Sofa-dfb intercoupled double feedback hybrid integrated chaotic semiconductor laser

Abstract

This invention discloses an SOA-DFB mutually coupled dual-feedback hybrid integrated chaotic semiconductor laser, relating to the field of semiconductor optoelectronic integration technology. The laser comprises a DFB laser chip, an SOA chip, a collimating lens, and a double-reflection transmission mirror arranged sequentially and coaxially. By adding an active device, the SOA chip, directly coupled to the DFB laser chip, the invention utilizes the broadband ASE noise generated by the SOA chip to inject backward into the DFB laser chip, causing disturbances to the optical field and intercarrier interactions within the laser. Simultaneously, combined with the strong-weak imbalance dual-cavity competition mechanism caused by the short and long external cavities formed by the front and rear reflecting surfaces of the double-reflection transmission mirror, the periodicity of a single feedback loop is effectively broken. This allows for the realization of high-bandwidth, low-delay, and high-power chaotic laser output without the need for complex optical injection systems and expensive optical isolators, offering advantages such as small size, low cost, high integration, and good stability.

Description

Technical Field

[0001] This invention relates to the field of semiconductor optoelectronic integration technology, specifically to an SOA-DFB mutually coupled dual-feedback hybrid integrated chaotic semiconductor laser, which generates broadband chaos based on the mutual coupling of SOA (semiconductor optical amplifier) ​​and DFB (distributed feedback) lasers and an external dual-feedback structure. Background Technology

[0002] Chaotic lasers are a typical type of nonlinear optical signal, exhibiting noise-like characteristics such as large-amplitude, irregular oscillations in time, a wide-spectrum, continuous power spectrum, a delta-shaped autocorrelation curve, and a complex, high-dimensional phase diagram. Therefore, they possess irreplaceable advantages in fields such as secure optical communication, high-speed random number generation, chaotic lidar, chaotic photonic computing, and distributed fiber optic sensing. Traditional chaotic laser generation devices are mostly constructed using semiconductor lasers combined with various externally discrete mirrors and other optical components, resulting in fatal flaws such as large size, susceptibility to environmental vibrations and temperature changes, low coupling efficiency, and poor long-term system stability. To meet the stringent requirements of modern optoelectronic systems for lightweight design, low power consumption, and high stability, the integration of chaotic lasers has become an inevitable trend in this field.

[0003] To address the aforementioned issues, current international research on integrated chaotic lasers primarily focuses on the monolithic photonic integration approach, which involves simultaneously integrating active regions, passive waveguides, feedback cavities, and modulation structures on a single substrate such as InP or silicon photonics. In 2017, Ohara et al. from Saitama University, Japan, proposed a mutually coupled photonic integrated chaotic semiconductor laser chip based on a Y-shaped waveguide structure. This structure uses a Y-shaped waveguide as the coupling medium to generate chaotic laser output under the combined perturbation of optical feedback and optical injection, and achieves chaotic synchronization. [Ohara S, DalBosco AK, Ugajin K, et al. Dynamics-dependent synchronization in on-chipcoupled semiconductor lasers[J]. Physical Review E, 2017,96(3): 032216.]. In 2019, Qiao Lijun et al. proposed a wavelength-tunable broadband chaotic semiconductor laser chip (see patent: Wavelength-tunable broadband chaotic semiconductor laser chip, patent number: 201910373323.8). This chip consists of two three-segment DBR lasers injected into each other. By adjusting the injection current in the grating region or phase region, precise tuning of the center wavelength can be achieved, thereby generating broadband chaotic laser output. In 2023, Zhang Mingjiang et al. also proposed a four-segment monolithically integrated chaotic laser with active feedback based on a DBR external cavity (see patent: Four-segment monolithically integrated chaotic laser with active feedback based on a DBR external cavity, patent number: 202311171873.4). This chip integrates a DFB laser region, a semiconductor optical amplification region, a phase region, and a distributed Bragg grating region. It utilizes a DBR grating as an external cavity feedback element, effectively generating chaotic dynamics through an active feedback mechanism.

