Distributed feedback laser integrated with heater for adjusting HR end surface phase and manufacturing method

Abstract

The invention discloses a distributed feedback laser integrated with a heater for adjusting the HR end face phase and a manufacturing method, and belongs to the technical field of photoelectron, the front end face and the rear end face of the distributed feedback laser are an AR end face and an HR end face respectively, and an AR film system and an HR film system are arranged on the front end face and the rear end face respectively so as to increase the output power of the front end face; a heater for adjusting the phase of the HR end face is integrated on one side, close to the HR end face, of the distributed feedback laser. The adjustability of the phase of the HR end surface can improve the single-mode yield and wavelength accuracy of the distributed feedback laser.

Description

Technical Field

[0001] The present invention belongs to the field of optoelectronic technology and relates to a distributed feedback laser, in particular to a distributed feedback laser with an integrated heater for adjusting the HR facet phase and a manufacturing method thereof. Background Art

[0002] Distributed feedback (DFB) lasers are widely used in high-precision optical communications, fiber optic sensing, and spectral analysis due to their excellent single-mode characteristics and high-frequency stability. In optical communications, DFB lasers are usually used as the core light source of wavelength division multiplexing (WDM) systems. Their wavelength stability and single-mode performance directly affect the transmission rate and signal quality of the system. In the field of fiber optic sensing, DFB lasers have become an important laser source for distributed temperature and strain sensing due to their narrow linewidth and high spectral stability. However, during the manufacturing process of DFB lasers, the cleavage position of the HR end face is random, which easily introduces uncertain phase differences, thereby reducing the single-mode yield and wavelength accuracy of the laser.

[0003] In recent years, researchers have proposed some improvement measures to improve the wavelength accuracy and single-mode yield of DFB lasers. For example, a π phase shift at the center of the grating is introduced into the laser design to enhance the single-mode performance, or precise wavelength selection is achieved by optimizing the grating period. However, these methods have limited effectiveness in dealing with the phase randomness of the HR end facet. In addition, some studies have attempted to use external heaters or electro-optical modulators to dynamically adjust the wavelength of the laser, but since these devices usually require additional integration and optical path design, the manufacturing process is complicated and the cost is increased. Therefore, how to effectively solve the problem of HR end facet phase randomness and improve the single-mode yield and wavelength accuracy of DFB lasers has become one of the key bottlenecks in the current development of high-performance laser technology. Summary of the Invention

[0004] The present invention provides a distributed feedback laser with an integrated heater for adjusting the HR end facet phase and a manufacturing method thereof, so as to overcome the defects of the prior art.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] In its first aspect, the present invention provides a distributed feedback laser (DFG) with an integrated heater to adjust the HR facet phase. The front and rear facets of the DFG laser are the AR facet and the HR facet, respectively, and are equipped with AR (low reflectivity) and HR (high reflectivity) film systems, respectively, to increase the output power of the front facet. A heater for adjusting the HR facet phase is integrated on the side of the DFG laser closest to the HR facet. The controllability of the HR facet phase can improve the single-mode yield and wavelength accuracy of the DFG laser.

[0007] Furthermore, the distributed feedback laser is a ridge waveguide laser with a ridge structure; and the heater is integrated on any one side or both sides of the ridge structure.

[0008] Furthermore, the heater is made of Ti and Pt and is provided with electrodes for injecting current, and the HR end face phase is adjusted by changing the injected current.

[0009] Furthermore, the heater is stacked with a Ti layer and a Pt layer in sequence from bottom to top; the thickness of the Ti layer is 30 to 70 nm, preferably 50 nm; the thickness of the Pt layer is 200 to 300 nm, preferably 250 nm.

[0010] Furthermore, the electrode is Ti, Pt or Au.

[0011] Furthermore, the distributed feedback laser is stacked with a substrate, a buffer layer, a lower confinement layer, a multi-quantum well layer, an upper confinement layer, a grating layer, a waveguide layer and a contact layer from bottom to top, and the waveguide layer and the contact layer form a ridge structure; the heater is integrated on the grating layer.

