Pulse shaping device and related equipment

Abstract

The embodiment of the invention provides a pulse shaping device and related equipment, which are used for improving time-frequency domain characteristics of ultrafast laser. The pulse shaping device provided by the embodiment of the invention comprises a first polarization controller, a first annular mirror assembly, a second polarization controller and a polarization analyzer. The first polarization controller is used for adjusting the polarization state of the pulse signal to obtain first polarized light and inputting the first polarized light into the first port of the first annular mirror assembly. The first annular mirror assembly comprises an optical coupler and a nonlinear medium, a first port and a second port of the optical coupler are connected with the first polarization controller and the second polarization controller respectively, and a third port and a fourth port of the optical coupler are connected with the two ends of the nonlinear medium respectively. The second polarization controller is used for connecting the second port and the polarization analyzer and adjusting the polarization state of the signal from the second port. And the polarization analyzer is used for carrying out polarization analysis on the signal from the second polarization controller and outputting a target pulse signal in a target polarization direction.

Description

Technical Field

[0001] The embodiments of the present application relate to the field of lasers, and in particular, to a pulse shaping device and related equipment. Background Art

[0002] Ultrafast lasers have an ultrashort pulse duration, an extremely high peak power, and a large spectral bandwidth, so they are widely used in fields such as advanced manufacturing, optical sensing, and medical treatment, and also have good application prospects in the field of optical communication. However, in practical applications, the system has high requirements for parameters such as the temporal pulse width, spectral bandwidth, and flatness of the ultrafast laser source (time-frequency domain characteristics), and it is necessary to perform pulse shaping on the ultrafast laser source to improve the time-frequency domain characteristics of the ultrafast laser source.

[0003] The currently commonly used pulse shaping method is a spatial optical shaping system. The spatial optical shaping system uses a 4F structure to perform pulse shaping on the laser pulse through the time-frequency space mapping of Fourier transform, that is, to realize the modulation of the amplitude, phase, polarization, etc. of the ultrafast laser.

[0004] However, the spatial optical shaping system includes multiple optical transformation elements (such as gratings, modulators, etc.), which not only have high device costs, but also result in large system insertion losses, and subsequent optical modulation with a large dynamic range will affect the optical signal-to-noise ratio. Moreover, the 4F structure of the spatial optical shaping system has high requirements for the position accuracy of the devices. Once the positions of the devices in the system change due to reasons such as vibration, it will affect the pulse shaping effect and result in poor system robustness. Summary of the Invention

[0005] The embodiments of the present application provide a pulse shaping device and related equipment for improving the time-frequency domain characteristics of ultrafast lasers, having low insertion loss and high robustness characteristics.

[0006] In a first aspect, the embodiments of the present application provide a pulse shaping device. The pulse shaping device includes a first polarization controller, a first ring mirror assembly, a second polarization controller, and a polarization analyzer. The first polarization controller is used to adjust the polarization state of the pulse signal to obtain a first polarized light, and input the first polarized light into the first port of the first ring mirror assembly. The first polarized light includes linearly polarized light, elliptically polarized light, or circularly polarized light. The first ring mirror assembly includes an optical coupler and a nonlinear medium. The first port and the second port of the optical coupler are respectively connected to the first polarization controller and the second polarization controller, and the third port and the fourth port are respectively connected to both ends of the nonlinear medium. The second polarization controller is used to connect the second port to the polarization analyzer and adjust the polarization state of the signal from the second port. The polarization analyzer is used to perform polarization analysis on the signal from the second polarization controller and output a target pulse signal in a target polarization direction.

[0007] In the embodiments of the present application, the first annular mirror assembly can shape the pulse signal based on the nonlinear effect. The first polarization controller, the nonlinear medium, the second polarization controller, and the polarization analyzer form a nonlinear polarization rotation (NPR) structure, and the NPR structure can shape the pulse signal based on the nonlinear birefringence effect. Through the structure provided by the embodiments of the present application, two effects (the nonlinear effect in the first annular mirror assembly and the nonlinear birefringence effect in the NPR structure) are realized on the same nonlinear annular mirror (the first annular mirror assembly), and the pulse shaping effects of the two effects enhance each other, so the pulse shaping effect is good. Moreover, integrating the two effects on one nonlinear annular mirror (the first annular mirror assembly) can improve the system integration degree and reduce the system complexity. This structure is different from the optical shaping system, and the components in the fiber connection structure can be connected by optical fibers, so the structure stability is higher.

[0008] Moreover, since the two effects are realized on the same nonlinear annular mirror, the effects of the two effects are superimposed on each other (and will not weaken each other), so the shaping effect is better than the simple series connection of the two structures.

[0009] In the embodiments of the present application, the nonlinear effect in the first annular mirror assembly includes but is not limited to self-phase modulation and cross-phase modulation.

[0010] In the embodiments of the present application, the first polarized light obtained by the first polarization controller is the polarized light matching the first annular mirror assembly. The first polarized light matching the first annular mirror assembly means that the polarization state of the first polarized light entering the nonlinear medium through the third port and then transmitted to the fourth port is the same as the polarization state of the first polarized light entering the nonlinear medium through the fourth port and then transmitted to the third port.

[0011] In an optional implementation manner, the first annular mirror assembly is a nonlinear optical loop mirror (NOLM), and the coupling efficiencies at both ends of the nonlinear medium are different.

[0012] In the embodiments of the present application, the structure of the NOLM can compress the pulse width, suppress the pulse side lobes, increase the spectral bandwidth, improve the spectral flatness, and introduce the nonlinear polarization rotation effect at the same time.