[0004] However, the aforementioned integrated chaotic semiconductor lasers all employ monolithic integration, which is a chip-level integrated structure. In practical production applications, the complex chip growth and fabrication processes lead to high manufacturing costs, hindering large-scale application. Researchers have proposed hybrid integration schemes. Utilizing mature commercial devices for hybrid integration or modular packaging is an effective way to achieve low-cost, practical chaotic light sources. In 2018, Xu Yuhang et al. from Taiyuan University of Technology proposed an integrated optical feedback semiconductor chaotic laser, which uses a DFB laser chip, a double-reflecting transmission mirror, and a lens fiber. This structure, based on a single feedback structure, produces a relatively obvious chaotic laser with significant time delay characteristics, but this structure suffers from the problem of difficulty in further improving the chaotic laser bandwidth [Xu Yuhang. Development of Hybrid Integrated Chaotic Semiconductor Laser [D]. Taiyuan University of Technology, 2018.]. In 2024, Liu Xiong, Jia Zhiwei, and others developed an integrated broadband chaotic semiconductor laser (Liu Xiong, Jia Zhiwei, et al. Integrated Broadband Chaotic Semiconductor Laser [J]. Progress in Laser & Optoelectronics, 2024, 61(15): 1514003.). This device is based on a short-cavity distributed feedback (DFB) semiconductor laser chip with fiber / space dual-end output. It adopts an integrated spatial optical feedback structure and integrates a reflector and adjustment device with the laser. The external strong light feedback provided by the reflector is used to perturb the short-cavity DFB laser to generate chaos. Although the device achieves a chaotic bandwidth of over 30 GHz, its overall size is still relatively large (16cm×8cm×7cm), and the structure contains a mechanical adjustment device, which is not conducive to the miniaturization and long-term stability of the device. Summary of the Invention

[0005] To address the problems of limited bandwidth, significant time delay characteristics, excessive power consumption due to too many passive components, complex processes, or low system integration in existing integrated technologies for chaotic lasers, this invention provides a dual-feedback hybrid integrated chaotic semiconductor laser based on SOA and DFB mutual coupling. It utilizes external double-sided coated reflective mirrors to form dual external cavity feedback, and combines the beat frequency effect generated by the reverse injection of ASE noise from SOA to introduce additional nonlinear effects, significantly improving the bandwidth and complexity of the chaotic laser. At the same time, it effectively amplifies the output chaotic light power gain by combining the amplification function of SOA semiconductor amplifier.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: an SOA-DFB mutually coupled dual feedback hybrid integrated chaotic semiconductor laser, comprising a DFB laser chip, an SOA chip, a collimating lens, and a dual-reflection transmission mirror arranged sequentially and coaxially; the dual-reflection transmission mirror includes two reflecting surfaces, namely a front reflecting surface and a rear reflecting surface. The DFB laser chip is directly coupled to the SOA chip. The DFB laser chip generates a single longitudinal mode laser signal, which is then directly injected into the SOA chip, which amplifies the laser signal. The collimating lens collimates the amplified laser signal. The front and rear reflecting surfaces of the dual-reflection transmission mirror reflect the collimated laser signal to form short external cavity feedback and long external cavity feedback, respectively. The two feedback beams return to the SOA chip and are amplified twice before being injected into the DFB laser chip. The reverse ASE noise generated by the SOA chip is directly injected into the DFB laser chip, and the forward ASE noise is injected into the DFB laser chip after external reflection. The two feedback beams, the reverse ASE noise, and the forward ASE noise together perturb the DFB laser chip, causing it to output a broadband chaotic laser signal, which is then output from the rear end of the dual-reflection transmission mirror after passing through the SOA chip, the collimating lens, and the dual-reflection transmission mirror in sequence.

