Broadband chaotic laser generation device based on transistor laser current feedback

Abstract

The application relates to the field of semiconductor optoelectronics, and aims to solve the problems of limited spectrum bandwidth and complex perturbation system of existing semiconductor diode lasers, and provides a chaotic laser generation device based on a transistor laser collector current feedback structure, which comprises a transistor laser, an adder, a current source, a voltage source and an optical output port.The base electrode of the transistor laser is connected with the output port of the adder, the emitter electrode is connected with the negative electrode of the voltage source and the input end of the current source, the collector electrode is connected with the positive electrode of the voltage source and the first input end of the adder, and the second input end of the adder is connected with the output end of the current source.The chaotic laser signal with a standard bandwidth of 50GHz and a flatness better than 3dB can be generated, and the chaotic laser signal can be applied to the fields of chaotic synchronization and secret optical communication, high-speed random number key generation, laser radar, fiber network fault detection, ultra-wideband technology and distributed fiber sensing.

Description

Technical Field

[0001] This invention relates to the field of semiconductor optoelectronics, and in particular to a chaotic laser generating device based on a transistor laser collector current feedback structure. Background Technology

[0002] Chaotic lasers possess inherent randomness, initial condition sensitivity, low coherence, and wide spectral density. In recent years, chaotic lasers have shown significant application value in fields such as secure optical communication, ultra-wideband technology, lidar, fiber optic network fault detection, and distributed fiber optic sensing. Currently, methods for generating chaos using semiconductor lasers include optical feedback, optical injection, and photoelectric feedback.

[0003] Diode-structured semiconductor lasers have become the preferred light source for generating chaotic lasers due to their advantages such as low power consumption, long lifespan, and ease of integration. However, the relaxation oscillation frequency of diode lasers is only a few GHz, and the energy is mainly concentrated near the relaxation oscillation frequency, resulting in a narrow bandwidth and uneven spectrum in the generated chaotic laser, which greatly limits the practical application of chaotic lasers (IEEE Journal on Selected Topics in Quantum Electronics, 21(6):531-540, 2015).

[0004] To address the above issues, researchers have proposed various methods to improve the bandwidth of chaotic lasers. In 2011, Zhang Mingjiang et al. obtained a broadband chaotic laser with a bandwidth of 32.3 GHz with 80% bandwidth by injecting dual-wavelength external light into an external cavity optical feedback Fabry-Pérot laser (IEEE Photonics Technology Letters, 2011, 23(24): 1872-1874). In 2015, Lin Fanyi et al. enhanced the bandwidth of the original chaotic signal by 46% by converting the chaotic signal into an electrical signal, interacting it with a sinusoidal signal to form heterodyne chaos, and then mixing it with the original chaotic signal (OpticsExpress, 2015, 23(3): 2308-2319). However, all of the above schemes are based on diode lasers and rely on complex perturbation systems to improve the bandwidth and flatness of chaotic lasers, and the spectral bandwidth is limited.

[0005] A transistor laser is a type of transistor that combines the current control functionality of a transistor with the light emission functionality of a laser. A transistor laser can simultaneously produce an electrical signal output (collector current) and an optical signal output using a single electrical signal input (e.g., base current). This functional characteristic makes it highly valuable for applications in optical communication and optical signal processing. Summary of the Invention

[0006] This invention overcomes the problem of narrow bandwidth of chaotic laser spectrum generated by existing diode laser optical feedback structures, and provides a chaotic laser generating device based on transistor laser collector current feedback structure. It utilizes the characteristics of transistor lasers, such as high bandwidth, low relaxation oscillation peak, and simultaneous optical and electrical signal output, to generate chaotic laser signals with large standard bandwidth and good flatness.

