A reflector and optical device

Abstract

The embodiment of the application provides a reflector and an optical device, comprising a substrate, an epitaxial structure, a ridge waveguide structure and a filling material layer, the epitaxial structure is on the substrate and has a covered area and an uncovered area on the side away from the substrate, the ridge waveguide structure is arranged on the covered area of the epitaxial structure, one end of the filling material layer is arranged on the uncovered area of the epitaxial structure, and the other end extends to the substrate and extends into the substrate, a high reflection band is formed in a target wave band through material optical characteristic difference, the high reflection band is formed by arranging the filling material layer on the uncovered area of the epitaxial structure, the light field energy expansion is effectively limited, high-order mode and ghost mode resonance are inhibited, the light beam quality and mode stability are improved, and the advantages of inhibiting high-order mode excitation, improving light beam quality and enhancing mode stability are achieved.

Description

Technical Field

[0001] This application relates to the technical field of lasers, and more particularly to a reflector and optical device. Background Technology

[0002] The resonant cavity of the laser consists of a pair of parallel cleavage surfaces. Under high current injection conditions, population inversion and stimulated recombination occur in the active region, resulting in the emission of a large number of photons with the same frequency and phase, thus achieving high-power output. It is worth noting that the laser's output power and beam quality are closely related to the stability of the optical field modes within the resonant cavity. Under ideal operating conditions, the laser's optical field energy is primarily concentrated in the waveguide center region below the ridge, which not only ensures a small beam divergence angle and a regular far-field spot but also helps reduce mode noise and improve power stability.

[0003] Reference Figure 1 , Figure 2 Traditional lasers, due to their excessively large ridge waveguide width (>5 μm), significant spatial hole burning effect, and structural defects in the ridge waveguide (such as interface roughness and material inhomogeneity), are prone to exciting higher-order modes within the device. This directly leads to a significant increase in beam divergence angle and beam splitting in the far field. Furthermore, when the refractive index distribution of the epitaxial structure is poorly designed (e.g., a small refractive index difference between the waveguide layer and the confinement layer), the optical energy can penetrate the confinement layer and extend into the substrate, forming "ghost mode" resonances in thick substrates. This effect not only causes a rise in local device temperature and dynamic distortion of the refractive index distribution, but also interferes with active region mode matching, compromising laser mode stability, such as increasing spectral linewidth and exacerbating power jitter. In addition, the higher-order mode optical field directly degrades the laser beam quality, severely reducing the laser's spatial coherence and fiber coupling efficiency.

[0004] Therefore, there is an urgent need for a reflector that can effectively shield higher-order modes and "ghost mode" distributions of lasers, thereby improving the reliability of the device and the beam quality. Summary of the Invention

[0005] This application provides a reflector and optical device that can effectively shield the higher-order modes and "ghost mode" distribution of a laser from improving the reliability of the device and the beam quality.

[0006] In a first aspect, embodiments of this application provide a reflector, including:

[0007] Substrate;

[0008] An epitaxial structure is disposed on a substrate, and the side of the epitaxial structure facing away from the substrate has a covered area and a non-covered area;

[0009] A ridge waveguide structure, wherein the ridge waveguide structure is disposed on the coverage area of ​​the epitaxial structure;

[0010] a filling material layer, which is arranged on the uncovered area of the epitaxial structure, so that the reflector forms a high reflection band in a target wave band.

[0011] In a possible implementation, the filling material layer has one end located on the uncovered area of the epitaxial structure and the other end extending towards and into the substrate.

[0012] In a possible implementation, the filling material layer has a plurality of layers, which are arranged on the uncovered area in intervals;

[0013] and the thickness of two adjacent filling material layers is λ / 4n, n is the refractive index of the filling material, the interval between two adjacent filling material layers is t, t is λ / 4m, m is the refractive index of the interval layer, and λ is the target wavelength of the reflector.

[0014] In a possible implementation, the epitaxial structure includes an electron supply layer and a derivative layer, the electron supply layer is arranged on the substrate, the electron supply layer has a first area and a second area, the derivative layer is arranged on the first area of the electron supply layer, the second area serves as the uncovered area, and the filling material layer is arranged on the second area of the electron supply layer.

[0015] The derivative layer has the covered area, and the ridge waveguide structure is arranged on the derivative layer and located on the covered area.

[0016] In a possible implementation, the epitaxial structure includes an electron supply layer and a derivative layer, the electron supply layer is arranged on the substrate, the derivative layer has the covered area and the uncovered area on a side face opposite to the supply layer, the filling material layer is arranged on the uncovered area of the derivative layer, and the ridge waveguide structure is arranged on the derivative layer and located on the covered area.

[0017] In a possible implementation, the filling material layer 111 is a low-refractive medium layer.

[0018] In a possible implementation, the derivative layer includes an N-type cladding layer, an N-type waveguide layer, a quantum well active layer, a P-type waveguide layer, an electron blocking layer, and a P-type cladding layer.

