Square wave optical signal source generation system and method

Abstract

The invention discloses a square wave optical signal source generation system and method. The system comprises a VCSEL laser, a polarization-maintaining beam splitter and a reflector. The VCSEL laser firstly has a good linear polarization characteristic, light beams emitted by the VCSEL laser are divided into TM and TE orthogonal mode light beams through the polarization-maintaining beam splitter, the TE mode is a lasing mode, and the TM mode is strongly suppressed. The TE mode is fed back and coupled to the VCSEL resonant cavity, so that the generation of a high-quality square wave signal is realized, and a high-quality light source is provided for the fields of optical communication, displacement sensing, measurement and the like; and meanwhile, the system is very simple in structure and easy to realize, and the complexity and the cost of realizing the square wave optical signal are greatly reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of lasers and relates to a square wave optical signal source generation system and method. Background Art

[0002] Signal sources play a vital role in electronic engineering and related fields. They are widely used in communications, electronic circuits, automatic control, scientific experiments and other fields. The main function of a signal source is to generate electrical signals of specific frequency, amplitude and waveform, and provide necessary input signals for testing and debugging of equipment and systems. These input signals are not only the basis for verifying equipment performance, but also the key to ensuring the normal operation of the system.

[0003] Among many types of signal sources, square wave optical signal sources have attracted much attention for their unique advantages. The signal generated by the square wave optical signal source has extremely clear rising and falling edges. This feature enables it to efficiently transmit digital information through simple encoding of "0" and "1". This feature has a wide range of application value in digital communication, data processing, digital circuits and other fields. Especially in modern optical communication technology, the generation of square wave optical signal sources is particularly important. With the continuous improvement of data transmission speed and the continuous advancement of communication technology, the demand for high-speed, stable and reliable optical signal sources is becoming increasingly urgent. With its excellent performance, the square wave optical signal source has become one of the core components for realizing high-speed optical communication. It can not only meet the needs of high-speed data transmission, but also maintain the stability and reliability of the signal in a complex communication environment, providing strong support for the development of modern optical communication technology.

[0004] However, the generation of square wave optical signal sources faces many technical challenges. Traditional methods of generating square wave optical signals mainly rely on electronic switches and laser modulation. Although these methods are effective to a certain extent, they often lead to complex system structures, high costs, long response times, and insufficient flexibility in practical applications. These problems seriously restrict the application of square wave optical signal sources in high-performance optical communication systems. Summary of the invention

[0005] The purpose of the present invention is to solve the technical problems in the prior art of complex structure, high cost, long response time and insufficient flexibility in practical applications when generating square wave signals, and to provide a square wave optical signal source generation system and method.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions: A first aspect of the present invention provides a square wave optical signal source generation system, comprising a VCSEL laser, a polarization-maintaining beam splitter and a reflector; The light beam emitted by the VCSEL laser is divided into a TM mode light beam and a TE mode light beam by a polarization-maintaining beam splitter; a reflector is arranged on the propagation path of the TE mode light beam; the TE mode light beam is reflected by the reflector and coupled into the resonant cavity of the VCSEL laser to realize the output of a square wave optical signal.

[0007] Furthermore, a beam splitter is provided between the polarization-maintaining beam splitter and the VCSEL laser, and the beam splitter splits the light beam reflected by the VCSEL laser into two beams, one beam propagates to the polarization-maintaining beam splitter, and the other beam is output through the optical isolator.

[0008] Furthermore, a collimator is arranged between the beam splitter and the VCSEL laser.

[0009] Furthermore, the beam splitter splits the beam in a 50:50 ratio.

[0010] Furthermore, the mode of the optical isolator is TE mode.

[0011] Furthermore, a collimator is provided on the propagation path of the output beam of the optical isolator.

[0012] A second aspect of the present invention provides a method for generating a square wave optical signal source, comprising the following steps: S1, splitting the light beam emitted by the VCSEL laser to obtain a first light beam and a second light beam; S2, performing polarization splitting on the second light beam to obtain a TM mode light beam and a TE mode light beam; S3, reflects the TE mode light beam back through the reflector, and couples it into the VCSEL resonant cavity through optical feedback to achieve square wave optical signal output.