[0013] In an optional implementation manner, the first annular mirror assembly is a nonlinearly amplifying loop mirror (NALM), and the NALM includes an optical coupler, a nonlinear medium, and an optical amplifier. The optical coupler and the nonlinear medium form a loop, and the amplifier is in this loop.

[0014] In the embodiments of the present application, the optical amplifier in the NALM can amplify the pulse signal in the loop. The increase in signal intensity not only reduces the loss of the ring mirror assembly, but also enhances the nonlinear phase shift and nonlinear birefringence effect in the loop, thereby improving the pulse shaping effect and enhancing the polarization rotation effect.

[0015] In an alternative implementation, the optical amplifier is between the third port and the nonlinear medium, or between the fourth port and the nonlinear medium.

[0016] In the embodiments of the present application, between the third port and the nonlinear medium, and between the fourth port and the nonlinear medium, are independent of each other and require specific processes for connection. By setting the optical amplifier between the third port and the nonlinear medium or between the fourth port and the nonlinear medium, since the ports and the nonlinear medium are originally independent of each other, the optical amplifier can be directly connected between the port and the nonlinear medium without disconnecting the port or the nonlinear medium to connect the optical amplifier, and the operation is simple and convenient.

[0017] In an alternative implementation, the third port and the fourth port are optical fibers.

[0018] In an alternative implementation, the nonlinear medium includes a first medium, the third port and the fourth port are a second medium, and the nonlinear coefficient of the first medium is higher than that of the second medium.

[0019] In the embodiments of the present application, through the nonlinear medium with a higher nonlinear coefficient, a larger nonlinear phase shift and nonlinear birefringence effect can be achieved within a unit optical path, improving the efficiency of pulse shaping, and thus improving the pulse shaping effect.

[0020] In an alternative implementation, the nonlinear medium includes an optical chip and / or a nonlinear optical fiber. The optical chip includes at least one of the following materials: silica, silicon nitride, tantalum oxide, or lithium niobate.

[0021] In the embodiments of the present application, if the nonlinear medium includes an optical chip, the optical chip has a small volume and a high nonlinear coefficient, which can improve the integration level and pulse shaping effect of the pulse shaping device. If the nonlinear medium includes a nonlinear optical fiber, since the preparation of the nonlinear optical fiber is relatively mature and the connection process between the nonlinear optical fiber and the third port and the fourth port is simple, the cost of the pulse shaping device can be reduced.

[0022] In an alternative implementation, it further includes a second ring mirror assembly, and the second ring mirror assembly is located between the first ring mirror assembly and the second polarization controller. Optionally, the second ring mirror assembly can be a NOLM or a NALM.

[0023] In the embodiments of the present application, the NOLM cavity / NALM cavity is connected in series with the second ring mirror assembly to perform pulse shaping on the signal, thereby further improving the effect of pulse shaping.

[0024] In an alternative implementation, a third polarization controller is further included. The third polarization controller is located between the first ring mirror assembly and the second ring mirror assembly and is used to adjust the polarization state of the pulse signal from the first ring mirror assembly.

[0025] In the embodiments of the present application, through the adjustment of the third polarization controller, the polarization state of the pulse signal entering the second ring mirror assembly is matched with the second ring mirror assembly, and a better pulse shaping effect can be achieved.

[0026] The second ring mirror assembly has the same structure as the first ring mirror assembly. The polarization light matching the second ring mirror assembly means that in the second ring mirror assembly, the polarization state of the polarization light entering the nonlinear medium through the third port and transmitted to the fourth port is the same as the polarization state of the first polarization light entering the nonlinear medium through the fourth port and transmitted to the third port.

[0027] In an alternative implementation, the polarization analyzer is a polarization beam splitter. The polarization beam splitter includes two output ports, which are respectively used to output the first target pulse signal in the first polarization direction and the second target pulse signal in the second polarization direction, and the first polarization direction is perpendicular to the second polarization direction.

[0028] In the embodiments of the present application, the polarization beam splitter is used to split the two pulse signals with different polarization directions, so that the two different signals are carried by the orthogonally linearly polarized light in the pulse shaping device, and the two signals can have different applications. For example, in a communication scenario, the two signals can be used as the light source pool of the communication device, the port for detecting the light source state, and the coherent light source; in a detection scenario, the two signals can be used as the multi-channel detection light source. By using the two split signals, the utilization rate of the optical power can be improved.

[0029] In an alternative implementation, the polarization analyzer is a polarizer.

[0030] In the embodiments of the present application, due to the direction selection characteristic of the linearly polarized light of the polarizer, the linearly polarized pulse light with a flat spectrum and a narrow pulse width can be selectively transmitted by adjusting the second polarization controller.

[0031] In an alternative implementation, the second polarization controller is used to obtain orthogonally linearly polarized light (i.e., two beams of polarized light with perpendicular polarization directions). The polarization directions of the signals output by the second polarization controller are the same as the polarization directions of the beams that can pass through the polarization beam splitter, which are the P-light direction and the S-light direction of the polarization beam splitter.

[0032] In an alternative implementation, an optical amplifier is further included. The optical amplifier is used to amplify the input pulse signal of the pulse shaping device and input the amplified signal into the first polarization controller.

[0033] In the embodiments of the present application, the optical amplifier can increase the peak power of the pulse, so that the ring mirror module introduces sufficient non - linear phase shift and non - linear polarization rotation effect, thereby realizing pulse shaping.

