Waveguide device, application thereof and laser display device with waveguide device

Abstract

The embodiment of the invention discloses a waveguide device and application thereof, and belongs to the technical field of waveguides, the device comprises a substrate layer and a waveguide layer superposed on the substrate layer, and the waveguide layer comprises a lower cladding, a core layer and an upper cladding which are superposed in sequence; wherein the core layer comprises an input section, an output section and arc turning sections located on the input section and the output section, a laser beam enters from the input section and exits from the output section, and the arc turning sections enable the laser beam to turn at a preset angle from the input direction to the output direction. Through plane integration and arc turning design, the occupied area of a silicon wafer is minimized, and miniaturized integration is realized; moreover, the laser beams are transmitted through the arc turning design, the silicon-based integration process is compatible, required elements are reduced, the assembly cost is reduced, and low-cost quantification of products is facilitated.

Description

Technical Field

[0001] This application relates to the field of waveguide technology, and in particular to a waveguide device and its application, as well as a laser display device having the waveguide device. Background Technology

[0002] Laser display technology is widely used in consumer electronics and professional display fields due to its advantages such as high brightness and wide color gamut. Among them, waveguide devices are particularly important in laser display technology.

[0003] Existing multi-beam combining technologies are generally divided into discrete component combining and planar waveguide combining, among which: Discrete element beam combining uses independent optical elements, which are precisely fixed and adjusted through a mechanical structure to merge multiple laser beams into a single output beam in free space; the overall structure is constructed as a three-dimensional optical path device, typically larger than 10 cm². 3 It is difficult to integrate into small devices; at the same time, the assembly is complicated, the assembly cost accounts for 40% of the total cost, and the optical path alignment accuracy is easily affected by vibration, with a deviation of >1μm, which leads to 10% optical loss. Planar waveguide beam combiners utilize flat optical paths fabricated on a chip to efficiently combine multiple optical signals from different lasers into a single, stronger, and brighter beam. Compared to discrete component beam combiners, they offer improvements in miniaturization and assembly costs. However, the traditional linear layout still has potential for improvement in meeting design requirements for miniaturization, low loss, and low crosstalk.

[0004] Therefore, there is an urgent need for a miniaturized, planar integrated, low-loss waveguide device that is compatible with silicon-based processes. Summary of the Invention

[0005] This application provides a waveguide device and its application, as well as a laser display device having the waveguide device, to solve the problem of the relatively large size of the waveguide device in the prior art, and further solve the problems of limited loss reduction and poor stability.

[0006] The technical solution is as follows: On one hand, embodiments of this application provide a waveguide device, including a substrate layer and a waveguide layer superimposed on the substrate layer, the waveguide layer including a lower cladding layer, a core layer and an upper cladding layer superimposed in sequence; The core layer includes an input segment and an output segment, as well as an arc-shaped turning segment located between the input segment and the output segment. The laser beam enters from the input segment and exits from the output segment. The arc-shaped turning segment enables the laser beam to turn at a preset angle from the input to the output direction.

[0007] Preferably, the bending radius of the arc turning segment is 600~1500μm.

[0008] Preferably, the preset angle is 30° to 150°.

[0009] Preferably, the channel width of the input segment is 5~6μm, and the channel width of the output segment is 8~9μm.

[0010] Preferably, the arc turning segment is constructed as a linear gradient structure, which enables the laser beam coupling efficiency to be greater than 90% and the coupling loss to be less than 0.5dB.

[0011] Preferably, the channel width in the linear gradient structure gradually increases from the input segment to the output segment, with the channel width increasing by 0.6~0.7μm for every 100μm.

[0012] Preferably, the input segment and the output segment are each configured with the same number of segments, the spacing between adjacent output segments is 10~30μm, and an isolation strip is provided between adjacent output segments.

[0013] Preferably, the waveguide end face of the waveguide device is coated with an antireflection film; the antireflection film has a reflectivity change of less than 0.1% in an environment of -40℃ to 85℃ and a peel strength greater than 5N / cm.

[0014] Preferably, the antireflective film is an alternating SiO2 / TiO2 film layer.

[0015] Preferably, the core layer uses SiO2 mixed dopant to adjust the refractive index. Through the doping process, the waveguide refractive index difference between the core layer and the upper or lower cladding is controlled to be 0.25~2%, corresponding to a numerical aperture of 0.10~0.29.

[0016] Preferably, the input segment and the output segment have the same or different waveguide refractive index differences, and the numerical aperture of the input segment and the output segment is 0.12~0.15.