[0007] The reflectivity of the front reflecting surface of the dual-reflection transmission mirror is lower than that of the rear reflecting surface, and the front reflecting surface is the surface close to the DFB laser chip.

[0008] The reflectivity of the front reflecting surface of the dual-reflection transmission mirror is 5%-15%, and the reflectivity of the rear reflecting surface is 30%-50%.

[0009] Both ends of the DFB laser chip are naturally cleaved ends, and an antireflection coating with a reflectivity of 0.1 to 0.2 is provided at the end closer to the SOA chip, while an antireflection coating with a reflectivity greater than 0.9 is provided at the end farther from the SOA chip.

[0010] The SOA chip operates in the saturation gain region.

[0011] The SOA-DFB mutually coupled dual feedback hybrid integrated chaotic semiconductor laser further includes a focusing mirror and a lens fiber disposed at the rear end of the dual-reflection transmission mirror. The focusing mirror is used to couple the broadband chaotic laser signal output from the dual-reflection transmission mirror into the lens fiber and then output it.

[0012] The SOA-DFB mutually coupled dual feedback hybrid integrated chaotic semiconductor laser further includes a package housing, in which a heat sink and a thermoelectric cooler are disposed. The DFB laser chip and the SOA chip are disposed on the heat sink, and the thermoelectric cooler is disposed below the heat sink to control the temperature of the DFB laser chip and the SOA chip.

[0013] The encapsulation housing also includes a pad; the collimating lens, dual-reflection transmission mirror, focusing mirror, and lens fiber are all mounted on the pad, and the pad is used to make the collimating lens, dual-reflection transmission mirror, focusing mirror, and lens fiber coaxial with the DFB laser chip.

[0014] The encapsulation housing is a standard 14-pin butterfly-shaped housing.

[0015] The DFB laser chip and the SOA semiconductor optical amplifier chip are either two independent chips or integrated into a single chip.

[0016] Compared with the prior art, the present invention has the following advantages: 1. This invention provides an SOA-DFB mutually coupled dual-feedback hybrid integrated chaotic semiconductor laser. By adding an active device SOA chip directly coupled to the DFB laser chip, not only is the feedback light intensity enhanced and the output chaotic laser power increased, but also the broadband ASE noise generated by the SOA chip is injected back into the DFB laser chip. The beat frequency effect between the SOA's ASE noise and the laser signal excites high-frequency perturbation of the charge carriers in the DFB laser, significantly improving the effective bandwidth of the chaotic laser. At the same time, combined with the strong and weak unbalanced dual-cavity competition mechanism caused by the short and long external cavities formed by the front and rear reflecting surfaces of the dual-reflection transmission mirror, the periodicity of the single feedback loop is effectively broken, the time delay characteristic (TDS) is suppressed, and the unpredictability of chaos is improved. High bandwidth, low time delay characteristic, and high power chaotic laser output can be achieved without complex optical injection systems and expensive optical isolators. 2. The present invention has a simple structure and small size. Each optical component can adopt a coaxial integrated design and be packaged in a standard butterfly tube shell, which not only improves the integration degree, but also greatly reduces the size and manufacturing cost. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of an SOA-DFB mutually coupled dual feedback hybrid integrated chaotic semiconductor laser provided in an embodiment of the present invention; In the diagram: 1 is the DFB laser chip, 2 is the SOA chip, 3 is the heat sink, 4 is the semiconductor cooling chip, 5 is the collimating lens, 6 is the double-reflection transmission mirror, 7 is the focusing lens, 8 is the pad, and 9 is the lens fiber. Detailed Implementation

[0018] 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.

[0019] like Figure 1As shown, this embodiment of the invention provides an SOA-DFB mutually coupled dual-feedback hybrid integrated chaotic semiconductor laser, comprising: a DFB laser chip 1, an SOA chip 2, a collimating lens 5, and a dual-reflection transmission mirror 6. The dual-reflection transmission mirror 6 includes two reflective surfaces, namely a front reflective surface and a rear reflective surface.