[0034] In an alternative implementation, an optical filter is further included. The optical filter is located between the optical amplifier and the first polarization controller and is used to filter out the spontaneous emission noise of the optical amplifier.

[0035] In the embodiments of the present application, adding an optical filter between the optical amplifier and the first polarization controller can filter out the noise brought by the optical amplifier, thereby improving the signal - to - noise ratio of the system.

[0036] In a second aspect, the embodiments of the present application further provide a pulsed laser. The laser includes a seed pulse light source and the pulse shaping device described in the first aspect. The seed pulse light source is used to emit a pulse signal, and the pulse shaping device is used to shape the pulse signal.

[0037] In an alternative implementation, the seed pulse light source includes any one of the following:

[0038] An electro - optical comb light source, a solid - state laser light source, a fiber laser light source or a semiconductor laser light source.

[0039] Optionally, the pulse width of the pulse signal can be at the picosecond or femtosecond level, and the present application does not make any limitation thereto.

[0040] In a third aspect, the embodiments of the present application further provide a detection system. The detection system includes the pulsed laser described in the second aspect and a detector. The pulsed laser is used to emit pulsed laser, and the detector is used to detect the pulsed laser passing through the substance to be measured.

[0041] In a fourth aspect, the embodiments of the present application further provide an optical communication device. The optical communication device includes the pulsed laser, a demultiplexer and a modulator described in the second aspect. The pulsed laser is used to emit pulsed laser, and the longitudinal modes of the laser with different frequencies in the pulsed laser are used to carry different channels of signals. The demultiplexer is used to demultiplex the pulsed laser based on frequency. The modulator is used to modulate the demultiplexed pulsed laser.

[0042] In a fifth aspect, the embodiments of the present application further provide an optical communication device. The optical communication device includes the pulsed laser and a photodetector described in the second aspect. The pulsed laser is used to emit pulsed laser. The photodetector is used to receive the optical signal and use the pulsed laser as a coherent light source to realize the detection of the optical signal.

[0043] In a sixth aspect, an embodiment of the present application further provides a laser processing system. The laser processing system includes the pulsed laser and the optical path structure described in the second aspect. The pulsed laser is used to emit high-intensity pulsed laser light. The optical path structure is used to focus the pulsed laser light on the processing point, and the workpiece is processed by the pulsed laser light.

[0044] For the beneficial effects of the second aspect to the sixth aspect, please refer to the first aspect, which will not be elaborated here. Description of the Drawings

[0045] Figure 1 It is a schematic structural diagram of the optical shaping system provided by the present application;

[0046] Figure 2 It is a schematic structural diagram of the pulse shaping device provided by an embodiment of the present application;

[0047] Figure 3 It is a schematic structural diagram of the NOLM provided by an embodiment of the present application;

[0048] Figure 4 It is a schematic structural diagram of the NALM provided by an embodiment of the present application;

[0049] Figure 5 It is a schematic structural diagram of the ring mirror assembly with the optical chip as the nonlinear medium provided by an embodiment of the present application;

[0050] Figure 6 It is a schematic structural diagram of the pulse shaping device including the second ring mirror assembly provided by an embodiment of the present application;

[0051] Figure 7 It is a schematic structural diagram of the polarization beam splitter provided by an embodiment of the present application;

[0052] Figure 8 It is a schematic structural diagram of a pulsed laser provided by an embodiment of the present application;

[0053] Figure 9 It is another schematic structural diagram of a pulsed laser provided by an embodiment of the present application;

[0054] Figure 10 It is a schematic structural diagram of the detection system provided by an embodiment of the present application;

[0055] Figure 11 It is a schematic structural diagram of an optical communication device provided by an embodiment of the present application;

[0056] Figure 12 It is another schematic structural diagram of an optical communication device provided by an embodiment of the present application;

[0057] Figure 13Schematic structural diagram of the laser processing system provided by the embodiment of the present application;

[0058] Figure 14 Result diagram of the time-frequency domain characteristics of the electro-optic comb pulse provided by the embodiment of the present application;

[0059] Figure 15 Spectrum diagram of the electro-optic comb pulse provided by the embodiment of the present application;

[0060] Figure 16 Spectrum diagram of the input port and two output ports of the polarization analyzer provided by the embodiment of the present application. Detailed implementation manners

[0061] The embodiments of the present application will be described below with reference to the accompanying drawings. As can be known to those of ordinary skill in the art, with the development of technology and the emergence of new scenarios, the technical solutions provided by the embodiments of the present application are also applicable to similar technical problems.

[0062] Terms such as "first" and "second" in the specification, claims and above-mentioned drawings of the present application are used to distinguish similar objects, and do not have to be used to describe a specific order or sequence. It should be understood that such terms can be interchanged under appropriate circumstances, which is only a way of distinguishing when describing objects with the same attributes in the embodiments of the present application. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion, so that a process, method, system, product or device including a series of units does not have to be limited to those units, but may include other units not clearly listed or inherent to these processes, methods, products or devices. In addition, "at least one" means one or more, and "a plurality" means two or more. "And / or" describes the association relationship of associated objects, indicating that three relationships can exist. For example, A and / or B can mean: A exists alone, A and B exist simultaneously, and B exists alone, where A and B can be singular or plural. The character " / " generally means that the associated objects before and after are in an "or" relationship. "At least one (item)" or similar expressions thereof refer to any combination of these items, including any combination of single item (item) or plural items (items). For example, at least one (item) of a, b, or c can mean: a, b, c, a - b, a - c, b - c, or a - b - c, where a, b, c can be single or multiple.