[0017] This application also discloses an application of a waveguide device, including: the application of the waveguide device in multi-beam beam combining in laser display, wherein the output segment spacing of the waveguide device is adapted to the packaging spacing of the laser, and beam combining can be achieved without additional optical path adjustment; It also includes the application of the waveguide device in beam shaping, laser equipment, optical communication, medical, and automotive applications.

[0018] Preferably, the application method of the waveguide device includes: The waveguide device is configured with more than one laser; wherein the more than one laser includes at least one group of RGB semiconductor lasers; The more than one laser is directly coupled to the waveguide device; The more than one laser emits a beam of light, causing the beam to propagate along the waveguide device; Laser display is achieved by controlling the speckle suppression and output beam of the waveguide device.

[0019] Preferably, in the more than one laser, the wavelength difference of the lasers of the same color is 0.5~5nm.

[0020] This application also discloses a laser display device, comprising: Waveguide device; At least one set of RGB semiconductor lasers, wherein the RGB semiconductor lasers are directly coupled to the input section of the waveguide device; The speckle suppression module is directly coupled to the output section of the waveguide device, and achieves a speckle contrast of less than 5% through wavelength diversity or polarization multiplexing.

[0021] Compared with the prior art, the technical solution provided in this application can bring the following beneficial effects: By combining planar integration with circular curve design, the silicon wafer footprint is minimized, enabling miniaturized integration. The circular curve design also facilitates laser beam transmission, ensuring compatibility with silicon-based integration processes, reducing the required components, lowering assembly costs, and enabling low-cost mass production of products. Attached Figure Description

[0022] The present invention will be further described below with reference to the accompanying drawings and embodiments: Figure 1 This is a schematic diagram of a waveguide device provided in one embodiment of this application; Figure 2 An exemplary schematic diagram of a core layer structure is shown; Figure 3 This is the "bending radius - bending loss" curve provided in this application; Figure 4 An exemplary schematic diagram of another waveguide device is shown; Among them, 11 is the substrate layer, 12 is the waveguide layer, 121 is the lower cladding layer, 122 is the core layer, and 123 is the upper cladding layer. Detailed Implementation

[0023] To facilitate understanding, the application scenario of this application is first explained. In the field of laser display, multi-beam combining technology based on silicon dioxide waveguides offers significant improvements over discrete component combining in terms of structural miniaturization, reduced loss, and lower cost. With the emergence of laser equipment, optical communication, medical, and automotive fields, industrial development has been achieved from basic communication (optical communication) to core devices (laser equipment) and then to terminal applications (medical and automotive). Addressing the high demands for color gamut and brightness in different scenarios, the linear layout of waveguide structures in traditional planar waveguide combining still cannot meet the requirements in terms of miniaturization, loss, and crosstalk. Therefore, this application provides a waveguide device.

[0024] refer to Figure 1 In this embodiment of the application, the waveguide device includes a substrate layer 11 and a waveguide layer 12 superimposed on the substrate layer 11. The waveguide layer includes a lower cladding layer 121, a core layer 122 and an upper cladding layer 123 superimposed in sequence.

[0025] Among them, such as Figure 2 As shown, the core layer 122 includes an input segment and an output segment, as well as an arc-shaped turning segment located between the input and output segments. The laser beam enters from the input segment and exits from the output segment. The arc-shaped turning segment allows the laser beam to turn at a preset angle from the input to the output direction. Additionally, it should be noted that... Figure 2 LD1, LD2, LD3, LD4, LD5, LD6, LD7, and LD8 refer to the input ports of the laser.

[0026] In one implementation, the preset angle is defined as 90°, meaning that the input and output directions of the laser beam are at a 90° angle. Of course, in other implementations, it can be defined as other angles suitable for its application scenario; the preset angle is generally defined as 30° to 150°.

[0027] Exemplarily, in this embodiment, the substrate layer 11 is a silicon-based substrate, and the waveguide layer 12 is a silicon dioxide waveguide. The silicon dioxide waveguide device is fabricated using photolithography and chemical vapor deposition processes. The specific fabrication method is as follows: (1) Substrate preparation: Selected <100> The crystal-oriented monocrystalline silicon, with an overall size of 10mm×8mm×500μm and a refractive index of 3.42, serves as a support and is pretreated by RCA cleaning; the cleaning solution is NH4OH:H2O2:H2O=1:1:5, the cleaning temperature is 60℃, and the cleaning time is 10min. (2) Lower cladding deposition: PECVD (plasma-enhanced chemical vapor deposition) was used, with SiH4:O2=1:4, where SiH4 was used to provide the silicon source and O2 was used to provide the oxygen source; the process temperature was 300℃, the pressure was 50Pa, and the deposition thickness was 3μm; the size of the lower cladding obtained after deposition was 10mm×8mm×3μm. (3) Core layer photolithography etching: Use photoresist, such as AZ6130; coating thickness 1μm, pre-baking 90℃ / 30s, exposure dose 100mJ / cm², development 60s, use BOE etching solution (HF:NH4F=1:6), etching depth 4μm; (4) Upper cladding deposition: Using the same PECVD process as the lower cladding, a 3μm thick silicon dioxide layer is deposited at 300℃ and 50Pa with a SiH4:O2 ratio of 1:4. The size of the deposited upper cladding is 10mm×8mm×3μm, thus completely covering the 4μm deep core structure.