[0012] Furthermore, the grating layer is fabricated using a reconstruction equivalent chirp technique: a uniformly periodic grating sampling structure is created within each laser unit through a single holographic exposure and a single holographic lithography process. The distributed feedback laser utilizes this technique to select the lasing wavelength. Specifically, the sampled grating uses the +1 order of the grating as the primary mode to select the lasing wavelength, and the sampling period of the holographic lithography is varied to select the lasing wavelength for each laser unit.

[0013] In a second aspect, the present invention also provides a method for manufacturing the above-mentioned distributed feedback laser with an integrated heater to adjust the HR end face phase, comprising the following steps: S1, manufacturing a distributed feedback laser; S2, sputtering an AR film system and a HR film system on the AR end face and the HR end face of the distributed feedback laser respectively; S3, manufacturing a heater on the side of the distributed feedback laser close to the HR end face.

[0014] Furthermore, the S1 includes the following steps: S1.1, sequentially growing a buffer layer, a lower confinement layer, a multi-quantum well layer, and an upper confinement layer on the upper surface of the substrate by metal organic compound vapor deposition; S1.2, producing a grating layer with different sampling periods by one ultraviolet lithography and one holographic lithography; S1.3, depositing InP above the grating layer to bury the grating layer, and then sequentially growing a waveguide layer and a contact layer; S1.4, corroding the waveguide layer and the contact layer to form a ridge shape, and growing a front metal electrode in the ridge shape area above the contact layer; S1.5, thinning and polishing the back side of the laser array substrate, evaporating the back electrode and heating it to obtain an alloy, and obtaining the distributed feedback laser after chip cleavage.

[0015] Furthermore, the specific method of S3 is: magnetron sputtering Ti layer and Pt layer from bottom to top on the side of the distributed feedback laser close to the HR end face to form a heater with two powered ports; then sputtering Ti, Pt or Au as electrodes on the two powered ports for powering the heater to generate heat.

[0016] The beneficial effects of the present invention are as follows: the present invention provides a distributed feedback laser and a manufacturing method with an integrated heater to adjust the HR end face phase, a sampling grating is made by reconstructing the equivalent chirp technology to select the lasing wavelength, and AR film systems and HR film systems are sputtered on the front and rear end faces of the distributed feedback laser respectively to improve the output power and laser performance. In order to overcome the problems caused by the randomness of the HR end face phase, a Ti-Pt metal heater is integrated on the HR end face, and the phase of the HR end face is adjusted by changing the injection current of the heater, thereby effectively improving the single-mode yield and wavelength accuracy of the laser. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a schematic structural diagram of a distributed feedback laser with an integrated heater for adjusting the HR facet phase of the present invention;

[0018] Figure 2 This is a schematic diagram of the wavelength change and threshold gain difference under different phases of the simulated HR end face;

[0019] Figure 3 This is a schematic diagram of the HR end face phase change at different powers of the Ti-Pt heater;

[0020] Figure 4 This is a schematic diagram of the laser spectrum at different currents of the Ti-Pt heater;

[0021] In the figure, MM is the main mold, SM1 is the side mold 1, and SM2 is the side mold 2. DETAILED DESCRIPTION

[0022] The specific embodiments of the present invention are described below with reference to the accompanying drawings.

[0023] like Figure 1As shown, the present invention provides a distributed feedback laser with an integrated heater to adjust the HR facet phase. The laser structure comprises, from bottom to top, a substrate, a buffer layer, a lower confinement layer, a multi-quantum well layer, an upper confinement layer, a grating layer, a waveguide layer, and a contact layer. The grating layer is fabricated using a reconstruction equivalent chirp technique: a sampling structure with a uniform grating period is produced in each laser unit through a single holographic exposure and a single holographic lithography process. The sampled grating uses the +1 order of the grating as the primary mode to select the lasing wavelength. The sampling period of the holographic lithography is varied to select the lasing wavelength for each laser unit. AR and HR films are sputtered on the front and rear facets of the laser, respectively, to increase the output power of the front facet. However, the randomness of the HR facet phase reduces single-mode yield and wavelength accuracy. Therefore, a heater is integrated near the HR facet to adjust the HR facet phase. The heater is composed of Ti-Pt metal. The HR facet phase is adjusted by adjusting the injection current of the Ti-Pt metal heater. The controllability of the HR facet phase can improve the single-mode yield and wavelength accuracy of the laser.

