A multi-period DBR superluminescent diode structure with an ultra-wide spectral width

Abstract

The application discloses a multi-period DBR super-radiation light-emitting diode structure with an ultra-wide spectrum width, wherein the upper surface of a P face electrode is divided into four areas, which are a light-emitting end ridge, an active multi-mode interference device, a plurality of non-light-emitting end ridges, a plurality of ridges with different period DBRs and an optical absorption area. The application effectively clamps the gain center wavelength through the multi-DBR structure, so that the center wavelength of the light emitted by the device is different, and then the problem that the spectrum is narrowed due to the fact that the photons close to the center gain wavelength are amplified more and the photons far away from the center gain wavelength are amplified less when the current is increased is effectively suppressed, so that the spectrum width of the device is effectively widened. The tilted ridge structure is adopted, the wide-spectrum antireflection film with a reflectivity less than 2% is deposited on the front and rear cavity surfaces, and the optical absorption area is formed on the non-light-emitting end of the device, so that the F-P oscillation is effectively suppressed through the above three methods, and the emitted light is ensured to be super-radiation light.

Description

Technical fields:

[0001] This invention relates to the field of superluminescent diode technology, and in particular to a multi-period DBR superluminescent diode structure with an ultra-wide spectral width. Background technology:

[0002] Superluminescent diodes (SLEDs) are semiconductor light-emitting devices developed in recent years. Their luminescence characteristics fall between those of lasers (LDs) and LEDs. Compared to semiconductor LEDs, SLEDs offer higher power output and a narrower divergence angle; compared to semiconductor lasers, they have a wider spectral width and a shorter coherence length. High optical power improves system accuracy and sensitivity, while a wide spectral width reduces coherence errors caused by Rayleigh scattering and the Kerr effect in optical fibers. Therefore, SLEDs are ideal light sources for fiber optic gyroscopes. Their emergence and development are largely driven by fiber optic gyroscopes, making them an important light source. Currently, SLEDs are also widely used in wavelength division multiplexing (WDM), optical coherence tomography (OCT), and tunable external cavity lasers. Most current applications require SLEDs to have both high output power and the widest possible spectral width.

[0003] Currently, the development of superluminescent light-emitting diodes (SLDs) primarily involves modifying the traditional laser structure to disrupt the optical oscillations between the front and rear cavity surfaces of the Fabry-Perot (FP) type, thereby suppressing photolasing. This mainly includes three methods: 1. Introducing a non-pump absorption region behind the SLD cavity surface; 2. Depositing an antireflection coating on the device's end faces; 3. Using tilted end faces. Although optical oscillations are suppressed, the FP cavity remains. With increasing current, photons closer to the center gain wavelength receive greater amplification, while photons farther from the center gain wavelength receive less amplification, thus narrowing the spectrum. When the driving current increases to a certain extent, or when partial aging is suppressed, the device undergoes lasing, spontaneous superluminescence is replaced by lasing, and the device fails.

[0004] Chinese patent CN109037403A, "Structure of Superluminescent Diode with Transparent Window", discloses a structure of superluminescent diode with a transparent window. It improves the luminous efficiency of the die by using a mask waveguide structure. At the same time, it uses a waveguide absorption region + transparent window and evaporation antireflection film to reduce the residual reflectivity of the cavity surface and improve the optical power. However, the patent does not provide how to increase the spectral width of the superluminescent diode.

[0005] Chinese patent CN210245533U, "Multi-Quantum Well Structures of Different Widths for Broadening the Spectral Width of Superluminescent Diodes," discloses a method for broadening the spectral width by growing quantum wells of different thicknesses to change the center gain wavelength, thereby achieving the purpose of broadening the spectral width. However, this method requires the growth of multi-layer quantum well structures, which leads to an increase in device voltage and a decrease in efficiency. Furthermore, under high current injection conditions, the center wavelength of this method tends to be consistent due to mode competition, thus narrowing the spectral width. Summary of the Invention:

[0006] The purpose of this invention is to provide a multi-period DBR superluminescent diode structure with an ultra-wide spectral width to overcome the shortcomings of the prior art.