[0028] In summary, the technical solution provided in this application minimizes the silicon wafer area and achieves miniaturized integration through planar integration and arc-shaped turning design. Moreover, the arc-shaped turning design transmits the laser beam, is compatible with silicon-based integration processes, reduces the required components, lowers assembly costs, and facilitates low-cost product quantification.

[0029] In this embodiment of the application, in order to further reduce bending loss, the bending radius of the above-mentioned arc turning segment is 600~1500μm, so that the waveguide bending loss is less than 0.05dB / turn.

[0030] For example, the bending radius of the arc-shaped turning segment is obtained through optical field simulation optimization. Taking a preset angle of 90° for the arc-shaped turning segment as an example, the optical field simulation optimization specifically includes the following steps: (1) Model construction: Establish a three-dimensional waveguide model and input parameters (silicon substrate n=3.42, SiO2 (silicon dioxide) waveguide n=1.46, core layer size 8μm×4μm, 90° turn); where n refers to the refractive index; (2) Variable settings: test bending radii of 500μm, 600μm, 700μm, 900μm, 1200μm, and 1500μm to simulate electric field distribution and power attenuation; (3) Loss Calculation: Calculate the loss at each test bending radius according to the formula loss = 10lg(Pout / Pin), and plot the "bending radius - bending loss" curve, as shown in the figure. Figure 3 As shown; where Pout refers to the output power of the laser beam and Pin refers to the input power of the laser beam; (4) Optimization and determination: Based on the "bending radius-bending loss" curve, the minimum radius of the bend with a loss of less than 0.05dB / turn is selected as 600μm. Further optimization is carried out to improve the edge smoothness of the SiO2 waveguide to reduce scattering loss. Finally, 600-1500μm is determined as the optimal bending radius range.

[0031] Moreover, experiments have shown that, based on electromagnetic theory, when the bending radius is greater than or equal to 600 μm, the laser beam is constrained by total internal reflection in the SiO2 waveguide layer, and the evanescent wave leakage power is less than 0.7% / turn, corresponding to a bending loss of less than 0.03 dB / turn. When the radius is less than 600 μm, the leakage power is greater than 1.2% / turn, corresponding to a bending loss of greater than 0.05 dB / turn. Therefore, even considering process differences, the bending loss is consistently less than 0.05 dB / turn when the bending radius is 600 μm or greater than or equal to 600 μm.

[0032] In summary, the selection criteria for the bending radius are: (1) low loss: bending loss is less than 0.05 dB / turn when the bending radius is greater than or equal to 600 μm; (2) miniaturization: the area of ​​the silicon wafer (i.e., the final waveguide device) increases by more than 15% when the radius is greater than 1500 μm; (3) processability: a bending radius of 600-1500 μm is suitable for photolithography etching, which can effectively avoid etching breakage. Therefore, in order to balance low bending loss, miniaturization, and process fabrication effectiveness, the bending radius is limited to 600-1500 μm in this application.

[0033] In the embodiments of this application, the channel width of the input segment is 5~6μm, and the channel width of the output segment is 8~9μm.

[0034] For example, regarding the channel width of the input segment, since the laser mode field diameter matched with the waveguide device is 5~8μm, by setting the channel width of the input segment to 5~6μm, the mode field overlap is greater than 95%, thereby achieving extremely high-efficiency transmission of optical energy from the laser to the waveguide device.

[0035] For example, regarding the channel width of the output segment, the channel width of the output segment is set to 8~9μm to adapt to the low transmission loss requirements of silicon dioxide waveguides. The transmission loss corresponding to 8μm is less than 0.1dB / cm.

[0036] In this embodiment, since the channel widths of the input and output segments are different, the arc-shaped turning segment is constructed as a linear gradient structure. This linear gradient structure ensures that the coupling efficiency of the laser beam is greater than 90% and the coupling loss is less than 0.5dB. This linear gradient structure is used to achieve mode field matching.