[0013] Furthermore, the optical feedback distance can be adjusted as required.

[0014] Furthermore, the TE mode light beam is reflected back through a reflector and coupled into the VCSEL resonant cavity through optical feedback to realize the output of square wave optical signal, specifically: By adjusting the length of the external feedback cavity, the relaxation oscillation frequency of the TE mode light beam and the external cavity feedback frequency can be resonated. The relaxation oscillation can be excited by optical feedback and phase locking can be achieved, thereby realizing square wave signal output.

[0015] Furthermore, the relaxation oscillation frequency of the TE mode light beam and the external cavity light feedback frequency are resonated by adjusting the light feedback distance.

[0016] Compared with the prior art, the present invention has the following beneficial effects: The present invention discloses a square wave optical signal source generation system. By utilizing the orthogonal polarization characteristics of the laser, the present invention successfully separates the light beam emitted by the VCSEL laser into two independent light beams of TM mode and TE mode. This design not only ensures the purity of the two mode light beams, but also provides a basis for subsequent regulation; by setting a reflector on the propagation path of the TE mode light beam, a feedback modulation loop is formed. This structure helps the light beam to reflect multiple times in the cavity, increases the interaction time between the light beam and the gain medium, thereby improving the stability and output efficiency of the laser; an optical isolator is set on the detection light path to achieve mode selection, and by selecting the TE mode output, the output of the square wave signal is achieved; the laser system of the present invention has a compact structure, the connection between the components is simple and clear, and it is easy to integrate with other optical elements or systems. This design not only improves the flexibility of the system, but also provides convenience for subsequent expansion and upgrading; compared with traditional square wave optical signal sources, the components used in the present invention are relatively simple and low in cost, thereby achieving higher cost-effectiveness.

[0017] Furthermore, the beam splitter divides the reflected light into two paths, reducing the loss and interference of the optical signal on a single path. In particular, the path output through the optical isolator can be used as an independent monitoring channel to evaluate the performance of the VCSEL laser and the integrity of the light beam. This design helps to ensure the quality of the beam entering the polarization-maintaining beam splitter, thereby improving the quality of the square wave optical signal finally generated. The beam splitting achieved by the beam splitter makes the maintenance and debugging of the system more intuitive and simple. When the system needs to be calibrated or troubleshooted, the light beam output by the optical isolator can be used for rapid positioning and analysis, which effectively shortens maintenance time and reduces maintenance costs.

[0018] Furthermore, the beam splitter accurately splits the light beam reflected by the VCSEL laser into two beams at a 50:50 ratio, ensuring that each optical signal has the same intensity and stability. The system does not require additional optical attenuators or amplifiers to balance the intensity of the optical signal, thereby reducing the complexity and cost of the system.

[0019] Furthermore, the present invention discloses a method for generating a square wave optical signal source, which uses a beam splitter to evenly split the light beam emitted by a VCSEL laser into two beams, providing a reliable basis for subsequent polarization splitting and optical feedback. The second light beam is polarized and split by a polarization-maintaining beam splitter to accurately separate the TM mode and TE mode light beams; this not only improves the utilization rate of the optical signal, but also provides the necessary polarization state control for the subsequent optical feedback process. The TE mode light beam is reflected back by a reflector and coupled into the VCSEL resonant cavity through optical feedback, thereby realizing the output of the square wave optical signal. In this process, the optical feedback distance can be adjusted as needed; by adjusting the external feedback cavity length, the resonance of the relaxation oscillation frequency of the TE mode light beam and the external cavity feedback frequency is realized. This resonance mechanism not only excites relaxation oscillations, but also realizes phase locking, thereby ensuring the stability and consistency of the square wave optical signal; through precise optical feedback control and phase locking mechanism, a high-quality square wave optical signal is successfully output. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0021] Figure 1 This is a structural diagram of a square wave optical signal source generation system according to an embodiment of the present invention; Figure 2 1 is the input-output curve of two linear polarization modes of the laser according to the embodiment of the present invention; Figure 3 This is the TE mode square wave time domain optical output of the embodiment of the present invention; Figure 4 The spectrum measured by the time-domain optical signal of the embodiment of the present invention; Figure 5 This is a block diagram of a method for generating a square wave optical signal source according to an embodiment of the present invention. DETAILED DESCRIPTION