[0019] The ridge waveguide structure is arranged on the P-type cladding layer.

[0020] And / or, the material of the N-type cladding layer is AlInGaN or AlGaAs, and the thickness of the N-type cladding layer is greater than or equal to 0.1 μm and less than or equal to 3 μm;

[0021] And / or, the material of the N-type waveguide layer is AlInGaN or AlGaAs, and the thickness of the N-type waveguide layer is greater than or equal to 0.1 μm and less than or equal to 0.5 μm;

[0022] And / or, the material of the quantum well active layer is alternately grown AlInGaN well layer-AlInGaN barrier layer or alternately grown InGaAs well layer-AlGaAs barrier layer, and the thickness of the quantum well active layer is greater than or equal to 0.02 μm and less than or equal to 0.5 μm;

[0023] And / or, the material of the P-type waveguide layer is AlInGaN or AlGaAs, and the thickness of the P-type waveguide layer is greater than or equal to 0.1 μm and less than or equal to 0.5 μm;

[0024] And / or, the material of the electron blocking layer is AlInGaN or AlGaAs, and the thickness of the electron blocking layer is greater than or equal to 0.1 μm and less than or equal to 0.3 μm;

[0025] And / or, the material of the P-type cladding layer is AlInGaN or AlGaAs, and the thickness of the P-type cladding layer is greater than or equal to 0.1 μm and less than or equal to 3 μm.

[0026] In a possible implementation, the ridge waveguide structure includes a hole supply layer and an ohmic contact layer which are arranged in a stack, and the hole supply layer is located on the P-type cladding layer;

[0027] And / or, the material of the hole supply layer is AlInGaN or AlGaAs, and the thickness of the hole supply layer is greater than or equal to 0.3 μm and less than or equal to 1 μm;

[0028] And / or, the material of the ohmic contact layer is AlInGaN or AlGaAs, and the thickness of the ohmic contact layer is greater than or equal to 95 nm and less than or equal to 105 nm.

[0029] In a possible implementation, the ridge waveguide structure includes a hole supply layer and an ohmic contact layer which are arranged in a stack, and the hole supply layer is located on the P-type cladding layer;

[0030] And / or, the material of the first electrode is Cr / Au, Ti / Au or Ni / Au;

[0031] And / or, the material of the second electrode is Cr / Au, Ti / Au or Ni / Au;

[0032] and / or the reflectivity of the reflective film is 50%-100%;

[0033] and / or the reflectivity of the antireflection film is less than or equal to 90%.

[0034] In a second aspect, the embodiments of the present application provide an optical device, comprising the reflector described above.

[0035] The reflector and the optical device provided by the embodiments of the present application effectively limit the expansion of the optical field energy, suppress the resonance of high-order modes and ghost modes, improve the beam quality and the mode stability, and have the advantages of suppressing the excitation of high-order modes, improving the beam quality, and enhancing the mode stability. BRIEF DESCRIPTION OF DRAWINGS

[0036] The accompanying drawings, which are incorporated herein and form a part of the specification, illustrate the embodiments of the present application and, together with the description, serve to explain the principles of the present application.

[0037] Figure 1 A schematic diagram of a side view cross-sectional structure of a conventional laser introduced in the background;

[0038] Figure 2 A schematic diagram of a front view cross-sectional structure of a conventional laser introduced in the background;

[0039] Figure 3 A schematic diagram of a front view cross-sectional structure of a reflector of the present application;

[0040] Figure 4 A schematic diagram of a top view structure of a reflector of the present application;

[0041] Figure 5 A schematic diagram of a side view cross-sectional structure of a reflector of the present application;

[0042] Figure 6 A schematic diagram of a front view cross-sectional structure of an epitaxial structure of a reflector of the present application;

[0043] Figure 7 A schematic diagram of a front view cross-sectional structure of an etched ridge waveguide of a reflector of the present application;

[0044] Figure 8 A schematic diagram of a structure of an etched substrate and an electron supply layer of a reflector of the present application;

[0045] Figure 9 A schematic diagram of a structure of a generated filling material of a reflector of the present application;

[0046] Figure 10The simulation results of a conventional laser introduced in the background art and a reflector and a preparation method thereof of the present application are compared, wherein, Figure 10 (a) in the above (a) is a laser light field distribution of a laser with poor light confinement ability introduced in the background art; Figure 10 (b) in the above (b) is a laser light field distribution of a reflector and a preparation method thereof of the present application.

[0047] The reference signs are explained as follows: 101, substrate; 102, electron supply layer; 103, N-type cladding layer; 104, N-type waveguide layer; 105, quantum well active layer; 106, P-type waveguide layer; 107, electron blocking layer; 108, P-type cladding layer; 109, hole supply layer; 110, ohmic contact layer; 111, filling material layer; 112, first electrode; 113, second electrode; 114, reflective film; 115, antireflection film.