[0024] Specifically, the heater is stacked with Ti and Pt layers from bottom to top. The Ti layer has a thickness of 30 to 70 nm, preferably 50 nm; the Pt layer has a thickness of 200 to 300 nm, preferably 250 nm. The heater also has electrodes for injecting current, which are made of Ti, Pt, or Au.

[0025] Ti-Pt heaters can be applied to any type of distributed feedback lasers, including parallel, series, and matrix distributed feedback lasers.

[0026] The grating layer of each laser unit in the laser array is designed and manufactured by reconstructing the equivalent chirp technology, as follows:

[0027] First, a single UV exposure is performed to create a uniform grating with a grating period of Λ0. Holographic lithography is then used to sample the uniform grating. The +1 order of the grating is used as the primary lasing mode, and an equivalent π phase shift is introduced in each laser unit to achieve stable single-mode characteristics. The +1 order grating period of the laser is determined by the uniform grating period and the sampling period, as shown in the following formula.

[0028]

[0029] Where, Λ +1 represents the +1-order grating period after holographic lithography, Λ0 represents the uniform grating period defined by UV lithography, and p represents the sampling period of the grating.

[0030] The manufacturing method of a distributed feedback laser with an integrated heater to adjust the HR end facet phase includes the following steps:

[0031] S1.1. Growing a buffer layer, a lower confinement layer, a multi-quantum well layer, and an upper confinement layer in sequence on the upper surface of the substrate by metal organic compound vapor deposition;

[0032] S1.2, fabricating grating layers with different sampling periods by one ultraviolet lithography and one holographic lithography;

[0033] S1.3. Deposit InP on the grating layer to bury the grating layer, and then grow the waveguide layer and contact layer in sequence;

[0034] S1.4. Etching the waveguide layer and the contact layer to form a ridge, and growing a front metal electrode in the ridge region above the contact layer;

[0035] S1.5, thinning and polishing the back side of the laser array substrate, evaporating the back electrode and heating it to obtain an alloy, and cleaving the chip to obtain the distributed feedback laser;

[0036] S2, sputtering AR film system and HR film system on the front and rear end faces of the distributed feedback laser after cleavage respectively;

[0037] S3. On the side of the distributed feedback laser close to the HR end face, Ti and Pt layers are magnetron sputtered in sequence from bottom to top to form a heater with two powered ports; Ti, Pt or Au is then sputtered at the two powered ports as electrodes for powering the heater to generate heat.

[0038] Figure 2 This is a schematic diagram of the wavelength change and threshold gain difference under different phases of the simulated HR end face. Figure 2 It can be seen that under ideal conditions, controlling the phase of the laser HR facet allows for precise wavelength control and a large threshold gain difference. The magnitude of this threshold gain difference affects the laser's single-mode yield. When the facet phase is π, the laser wavelength corresponds to the Bragg wavelength (precise wavelength control) and the threshold gain difference is maximized (optimal single-mode yield).

[0039] Figure 3 This is a schematic diagram of the HR end face phase change under different powers of the Ti-Pt heater. Figure 3 It can be seen that by injecting different powers into the heater, the HR facet phase can be periodically controlled. By controlling the power of the heater, the wavelength and single-mode characteristics of the laser can be precisely controlled.

[0040] Figure 4 This is a schematic diagram of the laser spectrum under different currents of the Ti-Pt heater. Figure 4The laser spectrum changes under different heater currents. As the current increases, the laser wavelength gradually increases within a current cycle. This corresponds to the simulation results, which show that the phase of the laser facet gradually changes from 0 to 2π as the heater current changes. When the laser current is adjusted to the π phase, the wavelength is the set wavelength.

