7 μm and NA0.2, and the cladding diameter Φ 10 μm

The output side of 514 wave-combiner satisfies the condition of first mode and the output end face of bundled N-3 optical fibers

FIG. 6 associated reference numbers:

611-i three color i-R, G, B surface mounting type COS type LD (3)

612-j three-color j-R, G, B LD electrodes (3 sets of cathode and anode, total 6)

613-k three-color k-R, G, B radiator for LD heat radiation (3 sets)

621-s coupling lens (3 sets) for optically coupling from LD of three colors(s) R, G, B to combiner

630 combiner body consisting of 3 bundled optical fibers 631-i (i ═ R, G, B)

631-t three bundled optical fibers of a combiner for receiving light from an LD having three colors t-R, G, B

The RGB three-color LD light source main body is composed of the right-hand components in the figure, such as the above-mentioned 611-i LD, 612-j LD electrode, 613-k heat sink, 621-s coupling lens, and 630 wave combiner, and is three-dimensionally mounted in the arrangement relationship in the figure to form one module.

Light beam exit port of 632 bundle optical fiber type wave combiner

640 for accommodating the three-color RGB laser light source main body module on the right side of the figure, and has a cylindrical shape with a dimension of L8mm × Φ 5.6mm

Relevant reference numbers of fig. 7:

711-i four-color i-R, G, B, NIR near infrared surface mount COS type LD (4)

712a-j four-color j R, G, B, NIR + electrode of LD (4 anodes in total)

712b-j four colors j R, G, B, NIR of LD-electrode (4 cathodes in total)

713 Heat sink for Heat dissipation with four LDs of RGB and NIR bonded together

721-k four sets of coupling lenses coupled from four color k-R, G, B, NIR LDs to a combiner

730-beam optical fiber type 4-to-1 combiner body

731-s four bundle optical fibers of combiner for receiving light from four-color s-R, G, B, NIR LD

732 beam exit port of bundled optical fiber combiner of fourth embodiment

The RGB + NIR four-color LD light source main body is composed of the right-hand components in the drawings, such as the above-mentioned 711-i LD, 712a-j and 712b-j LD electrodes, 713 heat sink, 721-k coupling lens, 730 combiner, and the like, and is three-dimensionally mounted in the arrangement relationship in the drawings to form one module.

740 an outer case for accommodating a 4-color LD light source main body of RGB + NIR on the right side in the figure, the outer case being cylindrical in shape and having a size L8mm × Φ 5mm

Fig. 8 (photo) related reference numerals:

801 photograph of a prototype of a cylindrical RGB three-wavelength light source module having a LD stereoscopically mounted thereon according to example 3 of the sixth embodiment

802 photograph of fiber output RGB three-wavelength light source module using light guide type wave combiner of embodiment 4 according to the third mode

810 RGB three-wavelength light source main body mounted with LD, wave combiner and emergent optical fiber

811 green 520nm wavelength, Can-3.8 package, single transverse mode LD

812 red 638nm wavelength, Can-3.8 package, single transverse mode LD

813 blue 450nm wavelength, Can-3.8 package, single transverse mode LD

821 Single transverse mode fiber for coupling light beams emitted from RGB three-wavelength LD and outputting light from light source 810 to outside

822 optical fiber 821 and light of three RGB wavelengths output from the end face of the ferrule

Claims

1. A light beam combiner for spatially combining a plurality of light beams into a light beam from one point light source and outputting the light beam, comprising:

a plurality of bare optical fibers having an outer diameter of 10 μm, each of the bare optical fibers having an incident end surface and an exit end surface for a light beam and including an inner core and a cladding having a thickness of 1 μm or less; and

a chip template, wherein the surface of the chip template is provided with a plurality of fixing grooves for respectively fixing the bare optical fiber,

the fixing groove includes: a plurality of incident portions provided so that the incident end surfaces are arranged at intervals from each other along one edge of the chip-type board; and an emitting portion that is provided with the emitting end surface at the other edge of the chip mold, the fixing grooves being provided on the surface of the chip mold so as to correspond to the bare optical fibers, respectively, so that the bare optical fibers are guided from the incident portion to the emitting portion, respectively,

the plurality of fixing grooves are close to each other as they go from the incident portion toward the exit portion, and the plurality of fixing grooves are combined into one groove at the exit portion,

in the combined fixing groove of the emission part, the bundle of the bare optical fibers, which is bundled in a tight state and fixed with an adhesive, is fixed in the combined fixing groove.

2. The beam combiner of claim 1,

the groove cross-sectional shape of the fixing groove after the merging at the emission portion is a narrowed shape in which the groove width is narrowed toward the groove bottom in the groove depth direction, for fixing the bundle of the plurality of bare optical fibers.

3. A chip-type multi-wavelength laser light source, comprising:

a combiner for the light beams of claim 1 or 2;

a laser diode light source which is arranged at a position corresponding to the position of the incident portion along one edge of the chip-shaped board and emits light of a plurality of wavelengths different from each other; and

a substrate on which the laser diode light source and the chip-shaped board are placed,

the light beam from the laser diode light source is made incident from the incident portion toward the inner core using a lens, or the light beam from the laser diode light source is made incident directly from the incident portion toward the inner core without using a lens.