[0037] It is important to note that, based on the design of a linearly gradient structure, the inner and outer walls have different physical path lengths due to the continuous change in width, resulting in unequal local bending radii on both sides. To establish a unified performance evaluation benchmark, this application defines the bending radius of the entire structure using the curvature of the centerline of the linearly gradient structure.

[0038] In the embodiments of this application, the channel width in the linear gradient structure increases uniformly, with the channel width increasing by 0.6~0.7μm for every 100μm, until the channel width in the linear gradient structure increases linearly from 5~6μm to 8~9μm.

[0039] Furthermore, the length of the linearly gradient structure was determined to be 500 μm through FDTD (finite-difference time-domain) simulation. Specifically, the calculation was performed using a linear gradient law. The gradient formula is: W(x) = Win + (Wout - Win) × (x / L), where W(x) is the width at a distance x from the input segment, Win = 5~6 μm, Wout = 8~9 μm, and L = 500 μm. This effectively avoids the increase in coupling loss caused by abrupt changes in the mode field. If a nonlinear gradient structure is used, the coupling loss will increase by more than 0.08 dB.

[0040] Moreover, the linear gradient structure widens the lateral alignment tolerance from the traditional ±0.5μm to ±1μm through size gradient. In actual operation, a high-precision placement machine (positioning accuracy ±0.3μm) is used in conjunction with a vision alignment system to identify the laser and waveguide edge features, which can effectively ensure that the coupling efficiency is greater than 90% and the coupling loss is less than 0.5dB.

[0041] In this embodiment, refractive index matching can also be performed by adjusting the refractive index through mixing dopants in the core layer. Specifically, the core layer uses high-purity SiO2 (basic refractive index 1.46), and the refractive index is finely adjusted by doping with 1~2% GeO2, so that the deviation between the refractive index of the core layer and the equivalent refractive index (1.45~1.47) of the laser output light is less than 0.01, reducing the reflection loss caused by the sudden change in refractive index by less than 0.1dB.

[0042] In the embodiments of this application, the waveguide refractive index difference between the core layer and the upper or lower cladding layer can be controlled to be 0.25~2% through a doping process, corresponding to a numerical aperture of 0.10~0.29. Furthermore, the input and output segments can have the same or different waveguide refractive index differences. When the input and output segments have different waveguide refractive index differences, the transmission characteristics of the waveguide mode can be guaranteed, for example, single transverse mode or multiple transverse modes.

[0043] For example, the numerical aperture range of the input and output segments is 0.12 to 0.15, which meets the waveguide single transverse mode and few-mode transmission characteristics in specific laser display applications.

[0044] In this embodiment, the input segment and the output segment are each configured with the same number of segments. Exemplarily, the number of input and output segments is related to the number of lasers. In practical applications, this number can be flexibly set and adjusted based on the number of lasers, and this embodiment does not limit this.

[0045] In the embodiments of this application, among the several input segments, the input segments are used to adapt the laser, and the interval between adjacent input segments is 50μm to avoid input crosstalk; among the several output segments, the interval between adjacent output segments is 20μm, and an isolation band is provided between adjacent output segments.

[0046] For example, the basis for determining the interval between adjacent output segments is as follows: (1) Three-dimensional trade-off between spacing, crosstalk and volume: Experimental tests show that the crosstalk is less than -30dB when the spacing is 20μm (satisfying signal purity and eliminating color crosstalk), and the area of ​​the silicon wafer (i.e. the final waveguide device) is reduced by 25% compared to the spacing of 30μm (while also taking into account miniaturization), and the crosstalk is improved by 5dB compared to the spacing of 10μm (avoiding interference). (2) Mode field matching: The mode field diameter of RGB (RED-GREEN-BLUE) laser is 5~8μm, and the 20μm interval ensures that there is no overlap between adjacent mode fields (overlap will lead to increased crosstalk), and is compatible with the lithography precision of CMOS (Complementary Metal-Oxide-Semiconductor) (20μm interval is easy to process, and the product yield is >95%). (3) Downstream adaptation: The pixel pitch of mainstream LCOS (Liquid Crystallization Silicon) is 10~20μm. A 20μm spacing beam can be directly matched with the pixel and can be directly combined without additional optical path adjustment, which can reduce light loss by 1~2dB.

[0047] In the embodiments of this application, such as Figure 4 As shown, the waveguide end face of the aforementioned waveguide device is coated with an antireflection film 13, which makes the overall beam combining loss from laser output to beam combining output less than 1dB. Furthermore, Figure 2 The diagonal lines filling the left, right, and bottom edges of the membrane are all part of the antireflective coating 13.