[0007] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a broadband chaotic laser generating device based on transistor laser current feedback, comprising: a transistor laser, an adder, a current source, and a voltage source;

[0008] The base electrode of the transistor laser is connected to the output port of the adder, and the emitter electrode is connected to the negative terminal of the voltage source and the input terminal of the current source. The collector electrode of the transistor laser is connected to the positive terminal of the voltage source and is also connected to the first input terminal of the adder. The second input terminal of the adder is connected to the output terminal of the current source. The optical output port of the transistor laser outputs broadband chaotic laser light.

[0009] The transistor laser includes a collector electrode layer, a collector region material layer, a base region buffer layer, and a base region material layer disposed sequentially. On the side of the base region material layer away from the base region buffer layer, there is a non-connected base electrode layer and a current limiting layer. On the current limiting layer, there is a quantum well material layer, an upper limiting layer, an emitter region material layer, and an emitter electrode layer disposed sequentially.

[0010] The emitter region material layer is made of n-doped InP material; the upper confinement layer is made of InGaAsP material; the quantum well material layer is made of InGaAsP / InP material; the current confinement layer is made of n-doped InP and p-doped InP material to form a pn junction; the base region material layer is made of p-doped InGaAsP material; the base region buffer layer is made of InGaAsP material; and the collector region material layer is made of n-doped InP material.

[0011] The base electrode layer is located outside the current limiting layer.

[0012] The voltage source is used to control the internal parameters of the transistor laser.

[0013] The internal parameters of the transistor laser include linewidth broadening factor, carrier spontaneous emission lifetime, quantum well trapping time, and escape time.

[0014] Compared with the prior art, the present invention has the following advantages:

[0015] 1. This invention uses a three-port transistor laser to replace a diode laser to generate chaotic laser, breaking through the limitation of relaxation oscillation inside the laser and providing a novel method for generating broadband chaotic laser with a flat spectrum.

[0016] 2. This invention utilizes the characteristics of transistor lasers, such as high bandwidth, low relaxation oscillation peak, and simultaneous optical and electrical signal output, to generate broadband chaotic lasers with bandwidth exceeding 50GHz and flatness less than 3.5dB. These indicators are difficult to achieve using traditional methods.

[0017] 3. This invention utilizes the collector current output of the transistor laser itself as a feedback perturbation, achieving broadband chaotic laser signal generation without the need for an external perturbation source. The structure is very simple, stable, and inexpensive, making it highly valuable for widespread application. It can be widely used in fields such as chaotic synchronization and secure optical communication, high-speed random number key generation, lidar, fiber optic network fault detection, ultra-wideband technology, and distributed fiber optic sensing. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of a broadband chaotic laser generating device based on a transistor laser collector current feedback structure, provided in an embodiment of the present invention.

[0019] In the diagram: 1-Transistor laser, 2-Adder, 3-Current source, 4-Voltage source, 5-Optical output port;

[0020] Figure 2 This is a schematic diagram of the carrier distribution in a transistor laser according to an embodiment of the present invention;

[0021] Figure 3 This is a schematic diagram of the interface structure of the transistor laser used in Embodiment 2 of the present invention;

[0022] Figure 4 for Figure 3 The top view shows the emitter electrode above the base electrode layer, the emitter material layer, the upper confinement layer, and the quantum well material layer removed.

[0023] In the figure: 6-Emitter electrode, 7-Emitter material layer, 8-Upper confinement layer, 9-Quantum well material layer, 10-Current confinement layer, 11-Base electrode layer, 12-Base material layer, 13-Base buffer layer, 14-Collector material layer, 15-Collector electrode. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are some embodiments of the present invention, but 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.

[0025] Example 1

[0026] like Figure 1 As shown, Embodiment 1 of the present invention provides a broadband chaotic laser generation device based on transistor laser current feedback, comprising: a transistor laser 1, an adder 2, a current source 3, and a voltage source 4; the base electrode of the transistor laser 1 is connected to the output port of the adder 2, and the emitter electrode is connected to the negative terminal of the voltage source 4 and the input terminal of the current source 3; the collector electrode of the transistor laser 1 is connected to the positive terminal of the voltage source 4, and the collector electrode is also connected to the first input terminal of the adder 2, the second input terminal of the adder 2 is connected to the output terminal of the current source 3, and the optical output port 5 of the transistor laser 1 outputs broadband chaotic laser.