[0007] The present invention is implemented by the following technical solution: a multi-period DBR superluminescent diode structure with ultra-wide spectral width, comprising, from top to bottom, a P-side electrode, a P-type confinement layer, a P-type waveguide layer, an active layer, an N-type waveguide layer, an N-type confinement layer, an InP substrate, and an N-side electrode; the upper surface of the P-side electrode is divided into four regions, namely, a light-emitting end ridge, an active multimode interferometer, multiple non-light-emitting end ridges, multiple ridges with DBRs of different periods, and an optical absorption region.

[0008] Furthermore, the etching depth of the light-emitting end ridge and the multiple non-light-emitting end ridges is between 0.5 and 1.5 μm.

[0009] Furthermore, the light-emitting end ridge and the DBR ridge with different periods are all inclined ridges, forming an angle of 3 to 8° with the light-emitting direction.

[0010] Furthermore, the light-emitting end ridge is an inclined ridge that is narrower at the front and wider at the back. The width of the light-emitting end ridge that contacts the active multimode interferometer is 6-10 μm, and the width of the light-emitting end ridge that contacts the light-emitting cavity surface is 3-5 μm.

[0011] Furthermore, the active multimode interferometer has a parallelogram structure with a side length of 20–50 μm.

[0012] Furthermore, the width of the DBR ridges with different periods is 2–4 μm.

[0013] Furthermore, the area of ​​the optical absorption region accounts for 3% to 10% of the area of ​​the upper surface of the P-side electrode.

[0014] Advantages of this invention:

[0015] This invention effectively clamps the gain center wavelength using a multi-DBR structure, resulting in different center wavelengths of the emitted light. This effectively suppresses the problem of photons closer to the center gain wavelength receiving greater amplification and photons farther from the center gain wavelength receiving less amplification when the current increases, thus narrowing the spectrum. Ultimately, this effectively broadens the spectral width of the device. By employing a tilted ridge structure, depositing a broadband antireflection film with a reflectivity of less than 2% on both the front and rear cavity surfaces, and creating an optical absorption region at the non-emitting end of the device, these three methods effectively suppress FP oscillations, ensuring that the emitted light is superradiative. Attached image description:

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a top view of the P-side of a multi-period DBR superluminescent diode structure with an ultra-wide spectral width, according to an embodiment of the present invention. Detailed implementation method:

[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] This invention provides a multi-period DBR superluminescent diode structure with an ultra-wide spectral width. The multi-period DBR superluminescent diode is a P-side structure of a superluminescent diode, which includes, from top to bottom, a P-side electrode, a P-type confinement layer, a P-type waveguide layer, an active layer, an N-type waveguide layer, an N-type confinement layer, an InP substrate, and an N-side electrode. The active layer includes several quantum well layers of different thicknesses, and a barrier layer is disposed between each quantum well layer.

[0020] like Figure 1 As shown, the upper surface of the P-side electrode is divided into four regions: the light-emitting ridge 1, the active multimode interferometer 2, multiple non-light-emitting ridges 3, multiple ridges with different periodic DBRs 4, and the optical absorption region 5. Figure 1As shown, the multiple non-emitting end ridges 3 in this embodiment include non-emitting end ridge 1 3-1, non-emitting end ridge 2 3-2, non-emitting end ridge 3-3, and non-emitting end ridge 4 3-4. The multiple ridges 4 with DBRs of different periods include DBR 1 4-1, DBR 2 4-2, DBR 3 4-3, and DBR 4-4.

[0021] The etching depth of the light-emitting ridge 1 and the multiple non-light-emitting ridges 3 is between 0.5 and 1.5 μm. The light-emitting ridge 1 and the DBR ridges 4 with different periods are all inclined ridges, forming an angle of 3 to 8° with the light-emitting direction 6. The inclination angle of the ridges is 3 to 8°. If the inclination is too large, it will lead to difficulties in optical path design, and if it is too small, it will weaken the function of eliminating FP lasing.