[0022] In order to make the purpose, 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 in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. The components of the embodiments of the present invention described and marked in the drawings here can be arranged and designed in various different configurations.

[0023] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0024] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0025] In the description of the embodiments of the present invention, it should be noted that if the terms "upper", "lower", "horizontal", "inner", etc. indicate an orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of the invention is usually placed when in use, it is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first", "second", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0026] In addition, if the term "horizontal" appears, it does not mean that the component must be absolutely horizontal, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", which does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0027] In the description of the embodiments of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal connection of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0028] The present invention is further described in detail below in conjunction with the accompanying drawings: See also Figure 1 , the present invention provides a square wave optical signal source generation system, including a VCSEL laser, a polarization-maintaining beam splitter and a reflector; The light beam emitted by the VCSEL laser is divided into a TM mode light beam and a TE mode light beam by the polarization-maintaining beam splitter PBS; a reflector M is arranged on the propagation path of the TE mode light beam; the TE mode light beam is reflected by the reflector M and coupled into the resonant cavity of the VCSEL laser to realize the output of a square wave optical signal. A beam splitter BS is arranged between the polarization-maintaining beam splitter PBS and the VCSEL laser, and the beam splitter BS divides the light beam reflected by the VCSEL laser into two beams, one beam propagates to the polarization-maintaining beam splitter PBS, and the other beam is output through the optical isolator ISO. The beam splitter BS sets a 50:50 ratio beam splitting; the mode of the optical isolator ISO is the TE mode. A collimator L is arranged between the beam splitter BS and the VCSEL laser. A collimator L is arranged on the propagation path of the output beam of the optical isolator ISO, and the light beam is split by the beam splitter BS and passes through the optical isolator ISO and the collimator L in sequence before entering the photodetector.

[0029] The square wave optical signal source generation system provided by the present invention can accurately divide the laser beam into TM mode and TE mode by utilizing the combination of VCSEL (vertical cavity surface emitting laser) and polarization maintaining beam splitter (PBS). In particular, the TE mode light beam, after being reflected by the reflector M, is coupled back into the resonant cavity of the VCSEL laser, which not only enhances the feedback of the TE mode light, but also promotes the stable selection of the mode in the laser cavity, thereby realizing high-quality square wave optical signal output; significantly improving the stability and purity of the optical signal, which is particularly important for application scenarios that require precise control of the optical waveform. The optical splitter BS (ratio of 50:50) introduced in the system not only realizes the uniform distribution of the output beam of the VCSEL laser, but also guides one path to the PBS for mode separation and feedback, and the other path is output through the optical isolator ISO, effectively avoiding reflection interference in the optical path and improving the overall efficiency and stability of the system. The TE mode configuration of the optical isolator ISO ensures the mode consistency of the output light beam, further enhancing the performance of the system; the light beam split by the beam splitter BS passes through the optical isolator ISO and the collimator L, and finally enters the photodetector, providing a real-time monitoring channel for the system.

[0030] See also Figure 5 The present invention provides a method for generating a square wave optical signal source, comprising the following steps: S1, splitting the light beam emitted by the VCSEL laser to obtain a first light beam and a second light beam; The VCSEL laser is started, and the continuous light beam emitted by it is split by a beam splitter. The beam splitter is configured to evenly split the laser beam into two beams, which are marked as the first beam and the second beam respectively; the first beam is not directly used for the generation of the square wave optical signal in this embodiment, but can be used for system monitoring or other purposes. The second beam continues to the next step.