[0048] In the embodiments of this application, the antireflection film is an alternating SiO2 / TiO2 film layer, which makes the end face reflectivity less than 0.5%.

[0049] For example, the determination of the coating material in this application is based on the principle of thin film interference, specifically including: RGB laser wavelengths (red 635-640nm, green 520-530nm, blue 450-460nm) and thin film interference. (1) Refractive index matching: SiO2 (refractive index 1.46) is close to the core layer (SiO2, 1.46), and TiO2 (refractive index 2.35) forms a reasonable refractive index difference with air (1.0). The alternating stacking can cancel the end face reflection through "destructive interference". (2) Optical stability: Both materials have no absorption peak in the visible light band (absorption rate is less than 0.1%) and are resistant to high temperature (the melting point of TiO2 is 1843℃ and the melting point of SiO2 is 1713℃), which is suitable for the 60℃ working environment inside the optomechanical system. (3) Process compatibility: It is compatible with silicon-based waveguide CVD (chemical vapor deposition) process, and can be directly vapor deposited after waveguide preparation without changing equipment.

[0050] For example, this application can also further optimize the SiO2 / TiO2 alternating film layer based on RGB wavelength design, as follows: (1) Thickness customization: According to the formula 2nd=λ / 2 (n refers to the refractive index, d refers to the thickness, and λ refers to the target wavelength), the SiO2 layer is 100nm (adapted to the green wavelength of 523nm: 2×1.46×100≈584nm, taking into account the red and blue wavelengths), and the TiO2 layer is 80nm (2×2.35×80≈376nm, which covers all wavelengths of RGB after being stacked). (2) Layer optimization: The 4-layer structure (SiO2-TiO2-SiO2-TiO2) ensures that the reflectivity of each wavelength of RGB is 0.5%; (3) Calibration: After testing with a spectrophotometer, fine-tune the thickness. For example, the blue wavelength is 450nm and the reflectivity is 0.6%. In order to achieve the above 0.5%, adjust the outermost SiO2 from 100nm to 95nm.

[0051] For example, unlike the coating methods of existing technologies, this application uses an electron beam evaporation process to deposit four layers of alternating SiO2 / TiO2 films (SiO2 100nm / TiO2 80nm), which has the following advantages: (1) Higher precision: The thickness error of the film layer is less than 5nm, ensuring that the reflectivity of each wavelength of RGB is less than 0.5% (the error of traditional evaporation / sputtering is greater than 10nm, and the reflectivity under multiple wavelengths is easily greater than 1%). (2) Stronger adhesion: The film layer and the waveguide end face are atomically bonded, with a peel strength greater than 5N / cm, which is suitable for extreme environments of -40℃ to 85℃ (such as automotive-grade, AR scenarios, etc.), and the reflectivity change is less than 0.1% in the environment of -40℃ to 85℃, while traditional coatings are easy to fall off at high and low temperatures. (3) Full-band optimization: The 4-layer structure (SiO2-TiO2-SiO2-TiO2) covers the entire RGB laser band, ensuring that the reflectivity of each RGB wavelength is less than 0.5%. Therefore, the determination of the 4-layer structure can take into account the advantages of low reflectivity and process preparation, without the need to add extra film layers, which helps to avoid cracking of the anti-reflection film caused by excessive thickness due to too many layers.

[0052] Based on the antireflection coating, in this embodiment, a silicon dioxide waveguide device is fabricated using photolithography, chemical vapor deposition, and evaporation processes. The specific fabrication method of the waveguide device is as follows: (1) Substrate preparation: Selected <100> The crystal orientation is single-crystal silicon with a refractive index of 3.42, which plays a supporting role and is pretreated by RCA cleaning; (2) Lower cladding deposition: PECVD (plasma-enhanced chemical vapor deposition) was used, with SiH4:O2=1:4, process temperature 300℃, pressure 50Pa, and deposition thickness 3μm; (3) Core layer photolithography etching: Photoresist was used with a coating thickness of 1 μm, pre-baking at 90℃ for 30s, exposure dose of 100mJ / cm², development for 60s, and BOE etching solution (HF:NH4F=1:6) was used with an etching depth of 4 μm. (4) Upper cladding deposition: Using the same PECVD process as the lower cladding, a 3μm thick silicon dioxide layer was deposited at 300℃ and 50Pa with a SiH4:O2 ratio of 1:4; (5) Antireflection film deposition: Electron beam evaporation is used to deposit an antireflection film on the waveguide end face, wherein the SiO2 evaporation rate is 0.1 nm / s, the TiO2 evaporation rate is 0.05 nm / s, and the vacuum degree is 5×10^-5 Pa.