[0048] The specific embodiments of the present application have been shown by the above drawings, and will be described in more detail hereinafter. These drawings and the written description are not intended to restrict the scope of the present application concept by any means, but to illustrate the present application concept to those skilled in the art by referring to specific embodiments. DETAILED DESCRIPTION

[0049] The exemplary embodiments will be described in detail herein with reference to the accompanying drawings. In the following description, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments are not representative of all embodiments consistent with the present application. Rather, they are merely examples of devices and methods consistent with some aspects of the present application as detailed in the appended claims.

[0050] The resonant cavity of the laser is formed by a pair of parallel cleaved surfaces. Under the condition of large current injection, particle inversion is achieved in the active region and stimulated recombination occurs, thereby radiating a large number of photons of the same frequency and phase and achieving high-power output. The output power and beam quality of the laser are closely related to the stability of the light field mode in the resonant cavity. In the ideal working state, the light field energy of the laser is highly concentrated in the waveguide center region below the ridge, which not only ensures a small beam divergence angle and a regular far-field spot, but also helps to reduce mode noise and improve power stability.

[0051] However, when the ridge waveguide width is too large or the refractive index distribution of the epitaxial structure is unreasonable, high-order mode and ghost mode resonances will occur, thereby affecting the beam quality. For example, during the working process of a semiconductor laser, the light field energy diffuses from the waveguide layer to the substrate, which will cause the far-field spot to split and the power stability to decrease.

[0052] In view of the above status and problems, the application provides a reflector and an optical device, which comprises a substrate, an epitaxial structure, a ridge waveguide structure and a filling material layer. The epitaxial structure is arranged on the substrate and has a covered area and an uncovered area on the side away from the substrate. The ridge waveguide structure is arranged on the covered area of the epitaxial structure. One end of the filling material layer is arranged on the uncovered area of the epitaxial structure, and the other end extends to the substrate and into the substrate. A high reflection band is formed in a target wave band by the difference in material optical characteristics. The high reflection band is formed by arranging the filling material layer on the uncovered area of the epitaxial structure, which effectively limits the expansion of optical field energy, suppresses high-order mode and ghost mode resonance, improves the beam quality and mode stability, and has the advantages of suppressing high-order mode excitation, improving beam quality and enhancing mode stability.

[0053] The technical solutions of the application and how the technical solutions solve the above technical problems will be described in detail below with specific examples. The following specific examples can be combined with each other, and the same or similar concepts or processes can not be described again in some examples. The embodiments of the application will be described below with reference to the drawings.

[0054] Embodiment 1

[0055] With reference to Figure 3 、 Figure 4 、 Figure 5 , the embodiment of the application provides a reflector comprising a substrate 101, an epitaxial structure, a ridge waveguide structure and a filling material layer 111.

[0056] The substrate 101 can be made of GaN or GaAs, and has a thickness greater than or equal to 200 nm and less than or equal to 3 μm.

[0057] The epitaxial structure is arranged on the substrate 101 and forms a covered area and an uncovered area on the side away from the substrate 101. The ridge waveguide structure is arranged on the covered area of the epitaxial structure. The filling material layer 111 is arranged on the uncovered area of the epitaxial structure.

[0058] Specifically, when the laser propagates in the ridge waveguide structure, the interface between the filling material layer 111 and the adjacent epitaxial structure and substrate 101 will produce periodic reflection. This reflection forms an effective optical field limiting boundary in the uncovered area, which prevents the optical field energy from spreading to the non-waveguide area. For the high-order mode that may be generated, the light field distribution is more likely to reach the filling material layer 111 area. At the same time, the refraction index between the filling layer and the substrate 101 is deflected, which can block the penetration of the optical field to the substrate and eliminate the physical conditions for ghost mode resonance.

[0059] Compared with the related art, the conventional scheme suppresses the stray mode by optimizing the waveguide width or adjusting the epitaxial layer composition, while the present application forms a passive reflection mechanism by arranging the filling material layer 111 in the uncovered area without changing the main waveguide structure. Compared with the modification of the complex epitaxial structure, the overall structure is simple, and the laser high-order mode oscillation is effectively suppressed, and the light field energy leakage path to the substrate 101 is blocked.

[0060] The embodiment of the present application further proposes that one end of the filling material layer 111 is located in the uncovered area of the epitaxial structure, and the other end extends towards the substrate 101 and extends into the substrate 101.

[0061] The filling material layer 111 is made of metal material or transparent conductive oxide, for example, an Al / Ni alloy layer or an ITO layer with a predetermined shape is formed by photolithography and etching process. The filling material layer 111 is arranged in the uncovered area of the epitaxial structure and extends into the substrate 101, which can enhance the light field restriction capability and block the propagation path of the light wave to the substrate 101.

[0062] Specifically, when the light wave propagates to the uncovered area, the composite structure formed by the filling material layer 111, the epitaxial structure and the substrate 101 will produce total reflection effect, and the depth of the filling material layer 111 extending into the substrate 101 can destroy the resonance condition of the light wave in the substrate 101, thereby effectively suppressing the formation of high-order mode and ghost mode.