[0020] The DFB laser chip 1, SOA chip 2, collimating lens 5, and double-reflecting transmission mirror 6 are arranged sequentially and coaxially. The DFB laser chip 1 and SOA chip 2 are directly coupled. The DFB laser chip 1 generates a single longitudinal mode laser signal, which is then directly injected into the SOA chip 2. The SOA chip 2 amplifies the laser signal. The collimating lens 5 collimates the amplified laser signal. The front and rear reflective surfaces of the double-reflecting transmission mirror 6 reflect the collimated laser signal to form short external cavity feedback and long external cavity feedback, respectively. The two feedback beams return to the SOA chip 2 and are amplified twice before being injected into the DFB laser chip 1. The reverse ASE noise generated by the SOA chip 2 is directly injected into the DFB laser chip 1, and the forward ASE noise is injected into the DFB laser chip 1 after external reflection. The two feedback beams, the reverse ASE noise, and the forward ASE noise together perturb the DFB laser chip 1, causing it to output a broadband chaotic laser signal, which is then output from the rear end face of the double-reflecting transmission mirror 6 after passing through the SOA chip 2, collimating lens 5, and double-reflecting transmission mirror 6 in sequence.

[0021] The reflectivity of the front reflecting surface of the dual-reflection transmission mirror 6 is lower than that of the rear reflecting surface, and the front reflecting surface is the surface close to the DFB laser chip 1.

[0022] Specifically, in this embodiment, the reflectivity of the front reflecting surface of the dual-reflection transmission mirror 6 is 5%-15%, and the reflectivity of the rear reflecting surface is 30%-50%.

[0023] In this embodiment, the collimating lens 5 serves to collimate the divergent light emitted by the DFB laser chip into parallel light, and the dual-reflection transmission mirror 6 serves to form a feedback short external cavity and a long external cavity.

[0024] Furthermore, in this embodiment, both ends of the DFB laser chip 1 are naturally cleaved end faces with a reflectivity of 0.32. In order to improve the output power of the output side and reduce the output power of the other side, an antireflection coating with a reflectivity of 0.1~0.2 is provided at the end closer to the SOA chip 2, and an antireflection coating with a reflectivity greater than 0.9 is provided at the end farther away from the SOA chip 2.

[0025] Furthermore, in this embodiment, the SOA chip 2 operates in the saturation gain region. Operating in the saturation gain region, the SOA chip 2 not only amplifies the single-longitudinal-mode laser generated by the DFB laser chip 1 under DC bias, but also injects its generated broadband spontaneous emission (ASE) noise into the DFB laser chip 1 in two paths, creating a beat frequency effect with the laser signal and causing random disturbances to the laser's carrier density.

[0026] Furthermore, the SOA-DFB mutually coupled dual-feedback hybrid integrated chaotic semiconductor laser of this embodiment also includes a focusing mirror 7 and a lens fiber 9 disposed at the rear end of the dual-reflection transmission mirror 6. The focusing mirror 7 is used to converge the broadband chaotic laser signal output from the dual-reflection transmission mirror 6 and couple it into the lens fiber 9 for output. The focusing mirror 7, in conjunction with the collimating lens 5, can improve the overall coupling efficiency of the chaotic laser.

[0027] Furthermore, this embodiment of an SOA-DFB mutually coupled dual-feedback hybrid integrated chaotic semiconductor laser also includes a package housing. A heat sink 3 and a thermoelectric cooler 4 are disposed within the package housing. The DFB laser chip 1 and the SOA chip are disposed on the heat sink 3, and the thermoelectric cooler 4 is disposed below the heat sink 3 to control the temperature of the DFB laser chip 1 and the SOA chip. The heat sink 3, located between the DFB laser chip 1 and the thermoelectric cooler 4, serves to uniformly conduct heat.