[0053] For example, in this embodiment, the waveguide device obtained based on the above-described fabrication method specifically includes the following components: (1) Silicon substrate, namely the above substrate layer 11: cuboid (10mm×8mm×500μm). <100> The crystal orientation is single-crystal silicon with a refractive index of 3.42, which serves as a support. (2) Silicon dioxide waveguide layer, namely the waveguide layer 12 described above: lower cladding (10mm×8mm×3μm, SiO2, refractive index 1.46), core layer, upper cladding (10mm×8mm×3μm, SiO2, refractive index 1.46); wherein, in a specific embodiment, the core layer includes: Input section: 8 parallel channels to accommodate 8 lasers. The channel width of each input section is 5~6μm, the thickness of each input section is 4μm, the length is 2mm, and the spacing is 50μm to avoid input crosstalk. Arc turning section: Each section is a 90° arc with a bending radius of 600~1500μm, a width of 5~8μm, and a linear gradient in the width direction. The thickness is 4μm, and the bending loss is less than 0.05dB / turn. Output section: 8 parallel channels, each 8~9μm wide, 4μm thick, 2mm long, with a spacing of 10~30μm. A 2~4μm wide SiO2 isolation band is provided between the channels to reduce crosstalk. (3) Laser interface: 8 rectangular interfaces, with the center aligned with the core layer of the input segment, with a deviation of less than 0.1 μm; (4) Anti-reflection film: 4 thin films at the input section interface and the end of the output section, with SiO2 100nm / TiO2 80nm alternating, and reflectivity less than 0.5%.

[0054] For example, the waveguide device in this application is determined based on the following criteria: (1) Miniaturization requirement: Through the 90° arc turn design, the area of ​​the silicon wafer (i.e. the final waveguide device) is reduced by more than 40% compared with the traditional straight layout (taking 8 lasers as an example, the specific size of the waveguide device with the straight layout is 12mm×10mm, and the specific size of the waveguide device with the 90° arc turn layout is 10mm×8mm). (2) Balance between low loss and low crosstalk: Based on the "spacing-crosstalk" quantization relationship (crosstalk less than -30dB with 20μm spacing, less than -25dB with 10μm spacing, and less than -35dB with 30μm spacing), and combined with the area cost of silicon wafer (i.e. the final waveguide device), 20μm is selected as the optimal spacing between adjacent output segments; (3) Process compatibility: The structure is compatible with CMOS standard processes (minimum linewidth of 2μm for photolithography, radius of curvature of 600~1500μm for easy etching, and product yield greater than 95%). (4) Scalability: The 50μm input segment spacing can accommodate 3 to 8 lasers. When reducing the number of lasers, only the extra input channels need to be blocked, without modifying the overall structure.

[0055] In summary, taking the waveguide device of this application as an example with an installation scenario of 8 lasers, compared with existing discrete component beam combining and planar waveguide beam combining, its performance differences in terms of structural volume, transmission loss, beam combining loss, coupling loss, coupling efficiency, crosstalk between adjacent output sections, and assembly cost (relative value) are shown in Table 1: Table 1. Performance Comparison of This Application with Discrete Component Beamforming and Planar Waveguide Beamforming

[0056] Preferably, in the embodiments of this application, the waveguide device described above is applied to multi-beam combining in laser displays.

[0057] Preferably, in the embodiments of this application, the method of applying the waveguide device includes the following steps: 1. A waveguide device is configured with more than one laser; wherein the more than one laser includes at least one set of RGB semiconductor lasers; 2. Directly couple more than one laser to the waveguide device; 3. More than one laser emits a beam, allowing the beam to propagate along the waveguide device; 4. Laser display is achieved by controlling the speckle suppression and output beam of the waveguide device.

[0058] Preferably, in the embodiments of this application, in the more than one laser mentioned above, the wavelength difference of the same color laser is 0.5~5nm.

[0059] For example, the configuration of the laser in this application is based on the following specific situations: In one possible implementation, the laser is configured based on brightness requirements: (1) Low brightness: For example, a portable micro projector with 500 lumens; equipped with three lasers, specifically: one each of R semiconductor laser, G semiconductor laser and B semiconductor laser, with a single tube power of 50~100mW and a total power of 150~300mW, which can be used to meet basic display requirements; (2) Medium brightness: For example, a home laser TV with 1000 lumens; equipped with six lasers, specifically two each of R semiconductor lasers, G semiconductor lasers and B semiconductor lasers, with a single tube power of 100~150mW and a total power of 600~900mW, which doubles the power compared to low brightness; (3) High brightness: For example, vehicle-mounted HUD (Head-Up Display) with 1500 lumens; equipped with eight lasers, including two R semiconductor lasers, three G semiconductor lasers and three B semiconductor lasers, with a single tube power of 150~200mW and a total power of 1.0~1.5W, which can then be used to support high brightness projection.