[0041] In the present invention, unless otherwise specified, the scientific and technical terms used herein have the meanings commonly understood by those skilled in the art. In addition, the materials and operating procedures used herein are those widely used in the relevant fields and conventional procedures.

[0042] It should be noted that the terms such as "upper", "lower", "left", "right", "front", "back", etc. cited in the invention are only for the convenience of description and are not used to limit the scope of implementation of the present invention. Changes or adjustments to their relative relationships should be regarded as the scope of implementation of the present invention without substantially changing the technical content.

[0043] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art will be able to modify the technical solutions described in the aforementioned embodiments or substitute equivalents for some of the technical features. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A distributed feedback laser with an integrated heater to adjust the HR facet phase, characterized by: The front and rear end faces of the distributed feedback laser are AR end face and HR end face, respectively, which are provided with AR film system and HR film system respectively; the side of the distributed feedback laser close to the HR end face is integrated with a heater for adjusting the phase of the HR end face.

2. The distributed feedback laser with integrated heater to adjust HR facet phase according to claim 1, characterized in that: The distributed feedback laser is a ridge waveguide laser with a ridge structure; The heater is integrated on either side or both sides of the ridge structure.

3. The distributed feedback laser with integrated heater to adjust HR facet phase according to claim 1, characterized in that: The heater is made of Ti and Pt and is provided with electrodes for injecting current. The HR end face phase is adjusted by changing the injected current.

4. The distributed feedback laser with integrated heater to adjust HR facet phase according to claim 3, characterized in that: The heater is stacked with a Ti layer and a Pt layer in sequence from bottom to top; The thickness of the Ti layer is 30-70 nm; the thickness of the Pt layer is 200-300 nm.

5. The distributed feedback laser with integrated heater to adjust HR facet phase according to claim 3, characterized in that: The electrode is Ti, Pt or Au.

6. The distributed feedback laser with integrated heater to adjust HR facet phase according to claim 1, characterized in that: The distributed feedback laser is stacked with a substrate, a buffer layer, a lower confinement layer, a multi-quantum well layer, an upper confinement layer, a grating layer, a waveguide layer and a contact layer from bottom to top; The heater is integrated on the grating layer.

7. The distributed feedback laser with integrated heater to adjust HR facet phase according to claim 6, characterized in that: The grating layer is manufactured by adopting the reconstruction equivalent chirp technology: a sampling structure with uniform grating period is manufactured by one holographic exposure and one holographic lithography.

8. The method for manufacturing a distributed feedback laser with an integrated heater to adjust the HR facet phase according to any one of claims 1 to 7, characterized in that: The following steps are involved: S1. Manufacturing distributed feedback laser; S2, sputtering AR film system and HR film system on the AR end face and HR end face of the distributed feedback laser respectively; S3. A heater is manufactured on the side of the distributed feedback laser close to the HR end face.

9. The method for manufacturing a distributed feedback laser with an integrated heater to adjust the HR facet phase according to claim 8, characterized in that: Said S1 comprises the following steps: S1.

1. Growing a buffer layer, a lower confinement layer, a multi-quantum well layer, and an upper confinement layer in sequence on the upper surface of the substrate by metal organic compound vapor deposition; S1.2, fabricating grating layers with different sampling periods by one ultraviolet lithography and one holographic lithography; S1.

3. Deposit InP on the grating layer to bury the grating layer, and then grow the waveguide layer and contact layer in sequence; S1.

4. Etching the waveguide layer and the contact layer to form a ridge, and growing a front metal electrode in the ridge region above the contact layer; S1.

5. Thin and polish the back side of the laser array substrate, evaporate the back side electrode and heat it to obtain an alloy, and cleave the chip to obtain the distributed feedback laser.

10. The method for manufacturing a distributed feedback laser with an integrated heater to adjust the HR facet phase according to claim 8, characterized in that: The specific method of S3 is: magnetron sputtering Ti and Pt layers from bottom to top on one side of the distributed feedback laser close to the HR end face to form a heater with two powered ports; then sputtering Ti, Pt or Au as electrodes at the two powered ports for powering the heater to generate heat.

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