[0027] In this embodiment, the transistor laser 1 operates in common-emitter mode. The emitter electrode 6 is grounded, and the base electrode 11 is connected to the sum of the current output from the current source 3 in the adder 2 and the current output from the collector electrode 15 of the transistor laser, which serves as the driving current for the transistor laser 1. The collector electrode 15 is connected to the positive terminal of the voltage source 4, and the emitter electrode 6 is connected to the negative terminal of the voltage source 4. The voltage source 4 serves as the collector-emitter voltage source for the transistor laser 1. The collector-emitter voltage source is controlled by the voltage source 4 to control the linewidth broadening factor, base carrier spontaneous emission lifetime, and other internal parameters of the transistor laser 1.

[0028] Furthermore, in this embodiment, the transistor laser 1 adopts an npn transistor structure. For example... Figure 2 As shown, where E c : Conductor belt; E v Price band; I E Emitter current; I C Collector current; I B : Base current; e: electron; h: hole; hv: photon; QW: quantum well; n-Emitter: n-type doped emitter region; p-Base: p-type doped base region; n-Collector: n-type doped collector region. When the collector junction of the transistor laser is reverse biased, the minority carriers in the base region are distributed at an angle. Some of these minority carriers are captured by the quantum well material layer and undergo stimulated recombination within the quantum well material layer, outputting laser light at the chaotic laser output port 5. The remaining minority carriers, upon reaching the base-collector boundary, diffuse due to the different doping of the base and collector materials, forming a diffusion current, i.e., the collector current. The collector current is output from the collector electrode and connected to the first input port of adder 2. The current from current source 3, connected to the second input port of adder 2, is added to form the current feedback modulation of transistor laser 1, thereby perturbing the carrier concentration inside the base material layer and outputting chaotic laser light at the output port 5.

[0029] Example 2

[0030] Similar to Embodiment 1, Embodiment 1 of the present invention provides a broadband chaotic laser generating device based on transistor laser current feedback, comprising: a transistor laser 1, an adder 2, a current source 3, and a voltage source 4; the base electrode of the transistor laser 1 is connected to the output port of the adder 2, and the emitter electrode is connected to the negative terminal of the voltage source 4 and the input terminal of the current source 3; the collector electrode of the transistor laser 1 is connected to the positive terminal of the voltage source 4, and the collector electrode is also connected to the first input terminal of the adder 2, the second input terminal of the adder 2 is connected to the output terminal of the current source 3, and the optical output port 5 of the transistor laser 1 outputs broadband chaotic laser.

[0031] Unlike Example 1, as Figure 3 As shown, in this embodiment, the transistor laser 1 includes a collector electrode layer 15, a collector region material layer 14, a base region buffer layer 13, and a base region material layer 12, which are sequentially disposed. On the side of the base region material layer 12 away from the base region buffer layer 13, there are a non-connected base electrode layer 11 and a current limiting layer 10. On the current limiting layer 10, there are a quantum well material layer 9, an upper limiting layer 8, an emitter region material layer 7, and an emitter electrode layer 6, which are sequentially disposed.

[0032] Specifically, in this embodiment, the emitter material layer 7 is made of n-doped InP material; the upper confinement layer 8 is made of InGaAsP material; the quantum well material layer 9 is made of InGaAsP / InP material; the current confinement layer 10 is formed by n-doped InP and p-doped InP materials to form a pn junction; the base region material layer 12 is made of p-doped InGaAsP material; the base region buffer layer 13 is made of InGaAsP material; and the collector region material layer 14 is made of n-doped InP material.

