DFB laser based on top metal grating

Abstract

The invention relates to the technical field of semiconductor lasers, in particular to a DFB laser based on a top metal grating, and the DFB laser comprises a gain chip, the left end face of the gain chip is plated with a high-reflection HR film, and the right end face of the gain chip is plated with an anti-reflection AR film; the upper end face of the gain chip is provided with a ridge optical waveguide, and the upper end face of the ridge optical waveguide is provided with a metal Bragg reflection grating layer. A self-heterodyne interference method (the line width of a local oscillator is smaller than 500 Hz) is adopted, and the measured value of the 3dB line width is 50 Hz (the measured value of a traditional DFB is 125 kHz). The mode purity degree is verified through a Lorenzian fitting broadening factor 1.15; the wavelength drift is less than 0.05 pm / DEG C within the range of-40 DEG C to 85 DEG C after compensation of the temperature compensation circuit. The temperature tuning coefficient is 0.08 pm / DEG C, the current tuning coefficient is 0.05 pm / mA, and the tuning coverage range is 1530-1545 nm.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor lasers, and specifically to a DFB laser based on a top metal grating. Background Art

[0002] A traditional DFB laser (distributed feedback laser) is a single-mode laser device based on semiconductor materials. Its core feature is the integration of a Bragg grating structure near the active layer. This grating forms a distributed feedback mechanism through periodic refractive index changes, allowing only specific wavelengths that satisfy the Bragg condition to achieve stimulated emission, thereby suppressing multi-longitudinal mode oscillation and achieving high-purity single-mode output.

[0003] Traditional DFB lasers have problems such as complex processes, low yield, high cost, and low grating reflectivity, which limit their applications in the fields with high-performance light source requirements. Summary of the Invention

[0004] The present invention provides a DFB laser based on a top metal grating to solve the problems raised in the above background art.

[0005] To achieve the above object, the present invention provides the following technical solution. A DFB laser based on a top metal grating includes: a gain chip, a high-reflection HR film is plated on the left end face of the gain chip, and an anti-reflection AR film is plated on the right end face of the gain chip.

[0006] A ridge optical waveguide is provided on the upper end face of the gain chip, and a metal Bragg reflection grating layer is provided on the upper end face of the ridge optical waveguide.

[0007] As a preference of the above technical solution, the gain chip adopts an InP / InGaAsP quantum well structure, and the central emission wavelength λ ranges from 1530 to 1610 nm.

[0008] Further, the gain chip adopts an InP / InGaAsP quantum well structure, and the central emission wavelength λ is 1550 nm.

[0009] As a preference of the above technical solution, the thickness of the high-reflection HR film is λ / 2, and the reflectivity R1 > 99.9%; the thickness of the anti-reflection AR film is λ / 4, and the reflectivity R2 < 0.03%.

[0010] As a preference of the above technical solution, the length of the ridge optical waveguide is 1500 μm, the ridge width is 3 - 5 μm, and the ridge height is 2 - 4 μm.

[0011] Further, the length of the ridge optical waveguide is 1500 μm, the ridge width is 4 μm, and the ridge height is 3 μm.

[0012] As an optimization of the above technical solution, the preparation process of the metal Bragg reflection grating layer is specifically: formed by electron beam lithography and ICP etching.

[0013] As an optimization of the above technical solution, the metal Bragg reflection grating layer is a Cr / Au double-layer structure with a thickness of 150 - 250 nm.

[0014] Furthermore, the metal Bragg reflection grating layer is a Cr / Au double-layer structure with a thickness of 200 nm.

[0015] As an optimization of the above technical solution, the grating constant of the metal Bragg reflection grating layer is λ / 2.

[0016] The present invention provides a DFB laser based on a top metal grating, having the following beneficial effects: 1. Structural innovation: The top metal Bragg reflection grating layer is used to replace the traditional sandwich semiconductor grating, simplifying the process and reducing costs.