[0028] Furthermore, in this embodiment, a pad 8 is also provided inside the packaging housing; the collimating lens 5, the dual-reflection transmission mirror 6, the focusing mirror 7, and the lens fiber 9 are all disposed on the pad 8, and the pad 8 is used to make the collimating lens 5, the dual-reflection transmission mirror 6, the focusing mirror 7, and the lens fiber 9 coaxially disposed with the DFB laser chip 1.

[0029] Furthermore, in this embodiment, the encapsulation housing is a standard 14-pin butterfly shell. Alternatively, the encapsulation housing can also be a coaxial pigtail module. A coaxial pigtail module is a device using a coaxial (TO-CAN) hermetic encapsulation, which integrates the optical fiber into the encapsulation housing in a fixed pigtail form, forming a non-pluggable optical fiber output structure.

[0030] Furthermore, in this embodiment, the DFB laser chip 1 and SOA chip 2 are two independent chips, closely arranged and located on the heat sink 3, with no optical isolation elements between them, ensuring bidirectional free transmission of the light field and noise. Alternatively, the DFB laser chip 1 and SOA chip 2 can also be monolithically integrated into a single chip. The integrated chip is disposed on the heat sink 3.

[0031] The working principle of this invention is as follows: A DFB laser chip 1 generates a single-longitudinal-mode laser under DC bias and directly injects it into an SOA chip 2. The SOA chip 2 is in a high-gain state, amplifying the signal light. The amplified beam is collimated by a collimating lens 5 and then incident on a dual-reflection transmission mirror 6. The front surface A (low reflectivity, e.g., 5%-15%) of the dual-reflection transmission mirror 6 provides short external cavity feedback to the DFB laser chip 1; the rear surface B (medium-high reflectivity, e.g., 30%-50%) provides long external cavity feedback to the DFB laser chip 1. Specifically, the two feedback beams reflected from the front surface A and the rear surface B carry different phase delays and are coupled back to the SOA semiconductor optical amplifier chip 2 after passing through the collimating lens 5. The feedback light is amplified twice (double-pass amplification) in the SOA chip 2, obtaining extremely high feedback intensity, and is finally injected into the DFB laser chip 1. Simultaneously, SOA chip 2 generates ASE noise during operation. The reverse ASE noise is directly injected into DFB laser chip 1, while the forward ASE noise is also injected into DFB laser chip 1 after reflection by external components such as collimating lens 5 and double-reflecting transmission mirror 6. This broadband ASE noise injected into DFB laser chip 1 disturbs the optical field and intercarrier interactions within the laser. Under the combined effects of strong feedback, dual-cavity competition, and noise disturbance, DFB laser chip 1 enters a high-bandwidth chaotic state. Ultimately, the portion of the chaotic laser transmitted through double-reflecting transmission mirror 6 is coupled into the lens fiber 8 by focusing lens 7 and output, thus achieving the output of a broadband chaotic laser.

[0032] In summary, this invention utilizes the non-isolated, mutually coupled structure of the DFB laser chip and the SOA chip to cleverly combine the nonlinear gain and noise characteristics of active devices with the dual feedback delay characteristics of passive devices, significantly improving the effective bandwidth of chaotic lasers; and suppressing time delay characteristics (TDS), achieving high bandwidth, low time delay characteristics, and high power chaotic laser output. The entire structure can be fixed in a common commercial 14-pin butterfly laser tube housing, realizing a small-sized, high-bandwidth, and highly complex integrated chaotic light source.