[0063] Compared with the related art, the conventional scheme suppresses the stray mode by optimizing the waveguide width or adjusting the epitaxial layer composition, which cannot block the propagation path of the light wave in the substrate 101. The present application extends the filling material layer 111 to the substrate 101, and builds a continuous light field reflection interface in the vertical direction, so that the light wave is effectively limited in the horizontal and vertical directions, solves the mode interference problem caused by light leakage in the substrate 101 in the conventional structure, effectively blocks the propagation path of the light wave in the substrate 101, eliminates the physical conditions required for ghost mode resonance, and enhances the horizontal light field restriction capability, so that the light field energy of the laser is stably concentrated in the ridge waveguide area during operation, which significantly improves the beam divergence angle and far field spot shape.

[0064] The embodiment of the present application further proposes that the number of filling material layers 111 is multiple, and the multiple filling material layers 111 are arranged at intervals on the uncovered area, and the thickness of the adjacent two filling material layers 111 is λ / 4n, n is the refractive index of the filling material, the interval between the filling material layers is t, t is λ / 4m, m is the refractive index of the interval layer, and λ is the target wavelength of the reflector.

[0065] The refractive index of the interval layer refers to the refractive index of the layer material located between two adjacent filling material layers 111, for example, the interval is located between two adjacent filling material layers 111 of the substrate 101, and the refractive index of the interval layer is the refractive index of the material of the substrate 101.

[0066] Specifically, the interval between adjacent layers is set according to the target wavelength. When the incident light is reflected at the interface of the filling material layer 111, the optical path difference of the adjacent reflected light forms constructive interference, thereby forming a high reflection band at the target wavelength. This periodic structure can effectively suppress the propagation of high-order modes in the non-waveguide region, and block the diffusion of the optical field to the substrate 101 to form a ghost mode.

[0067] Referring to Figure 10 , Figure 10 The abscissa and ordinate in (a) and (b) in the figure respectively represent the length and width of the optical field distribution, in units of microns. As can be seen from the figure, compared with the related art, the traditional reflection structure uses a continuous dielectric layer to cover the non-waveguide region, which cannot form a selective reflection band, resulting in low reflection efficiency of a wide spectrum. And according to the target wavelength, the filling material layer 111 with corresponding length, width and interval can be used to achieve narrowband high reflection for the target wavelength, which can effectively suppress the excitation of high-order modes of the laser and block the leakage of optical field energy to the substrate 101 to form a ghost mode.

[0068] Referring to Figure 3 , Figure 4 , Figure 5 The embodiment of the present application further provides a reflector comprising a substrate 101, an epitaxial structure, a ridge waveguide structure and a filling material layer 111. The epitaxial structure comprises an electron supply layer 102 and a derived layer. The electron supply layer 102 is arranged on the substrate 101 and is divided into a first region and a second region. The derived layer is arranged in the first region of the electron supply layer 102. The second region is arranged with the filling material layer 111 as a non-covered region. The covered region of the derived layer is arranged with the ridge waveguide structure.

[0069] The electron supply layer 102 forms a potential difference through a carrier concentration gradient to drive the migration of carriers. The material of the electron supply layer 102 can be AlInGaN or AlGaAs. The thickness of the electron supply layer 102 is greater than or equal to 0.1 μm and less than or equal to 3 μm.

[0070] The derived layer is a composite functional layer composed of a plurality of heterostructures, which forms an optical field limiting structure by stacking materials with different refractive indices.

[0071] Specifically, the first region of the electron supply layer 102 forms a light field restriction region through the derivative layer, and the ridge waveguide structure guides the main mode light field propagation in the region, and the second region of the electron supply layer 102 forms a reflection barrier through the filling material layer 111, which blocks the diffusion of the high-order mode light field to the substrate 101. The derivative layer concentrates the light field energy under the ridge waveguide, and the filling material layer 111 reflects the light field escaping to the non-covered region back to the waveguide core region through the high reflection characteristic, thereby suppressing the excitation of the high-order mode and the ghost mode.

[0072] The embodiment of the present application decouples the light field restriction and the reflection function through the partition design of the electron supply layer 102 and the derivative layer, the filling material layer 111 directly acts on the non-covered region of the electron supply layer 102, can block the path of the light field energy leakage to the substrate 101, effectively restricts the distribution of the light field energy in the center region of the ridge waveguide, reduces the excitation probability of the high-order mode, suppresses the resonance of the ghost mode in the substrate 101, thereby improving the beam quality and mode stability of the laser, and the synergistic effect of the filling material layer 111 and the electron supply layer 102 can reduce the lateral diffusion of the light field energy, improve the far-field spot shape, and at the same time reduce the local temperature rise effect caused by energy leakage.