[0060] In other possible implementations, multiple lasers are configured sequentially: Combination Figure 2 As shown, the output segments are arranged flexibly. The typical order of LD1-LD8 is GGBBGBRR, which is used to adapt to optical engine design. In other implementations, other order configurations can also be implemented based on the application scenario.

[0061] In another possible implementation, the laser is configured based on color gamut requirements: (1) Basic color gamut (Rec (Recommendation).709, 72% NTSC (National Television Systems Committee): Configured with three standard wavelength lasers; (2) Wide color gamut (BT (Broadcasting Television).2020, 110% NTSC): Configure 6~8 lasers (multiple wavelengths of the same color superimposed, such as green wavelength 520nm+523nm, to fill the color gamut gap).

[0062] In another possible implementation, the laser is configured based on cost and integration: (1) Low cost: For example, entry-level micro projectors; configuring three lasers can reduce the difficulty of coupling the lasers with the waveguide device, reducing the cost by 30%; (2) High integration: For example, AR head-mounted display with a volume of less than 1 cm³; configured with eight lasers, combined with the disclosure of this application, by optimizing the arc turning structure and by the compact output layout, the volume is ensured not to exceed the limit.

[0063] For example, this application uses wavelength diversity or polarization multiplexing to perform the above-mentioned speckle suppression modulation to suppress laser speckle and make the speckle contrast of the output beam less than 5%, while the traditional scheme without speckle suppression is usually 15-20%.

[0064] For example, specific methods for speckle suppression modulation through wavelength diversity include: (1) Laser selection: For lasers of the same color, tunable LDs (Laser Diodes) are selected (for example, the red wavelength corresponding to R semiconductor lasers is 635~640nm, the green wavelength corresponding to G semiconductor lasers is 520~525nm, and the blue wavelength corresponding to B semiconductor lasers is 450~455nm). The wavelength difference of 0.5~5nm can be achieved by fine adjustment of 5~10mA current. (2) Channel allocation: Lasers of the same color but different wavelengths are coupled to adjacent input ports, and the output segments are spatially superimposed; (3) Suppression principle: Based on the coherence length formula Lc=λ² / Δλ (Lc refers to the coherence length, λ refers to the center wavelength, and Δλ refers to the wavelength difference), the larger the wavelength difference, the shorter the coherence length (when Δλ=3nm, Lc≈134μm, the display optical path length is 10~50cm). After superposition, the coherence is reduced, and the speckle contrast is reduced to 4.2% (measured value), which is less than the 18.7% of the traditional unsuppressed scheme.

[0065] For example, specific methods for speckle suppression modulation via polarization multiplexing include: (1) Structural integration: The same color beam is divided into p-wave and s-wave, and simultaneously coupled into the waveguide output; (2) Superposition control: The two polarized beams are transmitted in parallel and the phase difference is approximately π / 2. The orthogonal polarization states further reduce coherence.

[0066] For example, this application uses a collimating lens combined with LCOS to project directly, or uses a microlens array to collimate and then couple into an optical fiber for transmission to achieve the above-mentioned output spot control.

[0067] For example, the specific method of controlling the output light spot by directly projecting through a collimating lens in combination with LCOS includes: the collimating lens is an aspherical lens (e.g., with a focal length of 5mm and a numerical aperture of 0.3), which is matched with the pixel pitch of the LCOS chip of 10~20μm. The output beam with a 20μm interval can directly correspond to the LCOS pixel without beam expansion / contraction, which can reduce 1~2dB of additional light loss. For example, the specific method of controlling the output beam spot by collimating and recoupling the microlens array into the optical fiber transmission includes: for example, the microlens array adopts a 1×8 array, wherein the diameter of a single lens is 100μm and the numerical aperture is 0.2, and the parallel output beam is coupled to an 8-core optical fiber with a core diameter of 50μm and a coupling efficiency of more than 90%, which is suitable for long-distance transmission scenarios, such as engineering projection.

[0068] Through the disclosure of the above embodiments, based on the multi-beam combining technology of silicon dioxide waveguides, this application minimizes the silicon wafer area occupied by planar integration and arc-shaped turning design, achieving miniaturized integration; it can be applied to the field of portable projection, and by integrating into a mobile phone module, it can achieve a volume of less than 1cm³ and a brightness of 500 lumens; it can also be applied to AR / VR displays as a Micro-LED backlight source to achieve high-resolution near-eye display; further, it can be applied to automotive displays, adapting to automotive projection and HUB systems to achieve a combination of high reliability and miniaturization; and in the medical field, it can realize endoscopic visualization and achieve precise minimally invasive treatment.