[0063] With the development of laser technology, laser light sources have gradually been popularized from laboratory research to application fields such as optical communication, advanced manufacturing, optical sensing, and medical treatment. Pulsed laser is a type of laser. Pulsed laser has a short pulse width, high peak power, and wide spectral bandwidth, and is widely used in fields such as precision machining, optical sensing, medical treatment, and spectral analysis, and also has good application prospects in the field of optical communication.

[0064] However, in practical applications, the system has certain requirements for parameters such as the time-domain pulse width, spectral bandwidth, and flatness of the laser light source (time-frequency domain characteristics), and it is necessary to perform pulse shaping on the laser light source to improve the time-frequency domain characteristics of the laser light source.

[0065] The currently commonly used pulse shaping method is a spatial optical shaping system. As Figure 1 shown, the spatial optical shaping system uses a 4F system to perform pulse shaping on the laser pulse through the time-frequency space mapping of Fourier transform, that is, the modulation of the amplitude, phase, polarization, etc. of the laser.

[0066] However, the spatial optical shaping system includes multiple optical transformation elements (such as gratings, modulators, etc.), which not only have high device costs but also result in large system insertion losses. Subsequent optical modulation with a large dynamic range will affect the optical signal-to-noise ratio. Moreover, the 4F system of the spatial optical shaping system has high requirements for the position accuracy of the devices. Once the positions of the devices in the system change due to reasons such as vibration, it will affect the pulse shaping effect and result in poor system robustness. Among them, poor robustness can be specifically manifested as waveform distortion, poor spectral reduction, and deterioration of bandwidth flatness.

[0067] To solve the above problems, the embodiments of the present application provide a pulse shaping device and related equipment. The pulse shaping device provided by the embodiments of the present application forms an annular mirror assembly and a non-linear polarization rotation structure through the same section of non-linear medium, realizing the coupling of non-linear effects and non-linear birefringence effects in the same ring. This structure has good shaping effects, low system insertion losses, and high robustness.

[0068] As Figure 2 shown, the pulse shaping device 2000 provided by the embodiments of the present application includes a first polarization controller 2100, a first annular mirror assembly 2200, a second polarization controller 2300, and an analyzer device 2400. Among them, the first polarization controller 2100 is used to adjust the polarization state of the pulse signal to obtain a first polarized light. The first polarized light includes linearly polarized light, elliptically polarized light, or circularly polarized light. The first polarized light is input into the first annular mirror assembly 2200 through the first port 2211 of the first annular mirror assembly 2200.

[0069] The first annular mirror assembly 2200 includes an optical coupler 2210 and a non-linear medium 2220. The optical coupler 2210 includes four ports. As Figure 3 shown, the first port 2211 and the second port 2212 are respectively connected to the first polarization controller 2100 and the second polarization controller 2300, and the third port 2213 and the fourth port 2214 are respectively connected to both ends of the non-linear medium 2220.

[0070] The nonlinear medium 2220 and the optical coupler 2210 in the first annular mirror assembly 2200 form a loop. When a pulse signal is transmitted in this loop, a nonlinear effect will be generated, and the transmittance of the loop is related to the magnitude of the nonlinear phase shift. Different intensity distributions of the pulse signal in the time domain will cause different nonlinear phase shifts in the loop. The power at the center (peak part) of the pulse signal is high, and the nonlinear phase shift is large, resulting in a high transmittance of the pulse center in the loop, so that it can pass through the output port. The power of the two edges and side lobes of the pulse signal is low, and the nonlinear phase shift is small, resulting in a low transmittance of the pulse edges and side lobes in the loop, and they will return in the form of reflected light.

[0071] As described above, the loop has different transmittances for signals with different intensities. Therefore, the first annular mirror assembly 2200 can be used to compress the pulse width and suppress the side lobes of the pulse signal. The suppression of the side lobes can reduce the interference between the side lobes and the main peak, thereby improving the flatness of the pulse spectrum. Moreover, the nonlinear effects generated by the pulse signal in the nonlinear medium 2220 include self-phase modulation and cross-phase modulation, and the self-phase modulation and cross-phase modulation can broaden the spectral bandwidth of the pulse signal.

[0072] When the pulse signal is transmitted in the nonlinear medium 2220, due to the nonlinear effect, the refractive indices are different in different directions perpendicular to the signal transmission direction, forming a nonlinear birefringence effect. The nonlinear birefringence effect causes different degrees of polarization angle changes in the parts of the pulse signal with different pulse intensities. Since the rotation angle of the polarization direction is related to the pulse intensity, the polarization states at different positions of the pulse are rotated and different, that is, the time-domain distribution of the pulse signal has different polarization state distributions.

[0073] In the embodiment of the present application, the first polarized light obtained by the first polarization controller 2100 is polarized light that matches the first annular mirror assembly 2200. The first polarized light matching the first annular mirror assembly 2200 means that the polarization state of the first polarized light entering the nonlinear medium 2220 through the third port 2213 and transmitted to the fourth port 2214 is the same as the polarization state of the first polarized light entering the nonlinear medium 2220 through the fourth port 2214 and transmitted to the third port 2213.

[0074] The second polarization controller 2300 is used to connect the second port 2212 (of the optical coupler 2210) to the polarization analyzer 2400 and adjust the polarization state of the signal from the second port 2212. The polarization analyzer 2400 is used to analyze the polarization of the signal from the second polarization controller and output the target pulse signal in the target polarization direction.