[0073] The embodiment of the present application further proposes that the filling material layer 111 is a medium layer with low refractive index, in the embodiment, the low refractive index refers to 1-2, and silicon oxide, aluminum oxide and the like can be used.

[0074] Specifically, the filling material layer 111 is arranged in the non-covered region, the optical constant of the material forms a refractive index difference with the surrounding epitaxial structure, and a high reflection band is established in the target waveband through the interface reflection effect.

[0075] The present application can flexibly select the filling material for different target wavebands, suppress the high-order mode, enhance the reflection band stability, thereby improve the beam quality of the laser and reduce the mode noise, and improve the working reliability of the device.

[0076] The embodiment of the present application further proposes a reflector, the derivative layer of which includes an N-type cladding layer 103, an N-type waveguide layer 104, a quantum well active layer 105, a P-type waveguide layer 106, an electron blocking layer 107, and a P-type cladding layer 108, and the ridge waveguide structure is arranged on the P-type cladding layer 108.

[0077] The N-type cladding layer 103 is a semiconductor layer formed by doping to form an electron transport channel, the N-type cladding layer 103 is grown by metal organic chemical vapor deposition on the substrate 101 to realize AlInGaN or AlGaAs material, and the thickness is greater than or equal to 0.1 μm and less than or equal to 3 μm, so as to balance the carrier injection efficiency and the light field restriction capability.

[0078] The N-type waveguide layer 104 is a structure layer for restricting the lateral expansion of the light field, and the material of the N-type waveguide layer 104 can be AlInGaN or AlGaAs formed by molecular beam epitaxy, and the thickness is greater than or equal to 0.1 μm and less than or equal to 0.5 μm.

[0079] The quantum well active layer 105 is a composite area for generating stimulated radiation, and the material of the quantum well active layer 105 is an AlInGaN well layer-AlInGaN barrier layer alternately grown or an InGaAs well layer-AlGaAs barrier layer alternately grown, and the thickness is greater than or equal to 0.02 μm and less than or equal to 0.5 μm, and the carrier recombination efficiency can be adjusted.

[0080] The P-type waveguide layer 106 is a complementary structure layer for forming an optical waveguide together with the N-type waveguide layer 104, and the material of the P-type waveguide layer 106 is AlInGaN or AlGaAs, and the thickness is greater than or equal to 0.1 μm and less than or equal to 0.5 μm, so as to maintain the mode symmetry.

[0081] The electron blocking layer 107 is a functional layer for inhibiting electron overflow, and the material of the electron blocking layer 107 is AlInGaN or AlGaAs, and the thickness is greater than or equal to 0.1 μm and less than or equal to 0.3 μm, so as to realize carrier confinement.

[0082] The P-type cladding layer 108 is a semiconductor layer for forming light field restriction by hole injection, and the material of the P-type cladding layer 108 is AlInGaN or AlGaAs, and the thickness is greater than or equal to 0.1 μm and less than or equal to 3 μm, so as to match the optical restriction requirement.

[0083] Specifically, by constructing a derived layer including a six-layer heterostructure, the refractive index gradient distribution of each layer material forms a light field restriction potential barrier, the N-type cladding layer 103 and the P-type cladding layer 108 form a symmetrical optical restriction structure, the quantum well active layer 105 is clamped between the double waveguide layers to form a gain region, the electron blocking layer 107 inhibits carrier leakage, and after the thickness of each layer is optimized, the light field energy can be concentrated in the waveguide center region, and the generation of ghost modes by the expansion of the light field to the substrate 101 is avoided. The selection of the AlInGaN or AlGaAs material system ensures the lattice matching of each layer, and reduces the scattering loss caused by the interface defects. The ridge waveguide structure is arranged on the top of the P-type cladding layer 108, and the two-dimensional light field restriction is realized through the lateral refractive index difference.

[0084] Compared with the traditional single restriction layer structure, the derived layer design formed by the heterostructure of the present application can enhance the lateral light field restriction capability, and the synergistic effect of the electron blocking layer 107 and the double waveguide layers can improve the carrier injection efficiency, so as to effectively limit the expansion range of the light field in the lateral and longitudinal directions, inhibit the generation of high-order modes and ghost mode resonances, and highly concentrate the light field energy under the ridge waveguide, thereby improving the beam divergence characteristics and far field spot quality.

[0085] The embodiment of the present application further provides a reflector, which comprises a hole supply layer 109 and an ohmic contact layer 110 arranged in a stack, and the hole supply layer 109 is located on the P-type cladding layer 108.

[0086] It should be noted that the hole supply layer 109 is a semiconductor layer for optimizing the carrier injection efficiency, the material of the hole supply layer 109 can be AlInGaN or AlGaAs, the thickness of the hole supply layer 109 is greater than or equal to 0.3 μm and less than or equal to 1 μm, which can ensure sufficient carrier transmission capacity and avoid the imbalance of structural stress caused by excessive thickness.