[0033] 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 SOA-DFB mutually coupled dual-feedback hybrid integrated chaotic semiconductor laser, characterized in that, It includes a DFB laser chip (1), an SOA chip (2), a collimating lens (5), and a double-reflection transmission mirror (6) arranged sequentially and coaxially; the double-reflection transmission mirror (6) includes two reflecting surfaces, namely a front reflecting surface and a rear reflecting surface; The DFB laser chip (1) is directly coupled to the SOA chip (2); the DFB laser chip (1) generates a single longitudinal mode laser and then directly injects it into the SOA chip (2), and the SOA chip (2) amplifies the laser signal; the collimating lens (5) is used to collimate the amplified laser signal; the front and rear reflecting surfaces of the double-reflecting transmission mirror (6) are used to reflect the collimated laser signal to form short external cavity feedback and long external cavity feedback respectively; the two feedback beams return to the SOA chip (2) and are injected into the DFB laser chip (1) after secondary amplification; the reverse ASE noise generated by the SOA chip (2) is directly injected into the DFB laser chip (1), and the forward ASE noise is injected into the DFB laser chip (1) after external reflection; the two feedback beams, the reverse ASE noise, and the forward ASE noise together disturb the DFB laser chip (1) to make it output a broadband chaotic laser signal, and output from the rear end face of the double-reflecting transmission mirror (6) after passing through the SOA chip (2), the collimating lens (5), and the double-reflecting transmission mirror (6) in sequence.

2. The SOA-DFB mutually coupled dual-feedback hybrid integrated chaotic semiconductor laser according to claim 1, characterized in that, The reflectivity of the front reflecting surface of the dual-reflection transmission mirror (6) is lower than that of the rear reflecting surface, and the front reflecting surface is the surface close to the DFB laser chip (1).

3. The SOA-DFB mutually coupled dual-feedback hybrid integrated chaotic semiconductor laser according to claim 1, characterized in that, The reflectivity of the front reflecting surface of the dual-reflection transmission mirror (6) is 5%-15%, and the reflectivity of the rear reflecting surface is 30%-50%.

4. The SOA-DFB mutually coupled dual-feedback hybrid integrated chaotic semiconductor laser according to claim 1, characterized in that, Both ends of the DFB laser chip (1) are natural cleavage end faces, and an antireflection film with a reflectivity of 0.1~0.2 is provided at the end closer to the SOA chip (2), and an antireflection film with a reflectivity greater than 0.9 is provided at the end farther away from the SOA chip (2).

5. The SOA-DFB mutually coupled dual-feedback hybrid integrated chaotic semiconductor laser according to claim 1, characterized in that, The SOA chip (2) operates in the saturation gain region.

6. The SOA-DFB mutually coupled dual-feedback hybrid integrated chaotic semiconductor laser according to claim 1, characterized in that, It also includes a focusing lens (7) and a lens fiber (9) disposed at the rear end of the dual-reflection transmission mirror (6). The focusing lens (7) is used to couple the broadband chaotic laser signal output from the dual-reflection transmission mirror (6) into the lens fiber (9) and then output it.

7. The SOA-DFB mutually coupled dual-feedback hybrid integrated chaotic semiconductor laser according to claim 6, characterized in that, It also includes a packaging housing, in which a heat sink (3) and a semiconductor cooling chip (4) are disposed. The DFB laser chip (1) and SOA chip are disposed on the heat sink (3), and the semiconductor cooling chip (4) is disposed below the heat sink (3) to control the temperature of the DFB laser chip (1) and SOA chip.

8. The SOA-DFB mutually coupled dual-feedback hybrid integrated chaotic semiconductor laser according to claim 7, characterized in that, The encapsulation housing is also provided with a pad (8); the collimating lens (5), the double reflection transmission mirror (6), the focusing mirror (7) and the lens fiber (9) are all disposed on the pad (8), and the pad (8) is used to make the collimating lens (5), the double reflection transmission mirror (6), the focusing mirror (7) and the lens fiber (9) coaxial with the DFB laser chip (1).

9. The SOA-DFB mutually coupled dual-feedback hybrid integrated chaotic semiconductor laser according to claim 7, characterized in that, The encapsulation housing is a standard 14-pin butterfly-shaped housing.

10. The SOA-DFB mutually coupled dual-feedback hybrid integrated chaotic semiconductor laser according to claim 1, characterized in that, The DFB laser chip (1) and the SOA semiconductor optical amplifier chip (2) are two independent chips or a single chip integrated into one chip.

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