[0075] Among them, the polarization analyzer 2400 is used to allow signals with a specific polarization direction (such as the target polarization direction) to pass through. Due to the nonlinear birefringence effect of the pulse signal in the nonlinear medium 2220, signals with different pulse intensities have different polarization directions. The second polarization controller 2300 is used to adjust the polarization direction of the pulse signal, and adjust the peak part of the pulse signal to the polarization direction of the polarization analyzer 2400, so that the peak part of the pulse signal can pass through the polarization analyzer 2400.

[0076] In an alternative implementation, the second polarization controller 2300 is used to obtain orthogonally linearly polarized light (i.e., two beams of polarized light with mutually perpendicular polarization directions). The polarization direction of the signal output by the second polarization controller 2300 is consistent with the polarization direction of the beam that can pass through the polarization analyzer 2400, which is the P-light direction and the S-light direction of the polarization analyzer.

[0077] In the embodiment of the present application, a nonlinear polarization rotation (NPR) structure is formed by the first polarization controller 2100, the nonlinear medium 2220, the second polarization controller 2300, and the polarization analyzer 2400. By utilizing the nonlinear birefringence effect of the pulse signal in the nonlinear medium, the screening of the high-intensity signal at the center of the pulse is realized based on the polarization direction, thereby compressing the pulse time domain width and realizing ultrashort pulse shaping.

[0078] In the embodiment of the present application, the first annular mirror assembly 2200 can realize the shaping of the pulse signal based on the nonlinear effect. The first polarization controller 2100, the nonlinear medium 2220, the second polarization controller 2300, and the polarization analyzer 2400 form a nonlinear polarization rotation NPR structure, and the NPR structure can realize the shaping of the pulse signal based on the nonlinear birefringence effect. Through the structure provided by the embodiment of the present application, two effects are realized on the same nonlinear annular mirror (the first annular mirror assembly 2200), and the pulse shaping effects of the two effects enhance each other, so the pulse shaping effect is good. Moreover, integrating the two effects on a single nonlinear annular mirror (the first annular mirror assembly 2200) can improve the system integration degree and reduce the system complexity. This structure is different from the optical shaping system, and each component in the fiber connection structure can be connected by optical fibers, so the structure stability is higher.

[0079] Furthermore, since the two effects are realized on the same nonlinear annular mirror, the effects of the two effects are superimposed on each other (and will not weaken each other), so the shaping effect is better than the simple series connection of the two structures.

[0080] In the embodiments of the present application, the first ring mirror assembly 2200 may be a nonlinear optical loop mirror (NOLM), a non-linear amplifying loop mirror (NALM), etc.

[0081] If the first ring mirror assembly 2200 is a nonlinear optical loop mirror NOLM, the specific structure is as Figure 3 shown. The coupling efficiencies at both ends of the nonlinear medium 2220 are different, that is, the coupling efficiencies of the third port 2213 and the fourth port 2214 are different.

[0082] For example Figure 3 as shown, if the splitting ratio of the third port 2213 and the fourth port 2214 is a: 1-a, then a is not 0.5. In one example, the splitting ratio between the third port 2213 and the fourth port 2214 is 4:6, 3:7 or 2:8, and vice versa. The present application does not limit this.

[0083] If the first ring mirror assembly 2200 is a non-linear amplifying loop mirror NALM, then as Figure 4 shown, the first ring mirror assembly 2200 includes an optical coupler 2210, a nonlinear medium 2220, and an optical amplifier 2230. The optical coupler 2210 and the nonlinear medium 2220 form a loop, and the optical amplifier 2230 is in this loop.

[0084] For example Figure 4 as shown, the optical amplifier 2230 is located between the third port 2113 and the nonlinear medium 2220. Optionally, the optical amplifier 2230 may also be located between the fourth port 2114 and the nonlinear medium 2220, or on the third port 2213, the fourth port 2214, or the nonlinear medium 2220. For example, if the nonlinear medium 2220 is a highly nonlinear optical fiber, the nonlinear medium 2220 can be cut into two sections, and the optical amplifier 2230 is connected at the cut.

[0085] In the embodiments of the present application, the third port 2113 and the fourth port 2114 may be optical fibers, and the nonlinear medium 2220 may be an optical fiber, an optical chip, etc. The present application does not limit this.

[0086] In an optional implementation manner, the nonlinear medium 2200 includes a first medium, the third port 2113 and the fourth port 2114 are second media, and the nonlinear coefficient of the first medium is higher than that of the second medium. For example, the second medium is an ordinary single-mode optical fiber, and the first medium is a highly nonlinear optical fiber (the nonlinear coefficient of the first medium is one order of magnitude higher than that of the second medium. For example, the core of the first medium is smaller, the mode field area is smaller, and the nonlinear refractive index is larger).

[0087] In an alternative implementation, if the nonlinear medium 2220 is an optical chip (such as Figure 5 shown), the nonlinear medium 2200 may include materials such as silicon dioxide, silicon nitride, tantalum oxide, lithium niobate, etc. The third port 2113 and the fourth port 2114 are respectively connected to waveguides in the optical chip.

[0088] In the embodiments of the present application, the annular mirror assembly and the NPR structure are coupled through the nonlinear medium 2200. To achieve a better pulse shaping effect, more annular mirror assemblies can also be connected in series in the device. For example Figure 6 shown, between the first annular mirror assembly 2200 and the second polarization controller 2300, a second annular mirror assembly 2500 may also be included.

[0089] In the embodiments of the present application, when the second annular mirror assembly 2500 is connected in series behind the first annular mirror assembly 2200, the connected annular mirror assembly structure can again achieve an enhanced effect of pulse shaping through the nonlinear transmittance effect.