[0033] In this embodiment, the emitter region material layer is n-doped, the base region material layer is p-doped, and the collector region material layer is n-doped. Therefore, it includes an n-type material layer, a p-type material layer, a quantum well layer, and another n-type material layer arranged sequentially from bottom to top. The quantum well layer is disposed above the p-type material layer, which, compared to the existing structure where the quantum well layer is disposed in the middle of the p-type material layer, reduces the contamination of the quantum well by p-doping.

[0034] Specifically, in this embodiment, the quantum well material layer 9, the upper confinement layer 8, the emitter material layer 7, and the emitter electrode layer 6 protrude relative to the chip surface to form a ridge waveguide, and the base electrode layer 11 is disposed outside the current confinement layer 10. The function of the current confinement layer 10 is to ensure that carriers injected from the emitter pass only through the current confinement channel, thereby reducing the influence of surface non-radiative recombination centers. Therefore, in this embodiment, a current confinement layer 10 is disposed on each side of the ridge waveguide, such as... Figures 3-4As shown, the two base electrode layers 11 can also be connected together in a ring outside the current limiting layer 10.

[0035] In summary, this invention provides a broadband chaotic laser generation device based on transistor laser current feedback. Feedback is achieved through the collector current of the transistor laser. Because the minority carriers in the base region are tilted when the collector junction of the transistor laser is reverse-biased, its equivalent carrier lifetime is only on the order of ps, far less than the nanosecond-order carrier lifetime of traditional diode lasers. This effectively suppresses the influence of relaxation oscillations and significantly increases the direct modulation bandwidth, thereby obtaining a broadband chaotic laser with a bandwidth exceeding 50 GHz and a flatness of less than 3.5 dB.

[0036] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A broadband chaotic laser generating device based on transistor laser current feedback, characterized in that, include: Transistor laser (1), adder (2), current source (3), voltage source (4); The base electrode of the transistor laser (1) is connected to the output port of the adder (2), and the emitter electrode is connected to the negative terminal of the voltage source (4) and the input terminal of the current source (3). The collector electrode of the transistor laser (1) is connected to the positive terminal of the voltage source (4), and the collector electrode is also connected to the first input terminal of the adder (2). The second input terminal of the adder (2) is connected to the output terminal of the current source (3). The optical output port (5) of the transistor laser (1) outputs broadband chaotic laser light.

2. The broadband chaotic laser generating device based on transistor laser current feedback according to claim 1, characterized in that, The transistor laser (1) includes a collector electrode layer (15), a collector region material layer (14), a base region buffer layer (13), and a base region material layer (12) disposed sequentially. On the side of the base region material layer (12) away from the base region buffer layer (13), there is a non-connected base electrode layer (11) and a current confinement layer (10). On the current confinement layer (10), there is a quantum well material layer (9), an upper confinement layer (8), an emitter region material layer (7), and an emitter electrode layer (6) disposed sequentially.

3. The broadband chaotic laser generating device based on transistor laser current feedback according to claim 2, characterized in that, The emitter material layer (7) is made of n-doped InP material; the upper confinement layer (8) is made of InGaAsP material; the quantum well material layer (9) is made of InGaAsP / InP material; the current confinement layer (10) is made of n-doped InP and p-doped InP material to form a pn junction; the base material layer (12) is made of p-doped InGaAsP material; the base buffer layer (13) is made of InGaAsP material; and the collector material layer (14) is made of n-doped InP material.

4. The broadband chaotic laser generating device based on transistor laser current feedback according to claim 2, characterized in that, The base electrode layer (11) is disposed outside the current limiting layer (10).

5. The broadband chaotic laser generating device based on transistor laser current feedback according to claim 1, characterized in that, The voltage source (4) is used to control the internal parameters of the transistor laser (1).

6. The broadband chaotic laser generating device based on transistor laser current feedback according to claim 1, characterized in that, The internal parameters of the transistor laser (1) include linewidth broadening factor, carrier spontaneous emission lifetime, quantum well trapping time, and escape time.

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