[0087] It should be noted that the ohmic contact layer 110 is a functional layer of low-resistance metal-semiconductor contact, the material of the ohmic contact layer 110 is high-doped AlInGaN or AlGaAs, and the thickness of the ohmic contact layer 110 is greater than or equal to 95 nm and less than or equal to 105 nm, which can reduce the contact resistance while maintaining the interface flatness.

[0088] Specifically, the hole supply layer 109 is in direct contact with the P-type cladding layer 108 to form a carrier transmission channel, the AlInGaN or AlGaAs material of the hole supply layer 109 is lattice matched with the lower layer material, which can reduce the carrier scattering caused by interface defects, and the hole injection path and electrode contact characteristics are effectively optimized through the material matching and thickness coordination design.

[0089] The present application can significantly reduce the operating voltage and heat loss while maintaining the compact structure, and the selection of the AlInGaN or AlGaAs material system can form a continuous band structure with the epitaxial layer, avoid the carrier potential barrier generated at the interface of the traditional heterogeneous material, effectively improve the carrier injection uniformity of the ridge waveguide structure, reduce the joule heat effect caused by the electrode contact resistance, thereby inhibit the refractive index distortion caused by local temperature rise, help to maintain the stable distribution of the optical field energy in the center of the waveguide, reduce the high-order mode excitation phenomenon, and finally improve the beam quality and output power stability of the laser.

[0090] The embodiment of the present application further provides that the front end surface of the reflector in the first direction (x direction in the figure) is provided with a reflective film 114, the epitaxial structure and the ridge waveguide structure in the first direction are provided with an anti-reflection film 115, the ridge waveguide structure is provided with a first electrode 112, and the bottom of the substrate 101 is provided with a second electrode 113.

[0091] The material of the first electrode 112 is Cr / Au, Ti / Au or Ni / Au, and the material of the second electrode 113 is Cr / Au, Ti / Au or Ni / Au. Specifically, the first electrode 112 is an anode electrode, and the second electrode 113 is a cathode electrode, which are respectively arranged on the top of the ridge waveguide and the bottom of the substrate 101. The anode electrode and the ridge waveguide form an ohmic contact to realize hole injection, and the cathode electrode and the substrate 101 form an electron injection path, and the double-electrode structure ensures effective injection and recombination of carriers.

[0092] The reflective film 114 covers the front end face of the structure to form a reflective interface of an optical resonant cavity, and the antireflection film 115 at the rear end face cooperates to form an asymmetric resonant cavity structure. When the laser works, the front end reflective film 114 reflects part of the light wave back to the active region to maintain lasing oscillation, while allowing a certain proportion of light wave to be transmitted and output. The material of the reflective film 114 can be a multilayer dielectric film or a metal film, which realizes high reflectivity in a specific waveband by using corresponding film layer thickness and material refractive index. The reflectivity of the reflective film 114 is 50%-100%. In some specific embodiments, the reflective film 114 can be an alternating deposition of silicon dioxide and silicon nitride dielectric layers, and the reflectivity in the target waveband can be adjusted to be more than 95%.

[0093] The antireflection film 115 reduces the reflectivity of the rear end face to suppress the feedback of the reverse light field and effectively suppress the oscillation of high-order modes. The material of the antireflection film 115 can be a single layer of magnesium fluoride or silicon dioxide film, which reduces the interface refractive index difference to reduce light reflection loss. The reflectivity of the antireflection film 115 is less than or equal to 90%. In some specific embodiments, the antireflection film 115 can be a single layer of magnesium fluoride film, and the reflectivity at the target wavelength can be controlled to be within 5%.

[0094] The present application cooperates the reflective film 114 and the antireflection film 115 to maintain the light feedback required for the main mode oscillation, and to destroy the resonance condition of the high-order mode through the asymmetric reflection characteristics. In addition, the double-electrode structure can improve the uniformity of the carrier distribution compared with the single-sided electrode layout, and avoid the local thermal effect caused by current crowding. The present application effectively suppresses the excitation of high-order modes in the laser, eliminates the ghost mode resonance phenomenon in the substrate 101, improves the concentration of the light field energy in the center region of the waveguide, and optimizes the light field distribution in the resonant cavity through the joint action of the reflective film 114 and the antireflection film 115. The mode noise and the spectral linewidth are reduced, and the current injection efficiency is enhanced through the double-electrode structure, so as to finally realize the reduction of the beam divergence angle and the regularization of the far-field spot.

[0095] Embodiment 2

[0096] The embodiment of the present application is different from the embodiment 1 in that the epitaxial structure comprises an electron supply layer 102 and a derivative layer which are stacked in sequence, the electron supply layer 102 is arranged on the substrate 101, the derivative layer has a covered area and an uncovered area on the side away from the electron supply layer 102, the filling material layer 111 is arranged on the uncovered area of the derivative layer, and the ridge waveguide structure is arranged on the covered area of the derivative layer.