[0090] Optionally, as Figure 6 shown, between the first annular mirror assembly 2200 and the second annular mirror assembly 2500, a third polarization controller 2600 may also be added. The third polarization controller 2600 is used to adjust the polarization state of the signal from the first annular mirror assembly 2200 so that the polarization state of the pulse signal input to the second annular mirror assembly 2500 matches that of the second annular mirror assembly 2500.

[0091] In the embodiments of the present application, by adjusting the polarization state of the signal input to the second annular mirror assembly 2500 through the third polarization controller 2600 so that the polarization state of the signal input to the second annular mirror assembly 2500 matches that of the second annular mirror assembly 2500, a better pulse shaping effect can be achieved.

[0092] In the embodiments of the present application, the polarization analyzer 2400 may be a polarization beam splitter, a polarizer, etc., and the present application does not limit this.

[0093] If the polarization analyzer 2400 is a polarization beam splitter, the corresponding structure is as Figure 7 shown. The polarization beam splitter includes two output ports, which are respectively used to output a first target pulse signal in a first polarization direction and a second target pulse signal in a second polarization direction. Among them, the first polarization direction and the second polarization direction are perpendicular to each other.

[0094] Optionally, in the pulse signal of the input pulse shaping device 2000, the first pulse signal and the second pulse signal with perpendicular polarization directions can be modulated. Then, the first target pulse signal is the signal obtained after being shaped by the pulse shaping device 2000, and the second target pulse signal is the signal obtained after being shaped by the pulse shaping device 2000. Thus, two different signals are carried by the same path of pulse signal in the pulse shaping device 2000, and different paths of signals are output through different output ports of the polarization beam splitter.

[0095] In the embodiments of the present application, the polarization beam splitter is used to split two pulse signals with different polarization directions, so that two different signals are carried by the same path of pulse signal in the pulse shaping device 2000, which can improve the bandwidth of the pulse shaping device 2000 and the system (such as an optical communication system, a detection system, etc.) including the pulse shaping device.

[0096] Optionally, the pulse signal input to the pulse shaping device 2000 may also only include one path of pulse signal. Then, one output port of the polarization beam splitter can be truncated, and the pulse signal shaped by the pulse shaping device 2000 is transmitted through the other output port.

[0097] Optionally, in order to improve the shaping effect of the pulse shaping device 2000, an optical amplifier can also be added before the first polarization controller 2100. The optical amplifier is used to amplify the power of the pulse signal input to the first polarization controller 2100 and introduce sufficient nonlinear phase shift so that optical coherent superposition achieves the pulse shaping effect.

[0098] Optionally, an optical filter can also be added between the optical amplifier and the first polarization controller 2100 to filter out the noise brought by the amplifier, thereby improving the optical signal-to-noise ratio of the system. Optionally, the optical filter can be a diffraction-type optical filter, an interference-type optical filter, a prism-type optical filter, etc., and the embodiments of the present application do not limit this.

[0099] The embodiments of the present application also provide a pulse laser, which includes a seed pulse light source and the pulse shaping device 2000 described in the foregoing embodiments. Among them, the seed pulse light source is used to emit a pulse signal, and the pulse shaping device 2000 is used to shape the pulse signal. The structure of the pulse laser provided by the embodiments of the present application can be as Figure 8 and Figure 9 shown.

[0100] As Figure 8 shown, module 1 is a light source module, that is, the aforementioned seed pulse light source. Module 2 is a preprocessing module, module 3 is a ring mirror module (i.e., the aforementioned first ring mirror assembly 2200), and module 4 is an analyzer module. Module 2, module 3, and module 4 constitute the aforementioned pulse shaping device 2000.

[0101] Among them, the light source module 1 includes a continuous laser 11, an intensity modulator 12, and N phase modulators 13. The continuous laser 11 outputs single-frequency continuous light and sequentially enters the intensity modulator 12 and the N phase modulators 13. The front and rear positions of the intensity modulator 12 and the phase modulator 13 can be interchanged. The radio frequency signal source 15 emits a sinusoidal electrical signal carrying the target frequency and power.

[0102] This process enables the continuous laser to form pulsed laser in the time domain. The repetition frequency of the pulse depends on the electrical signal frequency; in the frequency domain, new frequency sidebands will appear at both ends of the initial optical frequency. The interval between the sidebands and the initial frequency is the loaded electrical signal frequency, thus forming an electro-optically modulated optical frequency comb (abbreviated as electro-optic comb). Among them, the center wavelength is defined by the continuous laser 11, and the repetition frequency of the electro-optic comb pulses is controlled by the output frequency of the radio frequency signal source 15, and both can be flexibly adjusted. Subsequently, pulse compression is performed through a pre-calculated dispersion compensator 14 (such as a single-mode fiber, a fiber grating, a spatial optical shaper), which enables the electro-optic comb to output ultra-short optical pulses with a picosecond-level pulse width.

[0103] The preprocessing module 2 includes an optical fiber amplifier 21, an optical fiber filter 22, and a polarization controller 23. The optical fiber amplifier 21 is used to amplify the average power of the electro-optic comb to meet the power requirements for pulse shaping. The optical fiber filter 22 is used to filter out the optical noise introduced by the optical fiber amplifier 21 and improve the optical signal-to-noise ratio of the pulse. The polarization controller 23 is used to adjust the polarization state of the input module 3.