[0022] To better extract light from the active multimode interferometer, the light-emitting ridge 1 is an inclined ridge that is narrow at the front and wide at the back. The width of the light-emitting ridge 1 that contacts the active multimode interferometer 2 is 6-10 μm, and the width of the light-emitting ridge 1 that contacts the light-emitting cavity surface is 3-5 μm.

[0023] The active multimode interferometer 2 has a parallelogram structure with a side length of 20–50 μm; the width of the DBR ridges 4 with different periods is 2–4 μm; the area of ​​the optical absorption region 5 accounts for 3%–10% of the area of ​​the upper surface of the P-side electrode.

[0024] This multi-periodic DBR structure, which broadens the spectral width of superluminescent diodes, is a structure of superluminescent diodes. From the light-emitting cavity surface to the non-light-emitting cavity surface, there are multi-periodic DBR regions, active multimode interference regions, and tilted waveguide output regions, respectively.

[0025] A broadband antireflection film is deposited on the front and rear cavity surfaces of the ridge strip. The reflectivity of the broadband antireflection film is less than 2%, the center wavelength of the broadband antireflection film is located at 1550 nm, and the spectral width of the broadband antireflection film is greater than 80 nm. The antireflection film increases transmission and reduces the probability of reflection, further suppressing FP lasing on the front and rear cavity surfaces. Together with the aforementioned tilted ridge strip and optical absorption region, it suppresses FP lasing and effectively solves the constraint relationship between the output power and the output spectral width of the superluminescent diode.

[0026] The working principle of this invention is as follows: By using a multi-DBR structure to effectively clamp the gain center wavelength, the center wavelength of the emitted light from the device varies. This effectively suppresses the problem of photons closer to the center gain wavelength receiving greater amplification and photons farther from the center gain wavelength receiving less amplification when the current increases, thus narrowing the spectrum. Ultimately, this effectively broadens the spectral width of the device. The invention employs a tilted ridge structure, deposits a broadband antireflection film with a reflectivity of less than 2% on both the front and rear cavity surfaces, and creates an optical absorption region at the non-emitting end of the device. These three methods effectively suppress FP oscillations, ensuring that the emitted light is superradiative.

[0027] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A multi-period DBR superluminescent diode structure with an ultra-wide spectral width, characterized in that, It includes, from top to bottom, a P-side electrode, a P-type confinement layer, a P-type waveguide layer, an active layer, an N-type waveguide layer, an N-type confinement layer, an InP substrate, and an N-side electrode; the upper surface of the P-side electrode is divided into four regions, namely, a light-emitting end ridge (1), an active multimode interferometer (2), multiple non-light-emitting end ridges (3), multiple ridges with different periodic DBRs (4), and an optical absorption region (5); The etching depth of the light-emitting end ridge (1) and the multiple non-light-emitting end ridges (3) is between 0.5 and 1.5 μm; The light-emitting end ridge (1) and the DBR ridge (4) with different periods are both inclined ridges, forming an angle of 3~8° with the light-emitting direction; The light-emitting end ridge (1) is an inclined ridge that is narrow at the front and wide at the back. The width of the light-emitting end ridge (1) that contacts the active multimode interferometer (2) is 6~10μm, and the width of the light-emitting end ridge (1) that contacts the light-emitting cavity surface is 3~5μm. The width of the DBR ridges (4) with different periods is 2~4μm, and the area of ​​the optical absorption region (5) accounts for 3%~10% of the area of ​​the upper surface of the P-side electrode.

2. The multi-period DBR superluminescent diode structure with an ultra-wide spectral width according to claim 1, characterized in that, The active multimode interferometer (2) has a parallelogram structure with a side length of 20~50μm.

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