[0031] S2, performing polarization splitting on the second light beam to obtain a TM mode light beam and a TE mode light beam; The second beam then enters a polarization-maintaining beam splitter (PBS), which splits the light into a TM mode beam and a TE mode beam based on its polarization properties. The TM mode beam is strongly suppressed in a certain area. The TE mode beam is selected for the subsequent feedback process because it is the key to achieving a square wave optical signal.

[0032] S3, reflects the TE mode light beam back through the reflector, and couples it into the VCSEL resonant cavity through optical feedback to achieve square wave optical signal output.

[0033] The TE mode beam is reflected back through the reflector M, forming an external feedback loop. The position and angle of the reflector M are precisely adjusted to ensure that the TE mode beam can be efficiently recoupled into the resonant cavity of the VCSEL laser. In order to accurately control the feedback process, the external feedback cavity length is adjusted to match the relaxation oscillation frequency of the TE mode beam. It determines whether the external cavity feedback frequency and the relaxation oscillation frequency can resonate; when the two resonate, the optical feedback will excite the relaxation oscillation, and through the phase locking mechanism, the output of the laser will present a stable square wave characteristic.

[0034] The square wave optical signal generation method of the present invention efficiently separates the light beam emitted by the VCSEL laser into two independent light beams of TM mode and TE mode through beam splitting and polarization beam splitting steps. This polarization separation not only ensures the purity of the two mode light beams, but also provides a basis for subsequent polarization regulation; by setting a reflector in the propagation direction of the TE mode light beam, a feedback modulation loop is realized, and the interaction time between the light beam and the gain medium is increased, thereby improving the stability and output efficiency of the laser. At the same time, the design of the external ring cavity also helps to suppress the noise and fluctuation of the laser; an optical isolator is set on the detection optical path to achieve mode selection, thereby achieving fine regulation of the laser output; the components used in this method are relatively simple and easy to integrate, which provides a guarantee for the flexibility and scalability of the system. By adjusting the parameters of the external ring cavity, the rotation angle of the half-wave plate, etc., further regulation and optimization of the laser output can be achieved.

[0035] In order to further illustrate the advantages of the present invention, Figure 2The measured input-output curves of the two linear polarization modes of the laser in the embodiment of the present invention show that the threshold of the TE mode is much smaller than that of the TM mode. Specifically, the TE mode starts to output significant optical power at a lower input current, while the TM mode requires a higher input current to achieve the same output power level. This result verifies the low threshold characteristic of the TE mode in the VCSEL laser. The reason why the TE mode has a lower threshold is mainly because its light field distribution is more matched with the cavity structure of the VCSEL laser, resulting in more efficient energy conversion and lower light loss. In contrast, the light field distribution of the TM mode is not well matched with the cavity structure, so a higher input current is required to overcome the light loss and reach the threshold;.

[0036] Figure 3 This is the TE mode square wave time domain optical output of an embodiment of the present invention. Since the photodetector used is in AC form, it can be seen that the time domain optical signal oscillates around 0 with a period of 7 ns and an overall consistent amplitude, indicating that the square wave optical signal generated by the present invention has high reliability and consistency in the time domain.

[0037] Figure 4 The spectrum measured for the time-domain optical signal of the embodiment of the present invention has a center frequency of 7.6 GHz, which is the relaxation oscillation frequency of the square wave. Harmonics are distributed near the center frequency, and the harmonic spacing corresponds to the inverse of the feedback duration. It can be seen that the square wave optical signal generated by the present invention has good stability and good spectrum characteristics.