[0069] This application also discloses a laser display device, including the waveguide device described above, and further including at least one set of RGB semiconductor lasers and a speckle suppression module.

[0070] The RGB semiconductor laser is directly coupled to the input section of the waveguide device. An RGB semiconductor laser is a semiconductor device capable of directly emitting red, green, and blue primary color laser light, or a laser module composed of three independent red, green, and blue semiconductor laser chips tightly integrated together. Based on the structural design of the waveguide device, the spacing of the output section of the waveguide device is adapted to the package spacing of the RGB semiconductor laser, thus achieving beam combining without additional optical path adjustments.

[0071] The speckle suppression module is directly coupled to the output section of the waveguide device, and achieves a speckle contrast of less than 5% through wavelength diversity or polarization multiplexing.

[0072] The above embodiments are merely illustrative of the technical concept and features of the present invention, intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly, and should not be construed as limiting the scope of protection of the present invention. It will be apparent to those skilled in the art that the present invention is not limited to the details of the above exemplary embodiments, and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects. The scope of the present invention is defined by the appended claims rather than the foregoing description, and thus all changes falling within the meaning and scope of the equivalents of the claims are intended to be included within the invention.

[0073] The above description is merely an exemplary embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A waveguide device, characterized in that, It includes a substrate layer and a waveguide layer superimposed on the substrate layer, the waveguide layer including a lower cladding layer, a core layer and an upper cladding layer superimposed in sequence; The core layer includes an input segment and an output segment, as well as an arc-shaped turning segment located between the input segment and the output segment. The laser beam enters from the input segment and exits from the output segment. The arc-shaped turning segment enables the laser beam to turn at a preset angle from the input to the output direction.

2. The waveguide device according to claim 1, characterized in that, The bending radius of the arc turning segment is 600~1500μm.

3. The waveguide device according to claim 1, characterized in that, The preset angle is 30° to 150°.

4. The waveguide device according to claim 1, characterized in that, The input segment has a channel width of 5~6μm, and the output segment has a channel width of 8~9μm.

5. The waveguide device according to claim 4, characterized in that, The arc turning segment is constructed as a linear gradient structure, which makes the coupling efficiency of the laser beam greater than 90% and the coupling loss less than 0.5dB.

6. The waveguide device according to claim 5, characterized in that, The channel width in the linear gradient structure gradually increases from the input segment to the output segment, with an increase of 0.6~0.7μm for every 100μm of channel width.

7. The waveguide device according to claim 1, characterized in that, The input segment and the output segment are each configured with the same number of segments, the spacing between adjacent output segments is 10~30μm, and an isolation strip is provided between adjacent output segments.

8. The waveguide device according to claim 1, characterized in that, The waveguide end face of the waveguide device is coated with an antireflection film; the antireflection film has a reflectivity change of less than 0.1% in an environment of -40℃ to 85℃ and a peel strength greater than 5N / cm.

9. The waveguide device according to claim 8, characterized in that, The antireflective film is an alternating SiO2 / TiO2 film layer.

10. The application of the waveguide device according to any one of claims 1 to 9, characterized in that, include: The waveguide device is used in multi-beam beam combining in laser displays. The output segment spacing of the waveguide device is adapted to the packaging spacing of the laser, and beam combining can be achieved without additional optical path adjustment. It also includes the application of the waveguide device in beam shaping, laser equipment, optical communication, medical, and automotive applications.

11. The application of the waveguide device according to claim 10, characterized in that, The application methods of the waveguide device include: The waveguide device is configured with more than one laser; wherein the more than one laser includes at least one group of RGB semiconductor lasers; The more than one laser is directly coupled to the waveguide device; The more than one laser emits a beam of light, causing the beam to propagate along the waveguide device; Laser display is achieved by controlling the speckle suppression and output beam of the waveguide device.

12. The application of the waveguide device according to claim 11, characterized in that, In the more than one laser, the wavelength difference between lasers of the same color is 0.5~5nm.

13. A laser display device, characterized in that, include: The waveguide device according to any one of claims 1 to 9; At least one set of RGB semiconductor lasers, wherein the RGB semiconductor lasers are directly coupled to the input section of the waveguide device; The speckle suppression module is directly coupled to the output section of the waveguide device, and achieves a speckle contrast of less than 5% through wavelength diversity or polarization multiplexing.

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