[0104] Module 3 is a loop mirror module, including an optical fiber coupler 31 and a highly nonlinear optical fiber 32. Module 3, the optical fiber coupler 31, and the highly nonlinear optical fiber 32 respectively correspond to the first loop mirror assembly 2200, the optical coupler 2210, and the nonlinear medium 2220 in the foregoing embodiment. For the specific connection structure and functions, etc., refer to the description of the foregoing embodiment, and details are not described herein again.

[0105] The polarization analyzer module 4 includes a polarization controller 41 and a polarizing beamsplitter (PBS) 42. The polarization controller 41 and the polarizing beamsplitter 42 respectively correspond to the second polarization controller 2300 and the polarization analyzing device 2400 in the foregoing embodiment. For the specific connection structure and functions, etc., refer to the description of the foregoing embodiment, and details are not described herein again.

[0106] As Figure 9 shown, the pulsed laser 16 is a front-end light source, including but not limited to a solid-state laser, an optical fiber laser, a microcavity laser, a semiconductor laser, etc. The output pulsed laser is incident on the pulse shaping device 2000 provided in the embodiment of the present application (i.e., Figure 9Modules 2, 3, and 4). The pulsed laser 16 is the aforementioned seed pulsed light source. For the descriptions of Modules 2, 3, and 4, see Figure 8 the description of the foregoing embodiments, which will not be elaborated herein.

[0107] Optionally, the pulse width of the pulse signal can be at the picosecond or femtosecond level, and this application does not limit it.

[0108] The embodiment of this application also provides a detection system, which includes the aforementioned pulsed laser and detector. As Figure 10 shown, the pulsed laser is used to emit pulsed laser, and the pulsed laser is received by the detector after passing through the substance to be measured. The detector is used to detect the pulsed laser passing through the substance to be measured.

[0109] Optionally, the substance to be measured can be gas, liquid, solid, etc., and this application does not limit it. The wavelength at the signal spectrum depression can be determined through the signal detected by the detector, so as to determine the wavelength of the light signal absorbed by the substance to be measured and determine the composition of the substance to be measured.

[0110] The embodiment of this application also provides an optical communication device, which includes the aforementioned pulsed laser, optical demultiplexer, and modulator. As Figure 11 shown, the pulsed laser is used to emit pulsed laser, the optical demultiplexer is used to demultiplex the pulsed laser based on wavelength, and the modulator is used to modulate the demultiplexed pulsed laser.

[0111] The embodiment of this application also provides an optical communication device, which includes the aforementioned pulsed laser and optical detector. As Figure 12 shown, the pulsed laser is used to emit pulsed laser. The optical detector is used to receive the optical signal and use the pulsed laser as a coherent light source to realize the detection of the optical signal.

[0112] In an optional implementation manner, Figure 12 the optical communication device further includes a first optical demultiplexer and a second optical demultiplexer. The first optical demultiplexer is used to demultiplex the pulsed laser from the laser based on wavelength, and the second optical demultiplexer is used to demultiplex the optical signal based on wavelength. The detector includes optical detectors of each wavelength. The demultiplexed pulsed laser is transmitted to the optical detector corresponding to the wavelength, and the optical signal of the same wavelength is also transmitted to this optical detector. This optical detector realizes the coherent detection of the optical signal of this wavelength through the pulsed laser of this wavelength.

[0113] The embodiment of this application also provides a laser processing system, which includes the aforementioned pulsed laser and optical path structure. As Figure 13 shown, the pulsed laser is used to emit high-intensity pulsed laser. The optical path structure is used to focus the pulsed laser on the processing point and realize the processing of the workpiece through the pulsed laser.

[0114] Optionally, the laser provided in the embodiments of the present application may also be applied to medical devices, precision measuring equipment, astronomical instruments, optical storage instruments and other equipment, and the present application does not limit this.

[0115] The structures of the pulse shaping device 2000 and related devices provided in the embodiment of the present application are described above. The adjustment method of each polarization controller in the pulse shaping device 2000 is described below. Figure 2 The structure shown is used as an example for explanation.

[0116] First, adjust the first polarization controller 2100 to obtain Figure 14 The time-frequency domain characteristics of the electro-optic comb pulse are shown in the figure. Figure 14 In the figure, the solid line indicates that the first annular mirror assembly 2200 ( Figure 14 The dotted line represents the time-frequency domain characteristics of the pulse signal after passing through the first annular mirror assembly 2200. Figure 14 As shown, the first loop mirror assembly 2200 broadens the spectrum. By continuously adjusting the first polarization controller 2100 to obtain the widest spectrum, the adjustment of the first polarization controller 2100 is completed.

[0117] Then, adjust the second polarization controller 2300 to obtain Figure 15 The electro-optic comb pulse spectrum is shown in Figure 2. Figure 15 In the figure, the solid line indicates the polarization without the polarization analyzer 2400 ( Figure 15 The time-frequency domain characteristics of the pulse signal before the polarization detector 2400 are shown in FIG. 2 and the dotted line shows the time-frequency domain characteristics of the pulse signal after the polarization detector 2400 is passed through. Figure 15 As shown, the spectral flatness of the pulse is improved after passing through the polarization analyzer 2400. By continuously adjusting the second polarization controller 2300 to obtain the spectrum with the best flatness, the adjustment of the second polarization controller 2300 is completed. After adjusting the second polarization controller 2300, the polarization analyzer 2400 reduces the spectral flatness of the pulse center area from the original 10dB to 5dB.

[0118] Figure 16 For the polarization analyzer device 2400 ( Figure 15 The spectrum diagram of the input port and two output ports of the device (denoted by PBS in the figure). Figure 16 As shown, after adjusting the second polarization controller 2300, the NPR structure optimizes the flatness of the spectrum from 35nm spectrum bandwidth at 14dB spectrum flatness to 32nm spectrum bandwidth at 6dB spectrum flatness.