[0038] In summary, the present invention generates an initial light beam through a VCSEL laser, and uses a polarization-maintaining beam splitter to accurately divide the light beam into a TM mode and a TE mode. After the TE mode light beam is reflected by a reflector, it is coupled into the resonant cavity of the VCSEL laser again. This process enhances the optical feedback of the TE mode, thereby effectively generating a square wave optical signal. This design not only improves the efficiency of optical signal generation, but also ensures the stability and purity of the optical signal. An optical splitter is arranged between the VCSEL laser and the polarization-maintaining beam splitter to achieve precise control and distribution of the laser beam. The optical splitter divides the light beam into two beams at a ratio of 50:50, one beam is used to generate a square wave optical signal, and the other beam is output through an optical isolator for monitoring or other applications. This design not only improves the flexibility of the system, but also ensures the uniform distribution and effective use of the light beam. The collimator provided in the system helps to accurately calibrate and shape the light beam, ensuring the stability and consistency of the light beam during propagation. In addition, the use of an optical isolator effectively prevents reflection and interference of the optical signal, further improving the stability and reliability of the system. The optical isolator is designed as TE mode, which means that it only allows TE mode optical signals to pass through. This design helps to further purify the TE mode optical signal and reduce the interference of other mode optical signals, thereby improving the purity and quality of the square wave optical signal. A collimator is also set on the output beam propagation path of the optical isolator, which not only ensures the stability and consistency of the output beam, but also provides convenience for subsequent beam processing and application. In addition, the design and implementation of the system have high scalability and can be adjusted and optimized according to actual application requirements to meet the needs of different scenarios. At the same time, the components used in this method are relatively simple and easy to integrate, which provides a strong guarantee for the flexibility and scalability of the system. By adjusting the parameters of the external ring cavity, the rotation angle of the half-wave plate, etc., the laser output can be further regulated and optimized to meet the diverse needs of different application scenarios.

[0039] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A square wave optical signal source generation system, characterized in that: Includes VCSEL laser, polarization-maintaining beam splitter and reflector; The light beam emitted by the VCSEL laser is divided into a TM mode light beam and a TE mode light beam by a polarization-maintaining beam splitter; a reflector is arranged on the propagation path of the TE mode light beam; the TE mode light beam is reflected by the reflector and coupled into the resonant cavity of the VCSEL laser to realize the output of a square wave optical signal.

2. The square wave optical signal source generation system according to claim 1, characterized in that: A beam splitter is arranged between the polarization-maintaining beam splitter and the VCSEL laser. The beam splitter splits the light beam reflected by the VCSEL laser into two beams, one beam propagates to the polarization-maintaining beam splitter, and the other beam is output through the optical isolator.

3. The square wave optical signal source generation system according to claim 2, characterized in that: A collimator is arranged between the beam splitter and the VCSEL laser.

4. The square wave optical signal source generation system according to claim 2, characterized in that: The beam splitter splits the beam in a 50:50 ratio.

5. The square wave optical signal source generation system according to claim 1, characterized in that: The mode of the optical isolator is TE mode.

6. The square wave optical signal source generation system according to claim 1, characterized in that: A collimator is arranged on the propagation path of the output beam of the optical isolator.

7. A method for generating a square wave optical signal source, characterized in that: The following steps are involved: S1, splitting the light beam emitted by the VCSEL laser to obtain a first light beam and a second light beam; S2, performing polarization splitting on the second light beam to obtain a TM mode light beam and a TE mode light beam; S3, reflects the TE mode light beam back through the reflector, and couples it into the VCSEL resonant cavity through optical feedback to achieve square wave optical signal output.

8. The method for generating a square wave optical signal source according to claim 7, characterized in that: The optical feedback distance can be adjusted as required.

9. The method for generating a square wave optical signal source according to claim 7, characterized in that: The TE mode beam is reflected back through the reflector and coupled into the VCSEL resonant cavity through optical feedback to achieve square wave optical signal output, specifically: By adjusting the length of the external feedback cavity, the relaxation oscillation frequency of the TE mode light beam and the external cavity feedback frequency can be resonated. The relaxation oscillation can be excited by optical feedback and phase locking can be achieved, thereby realizing square wave signal output.

10. The method for generating a square wave optical signal source according to claim 9, characterized in that: By adjusting the optical feedback distance, the relaxation oscillation frequency of the TE mode light beam and the external cavity optical feedback frequency can achieve resonance.

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