[0017] 2. Performance improvement: The top metal Bragg reflection grating layer can improve the reflection efficiency, narrow the linewidth, and reduce the threshold current; through performance testing, using the self-heterodyne interference method (local oscillator linewidth < 500 Hz), the measured value of the 3dB linewidth is 50 Hz (125 kHz for traditional DFB); the mode purity is verified by the Lorenzian fitting broadening factor of 1.15; in the range of -40°C to 85°C, after temperature compensation by the temperature compensation circuit, the wavelength drift < 0.05 pm / °C. The temperature tuning coefficient is 0.08 pm / °C, the current tuning coefficient is 0.05 pm / mA, and the tuning coverage range is 1530 - 1545 nm. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is a schematic structural diagram of the present invention; Figure 2 is Figure 1 the left view of Figure 3 is Figure 1 the top view of

[0019] In the figure: 1. Gain chip; 2. High reflection HR film; 3. Anti-reflection AR film; 4. Ridge optical waveguide; 5. Metal Bragg reflection grating layer. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0020] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0021] Embodiment 1 As Figures 1 - 3As shown in the figure, in this embodiment, a DFB laser based on a top metal grating includes: a gain chip 1, a high-reflection HR film 2 is plated on the left end face of the gain chip 1, and an anti-reflection AR film 3 is plated on the right end face of the gain chip 1.

[0022] In specific implementation, the gain chip 1 adopts an InP / InGaAsP quantum well structure, and the central emission wavelength λ ranges from 1530 nm; the thickness of the high-reflection HR film 2 is λ / 2, and the reflectivity R1 > 99.9%; the thickness of the anti-reflection AR film 3 is λ / 4, and the reflectivity R2 < 0.03%.

[0023] A ridge optical waveguide 4 is arranged on the upper end face of the gain chip 1, and a metal Bragg reflection grating layer 5 is arranged on the upper end face of the ridge optical waveguide 4.

[0024] In specific implementation, the length of the ridge optical waveguide 4 is 1500 μm, the ridge width is 3 μm, and the ridge height is 2 μm.

[0025] The preparation process of the metal Bragg reflection grating layer 5 is specifically: formed by electron beam lithography and ICP etching.

[0026] The metal Bragg reflection grating layer 5 is a Cr / Au double-layer structure with a thickness of 150 nm.

[0027] The grating constant of the metal Bragg reflection grating layer 5 is λ / 2.

[0028] Embodiment 2 As Figures 1 - 3 As shown in the figure, in this embodiment, a DFB laser based on a top metal grating includes: a gain chip 1, a high-reflection HR film 2 is plated on the left end face of the gain chip 1, and an anti-reflection AR film 3 is plated on the right end face of the gain chip 1.

[0029] In specific implementation, the gain chip 1 adopts an InP / InGaAsP quantum well structure, and the central emission wavelength λ ranges from 1610 nm; the thickness of the high-reflection HR film 2 is λ / 2, and the reflectivity R1 > 99.9%; the thickness of the anti-reflection AR film 3 is λ / 4, and the reflectivity R2 < 0.03%.

[0030] A ridge optical waveguide 4 is arranged on the upper end face of the gain chip 1, and a metal Bragg reflection grating layer 5 is arranged on the upper end face of the ridge optical waveguide 4.

[0031] In specific implementation, the length of the ridge optical waveguide 4 is 1500 μm, the ridge width is 5 μm, and the ridge height is 4 μm.

[0032] The preparation process of the metal Bragg reflection grating layer 5 is specifically: formed by electron beam lithography and ICP etching.

[0033] The metal Bragg reflection grating layer 5 is a Cr / Au double-layer structure with a thickness of 250 nm.

[0034] The grating constant of the metal Bragg reflection grating layer 5 is λ / 2.

[0035] Example 3 As Figures 1 - 3 shown, in this example, a DFB laser based on a top metal grating includes: a gain chip 1, a high-reflection HR film 2 is plated on the left end face of the gain chip 1, and an anti-reflection AR film 3 is plated on the right end face of the gain chip 1.