[0097] The covered area is a selected area of the surface of the derivative layer for carrying the ridge waveguide structure, and the uncovered area is the remaining area of the surface of the derivative layer which is not occupied by the ridge waveguide structure.

[0098] Specifically, the electron supply layer 102 and the derivative layer form a vertical stack structure, and the surface of the derivative layer is divided into a covered area and an uncovered area. The ridge waveguide structure is prepared on the covered area to form a light field confinement core, and the local refractive index distribution is changed by embedding the filling material layer 111 in the uncovered area. When the light wave is transmitted in the ridge waveguide, the refractive index abrupt interface formed between the filling material layer 111 and the derivative layer can reflect light waves of a specific waveband, thereby forming a distributed Bragg reflection effect in the uncovered area, so that the light field energy is confined inside the ridge waveguide in the covered area, avoiding diffusion to the uncovered area.

[0099] By introducing the filling material layer 111 in the uncovered area of the derivative layer, a periodic refractive index modulation structure is formed to effectively suppress the excitation of high-order modes. At the same time, the interface reflection characteristics of the filling material layer 111 and the derivative layer can weaken the tendency of the light field to penetrate into the substrate 101, significantly improve the mode stability, effectively suppress the generation of high-order modes and ghost modes during the operation of the laser, improve the beam divergence characteristics, enhance the energy concentration degree of the light field in the ridge waveguide region, and thus improve the spatial coherence and far-field spot quality of the laser.

[0100] The embodiment of the present application also provides an optical device comprising the reflector.

[0101] The optical device can be a laser, an optical fiber communication device, and an optical filter, etc. In the embodiment, the optical device is a laser comprising the reflector.

[0102] The reflector combines the filling material layer 111 with the uncovered area of the epitaxial structure to form a high-reflection band in the target waveband, thereby limiting the concentrated distribution of the light field energy in the central area of the ridge waveguide.

[0103] When the light field diffuses outward, the high reflection characteristic of the filling material layer 111 can block the propagation of high-order modes in the non-covered area, while suppressing the leakage of light field energy to the substrate 101, so that the light field energy is limited in the covered area of the ridge waveguide, avoiding mode instability caused by spatial hole burning effect or unreasonable epitaxial structure refractive index distribution.

[0104] Compared with related technologies, the traditional laser has a large ridge waveguide width or design defects of the epitaxial structure, which causes high-order modes and ghost modes to be excited, resulting in an increase in beam divergence angle and splitting of far-field spot. The optical device of the present application actively limits the light field expansion range through the reflector, eliminates the resonance condition of high-order modes and ghost modes, thereby avoiding mode noise and power jitter, and can effectively improve the mode stability of the optical device and suppress the increase in beam divergence angle and the splitting of far-field spot.

[0105] The present application also provides a preparation method, comprising the following steps:

[0106] Referring to Figure 6 As shown in the figure, the substrate 101 is placed in the growth chamber of the MOCVD device, and the epitaxial structure of the FP laser is obtained by sequentially growing the electron supply layer 102, the N-type cladding layer 103, the N-type waveguide layer 104, the quantum well active layer 105, the P-type waveguide layer 106, the electron blocking layer 107, the P-type cladding layer 108, the hole supply layer 109, and the ohmic contact layer 110;

[0107] Referring to Figure 7 As shown in the figure, the hole supply layer 109 and the ohmic contact layer 110 are etched to form a ridge waveguide structure through photolithography and dry etching process;

[0108] Referring to Figure 8 As shown in the figure, the substrate 101 and the electron supply layer 102 are etched through photolithography and dry etching process;

[0109] Referring to Figure 9 As shown in the figure, the filling material layer 111 is grown by PECVD or magnetron sputtering process;

[0110] Referring to Figure 3 As shown in the figure, the anode electrode and the cathode electrode are made by photolithography and E-beam evaporation process;

[0111] Referring to Figure 5 As shown in the figure, a reflective film 114 with a reflection coefficient of 50%-100% is coated on the back end surface of the active area of the device by optical coating, electroplating, etc., and an anti-reflection film 115 with a reflection coefficient less than or equal to 90% is coated on the front end surface of the device.

[0112] It should be understood that many of the materials and devices exemplified in this disclosure are articles of manufacture (i.e., articles of manufacture) according to this disclosure. The articles of manufacture can be manufactured as such or can be manufactured by combining the materials and devices exemplified in this disclosure. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. It should be understood that, in some embodiments, equivalents to the specific electrode structures and / or methods described herein can be employed without departing from the scope of the application. Accordingly, the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of "including," "comprising," "having," "containing," "involving," "characterized by," "characterized into," and variations thereof herein, is meant to encompass the items listed thereafter, and equivalents thereof as well as additional items. Although the foregoing application has been described in some detail by way of illustration and example, it is not to be limited thereby, but rather, only by the scope of the appended claims.