[0119] Depend on Figures 14 to 16As can be seen from the experimental results shown, the pulse shaping device 2000 provided by the embodiments of the present application can perform pulse shaping on electro-optic comb pulses with picosecond-level pulse widths and narrowband spectral ranges, that is, compress the pulse width, suppress pulse side lobes, broaden the spectrum, and improve spectral flatness.

[0120] Those skilled in the art can clearly understand that for the convenience and simplicity of description, the specific working processes of the systems, devices, and units described above can refer to the corresponding processes in the foregoing method embodiments and will not be elaborated here.

[0121] In several embodiments provided by the present application, it should be understood that the disclosed systems, devices, and methods can be implemented in other ways. For example, the device embodiments described above are merely illustrative. For example, the division of the units is only a logical function division, and there may be other division methods in actual implementation. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the displayed or discussed couplings or direct couplings or communication connections to each other can be through some interfaces, and the indirect couplings or communication connections of the devices or units can be in electrical, mechanical, or other forms.

[0122] The units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they can be located in one place or distributed to multiple network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0123] In addition, the functional units in various embodiments of the present application can be integrated in a processing unit, or each unit can exist physically alone, or two or more units can be integrated in one unit. The above integrated units can be implemented in the form of hardware or in the form of software functional units.

[0124] When the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or all or part of this technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods described in various embodiments of this application. The aforementioned storage medium includes: various media that can store program codes, such as USB flash drives, mobile hard disks, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical discs.

Claims

1. A pulse shaping device, characterized in that, comprising: a first polarization controller, a first ring mirror assembly, a second polarization controller, and a polarization analyzer; The first polarization controller is configured to adjust the polarization state of a pulse signal to obtain a first polarized light, and input the first polarized light into a first port of the first ring mirror assembly, where the first polarized light includes linearly polarized light, elliptically polarized light, or circularly polarized light; The first ring mirror assembly includes an optical coupler and a nonlinear medium, a first port and a second port of the optical coupler are respectively connected to the first polarization controller and the second polarization controller, and a third port and a fourth port are respectively connected to two ends of the nonlinear medium; The second polarization controller is configured to connect the second port to the polarization analyzer and adjust the polarization state of a signal from the second port; The polarization analyzer is configured to perform polarization analysis on a signal from the second polarization controller and output a target pulse signal in a target polarization direction.

2. The device according to claim 1, characterized in that, the first ring mirror assembly is a nonlinear optical loop mirror (NOLM), and the coupling efficiencies at two ends of the nonlinear medium are different.

3. The device according to claim 1, characterized in that, the first ring mirror assembly is a nonlinear amplifying loop mirror (NALM), and the NALM includes the optical coupler, the nonlinear medium, and an optical amplifier; The optical coupler and the nonlinear medium form a loop, and the amplifier is in the loop.

4. The device according to claim 3, characterized in that, the optical amplifier is between the third port and the nonlinear medium, or between the fourth port and the nonlinear medium.

5. The device according to any one of claims 1 to 4, characterized in that, the third port and the fourth port are optical fibers.

6. The device according to any one of claims 1 to 5, characterized in that, the nonlinear medium includes a first medium, the materials of the third port and the fourth port are a second medium, and the nonlinear coefficient of the first medium is higher than that of the second medium.

7. The device according to any one of claims 1 to 6, characterized in that, the nonlinear medium includes an optical chip and / or a nonlinear optical fiber, and the optical chip includes at least one of the following materials: silicon dioxide, silicon nitride, tantalum oxide, or lithium niobate.

8. The device according to any one of claims 1 to 7, characterized in that, further comprising a second ring mirror assembly, and the second ring mirror assembly is located between the first ring mirror assembly and the second polarization controller.

9. The device according to claim 8, characterized in that, further comprising a third polarization controller; The third polarization controller is located between the first ring mirror assembly and the second ring mirror assembly and is configured to adjust the polarization state of a signal from the first ring mirror assembly.

10. The device according to any one of claims 1 to 9, characterized in that, the polarization analyzer is a polarization beam splitter; The polarization beam splitter includes two output ports, which are respectively used to output a first target pulse signal in a first polarization direction and a second target pulse signal in a second polarization direction, and the first polarization direction is perpendicular to the second polarization direction.

11. The device according to any one of claims 1 to 9, wherein, the polarization analyzing device is a polarizer.

12. The device according to any one of claims 1 to 11, wherein, it further includes an optical amplifier; the optical amplifier is used to amplify the input pulse signal of the pulse shaping device and input the amplified signal into the first polarization controller.

13. The device according to claim 12, wherein, it further includes an optical filter; the optical filter is located between the optical amplifier and the first polarization controller and is used to filter out optical noise to obtain the pulse signal.

14. A pulsed laser, wherein, it includes a seed pulse light source and the pulse shaping device according to any one of claims 1 to 13; the seed pulse light source is used to emit a pulse signal, and the pulse shaping device is used to shape the pulse signal.

15. The laser according to claim 14, wherein, the seed pulse light source includes any one of the following: an electro-optic frequency comb light source, a solid-state laser light source, a fiber laser light source or a semiconductor laser light source.

16. A detection system, wherein, it includes the pulsed laser according to claim 14 or 15 and a detector; the pulsed laser is used to emit pulsed laser light; the detector is used to detect the pulsed laser light that has passed through the substance to be measured.

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