[0036] In specific implementation, the gain chip 1 adopts an InP / InGaAsP quantum well structure, and the central emission wavelength λ ranges from 1550 nm; the thickness of the high-reflection HR film 2 is λ / 2, and the reflectivity R1 > 99.9%; the thickness of the anti-reflection AR film 3 is λ / 4, and the reflectivity R2 < 0.03%.

[0037] A ridge optical waveguide 4 is arranged on the upper end face of the gain chip 1, and a metal Bragg reflection grating layer 5 is arranged on the upper end face of the ridge optical waveguide 4.

[0038] In specific implementation, the length of the ridge optical waveguide 4 is 1500 μm, the ridge width is 4 μm, and the ridge height is 3 μm.

[0039] The preparation process of the metal Bragg reflection grating layer 5 is specifically: formed by electron beam lithography and ICP etching.

[0040] The metal Bragg reflection grating layer 5 is a Cr / Au double-layer structure with a thickness of 200 nm.

[0041] The grating constant of the metal Bragg reflection grating layer 5 is λ / 2.

[0042] Performance tests were carried out on the three types of lasers provided in Examples 1 - 3, and the results are as follows: 1. Linewidth measurement: Using the self-heterodyne interferometry method (local oscillator linewidth < 500 Hz), the measured value of the 3 dB linewidth is 50 Hz (125 kHz for traditional DFB). The mode purity was verified by the Lorenzian fitting broadening factor of 1.15.

[0043] 2. Wavelength stability: In the range of -40°C to 85°C, after compensation by the temperature compensation circuit, the wavelength drift < 0.05 pm / °C. The temperature tuning coefficient is 0.08 pm / °C, the current tuning coefficient is 0.05 pm / mA, and the tuning coverage range is 1530 - 1545 nm.

[0044] Although embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A DFB laser based on a top metal grating, comprising a gain chip (1), characterized in that: The left end face of the gain chip (1) is coated with a high-reflection HR film (2), and the right end face of the gain chip (1) is coated with an anti-reflection AR film (3). The upper end face of the gain chip (1) is provided with a ridge optical waveguide (4), and the upper end face of the ridge optical waveguide (4) is provided with a metal Bragg reflection grating layer (5).

2. The DFB laser based on a top metal grating according to claim 1, wherein: The gain chip (1) adopts an InP / InGaAsP quantum well structure, and the range of the central emission wavelength λ is 1530 - 1610 nm.

3. The DFB laser based on a top metal grating according to claim 2, characterized in that: The gain chip (1) adopts an InP / InGaAsP quantum well structure, and the central emission wavelength λ is 1550 nm.

4. The DFB laser based on a top metal grating according to claim 3, characterized in that: The thickness of the high-reflection HR film (2) is λ / 2, and the reflectivity R1 > 99.9%; the thickness of the anti-reflection AR film (3) is λ / 4, and the reflectivity R2 < 0.03%.

5. The DFB laser based on a top metal grating according to claim 3, characterized in that: The grating constant of the metal Bragg reflection grating layer (5) is λ / 2.

6. The DFB laser based on a top metal grating according to claim 1, wherein: The length of the ridge optical waveguide (4) is 1500 μm, the ridge width is 3 - 5 μm, and the ridge height is 2 - 4 μm.

7. The DFB laser based on a top metal grating according to claim 6, wherein: The length of the ridge optical waveguide (4) is 1500 μm, the ridge width is 4 μm, and the ridge height is 3 μm.

8. A DFB laser based on a top metal grating according to claim 1, characterized in that, The preparation process of the metal Bragg reflection grating layer (5) is specifically: formed by electron beam lithography and ICP etching.

9. A DFB laser based on a top metal grating according to claim 1, characterized in that: The metal Bragg reflection grating layer (5) is a Cr / Au double-layer structure with a thickness of 150 - 250 nm.

10. A DFB laser based on a top metal grating according to claim 9, characterized in that: The metal Bragg reflection grating layer (5) is a Cr / Au double-layer structure with a thickness of 200 nm.

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