Claims

1. A reflector, characterized by, The application relates to a reflector, comprising: a substrate (101); an epitaxial structure arranged on the substrate (101), and a side of the epitaxial structure facing away from the substrate having a covered area and an uncovered area; a ridge waveguide structure arranged on the covered area of the epitaxial structure; a filling material layer (111) arranged on the uncovered area of the epitaxial structure so that the reflector forms a high-reflection band in a target wave band; a plurality of the filling material layers (111) are arranged on the uncovered area in a spaced manner; the thickness of two adjacent filling material layers (111) is lambda / 4n, n is the refractive index of the filling material, the interval between the two adjacent filling material layers is t, t is lambda / 4m, m is the refractive index of the interval, and lambda is the target wavelength of the reflector.

2. A reflector as claimed in claim 1, characterised in that: One end of the filling material layer (111) is located on the uncovered area of the epitaxial structure, and the other end extends towards the substrate (101) and into the substrate (101).

3. A reflector according to any one of claims 1-2, characterized in that: The epitaxial structure comprises an electron supply layer (102) and a derivative layer, the electron supply layer (102) is arranged on the substrate (101), the electron supply layer (102) has a first area and a second area, the derivative layer is arranged on the first area of the electron supply layer, the second area serves as the uncovered area, and the filling material layer (111) is arranged on the second area of the electron supply layer (102); the covered area is arranged on the derivative layer, and the ridge waveguide structure is arranged on the derivative layer and located on the covered area.

4. A reflector according to any one of claims 1-2, characterized in that: The epitaxial structure comprises an electron supply layer (102) and a derivative layer arranged in sequence, the electron supply layer (102) is arranged on the substrate (101), a side of the derivative layer facing away from the electron supply layer (102) has the covered area and the uncovered area, the filling material layer (111) is arranged on the uncovered area of the derivative layer, and the ridge waveguide structure is arranged on the derivative layer and located on the covered area.

5. A reflector according to any one of claims 1-2, characterized in that: The filling material layer (111) is a low-refractive medium layer.

6. The reflector according to claim 3, wherein: the derivative layer comprises an N-type cladding layer (103), an N-type waveguide layer (104), a quantum well active layer (105), a P-type waveguide layer (106), an electron blocking layer (107) and a P-type cladding layer (108); the ridge waveguide structure is arranged on the P-type cladding layer (108); and / or the material of the N-type cladding layer (103) is AlInGaN or AlGaAs, the thickness of the N-type cladding layer (103) is greater than or equal to 0.1 mu m and less than or equal to 3 mu m; and / or the material of the N-type waveguide layer (104) is AlInGaN or AlGaAs, the thickness of the N-type waveguide layer (104) is greater than or equal to 0.1 mu m and less than or equal to 0.5 mu m. And / or, the material of the quantum well active layer (105) is AlInGaN well layer-AlInGaN barrier layer alternately grown or InGaAs well layer-AlGaAs barrier layer alternately grown, the thickness of the quantum well active layer (105) is greater than or equal to 0.02 μm and less than or equal to 0.5 μm; And / or, the material of the P-type waveguide layer (106) is AlInGaN or AlGaAs, the thickness of the P-type waveguide layer (106) is greater than or equal to 0.1 μm and less than or equal to 0.5 μm; And / or, the material of the electron blocking layer (107) is AlInGaN or AlGaAs, the thickness of the electron blocking layer (107) is greater than or equal to 0.1 μm and less than or equal to 0.3 μm; And / or, the material of the P-type cladding layer (108) is AlInGaN or AlGaAs, the thickness is greater than or equal to 0.1 μm and less than or equal to 3 μm.

7. A reflector as claimed in claim 6, characterised in that: The ridge waveguide structure comprises a hole supply layer (109) and an ohmic contact layer (110) arranged in layers, the hole supply layer (109) is located on the P-type cladding layer (108); And / or, the material of the hole supply layer (109) is AlInGaN or AlGaAs, the thickness is greater than or equal to 0.3 μm and less than or equal to 1 μm; And / or, the material of the ohmic contact layer (110) is AlInGaN or AlGaAs, the thickness is greater than or equal to 95 nm and less than or equal to 105 nm.

8. A reflector according to any one of claims 1-2, characterized in that: The front end surface of the substrate (101), the epitaxial structure and the ridge waveguide structure in the first direction is provided with a reflective film (114), the back end surface of the epitaxial structure and the ridge waveguide structure in the first direction is provided with an anti-reflection film (115), the ridge waveguide structure is provided with a first electrode (112), the bottom of the substrate (101) is provided with a second electrode (113); And / or, the material of the first electrode (112) is Cr / Au, Ti / Au or Ni / Au; And / or, the material of the second electrode (113) is Cr / Au, Ti / Au or Ni / Au; And / or, the reflectivity of the reflective film (114) is 50%-100%; And / or, the reflectivity of the anti-reflection film (115) is less than or equal to 90%.

9. An optical device, characterized by The reflector comprises the reflector according to any one of claims 1-8.

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