Frequency-modulated light source, emission assembly and lidar

Abstract

The present disclosure provides a frequency-modulated light source, an emission assembly and a laser radar, the frequency-modulated light source comprising: a laser and a linewidth compression circuit; the laser is configured to generate initial light; the linewidth compression circuit is configured to receive a first optical signal, the first optical signal comprising at least part of the initial light or initial frequency-modulated light formed by modulating the initial light; the linewidth compression circuit is further configured to transmit the first optical signal and convert frequency information of the first optical signal into optical intensity information of a second optical signal; the linewidth compression circuit is further configured to generate a phase modulation signal according to the second optical signal; and the linewidth compression circuit is further configured to output the transmitted optical signal after modulation according to the phase modulation signal. The linewidth compression circuit outputs the transmitted optical signal after modulation according to the phase modulation signal, the feedback loop bandwidth is larger, and the performance of the frequency-modulated light source is greatly improved.

Description

Technical Field

[0001] This disclosure relates to laser detection, and more particularly to a frequency-modulated light source, a transmitting assembly, and a lidar. Background Technology

[0002] For lasers, the linewidth of the emitted light is a key performance indicator. When used for measurement, a smaller linewidth (full width at half maximum) allows for better distance measurement and accuracy. Frequency-modulated light sources have important applications in numerous scenarios such as lidar, optical frequency domain reflectometers, laser imaging, and biosensing.

[0003] Especially in frequency modulated continuous wave (FMCW) lidar, the smaller the linewidth of the frequency modulated light source and the better the frequency modulation linearity, the better the distance measurement capability and ranging accuracy that the lidar can achieve.

[0004] However, the output linewidth and output linearity of existing frequency-modulated light sources are not ideal. Summary of the Invention

[0005] The problem addressed by this disclosure is how to improve the output linewidth and output linearity of an FM light source.

[0006] To address the aforementioned problems, this disclosure provides a frequency-modulated light source, comprising:

[0007] The laser is configured to generate initial light; the linewidth compression circuit is configured to receive a first optical signal, the first optical signal including at least a portion of the initial light or initial frequency-modulated light formed by modulating the initial light; the linewidth compression circuit is further configured to transmit the first optical signal and convert the frequency information of the first optical signal into the intensity information of a second optical signal; the linewidth compression circuit is further configured to generate a phase modulation signal according to the second optical signal; the linewidth compression circuit is further configured to modulate the transmitted optical signal according to the phase modulation signal and then output it.

[0008] Optionally, the linewidth compression circuit includes: a conversion circuit, a signal generation circuit, and a first modulator; the conversion circuit is configured to transmit the first optical signal, convert the frequency information of the first optical signal into the light intensity information of the second optical signal, and convert the second optical signal into an electrical signal; the input terminal of the signal generation circuit is connected to the output terminal of the conversion circuit, and is configured to receive the electrical signal and output the phase modulation signal; the first modulator is configured to modulate the transmitted optical signal according to the phase modulation signal and then output it.

[0009] Optionally, the conversion circuit includes: a frequency discriminator and a photoelectric conversion circuit; the frequency discriminator is configured to transmit the first optical signal and output the second optical signal; the photoelectric conversion circuit is configured to receive the second optical signal and output an electrical signal reflecting the light intensity information.

[0010] Optionally, the frequency discriminator includes at least one of the following: a Mach-Zehnder interferometer, a fiber Bragg grating, a bandpass filter, and a microring.

[0011] Optionally, the conversion circuit further includes a second modulator configured to modulate the frequency of the operating point of the frequency discriminator according to a reference signal so that the frequency of the operating point of the frequency discriminator is equal to the center frequency of the initial light.

[0012] Optionally, the photoelectric conversion circuit is configured to separate at least a first sub-signal and a second sub-signal from the second optical signal, and is further configured to convert the first sub-signal into a first electrical signal and the second sub-signal into a second electrical signal respectively; the signal generation circuit generates a phase modulation signal based on the first electrical signal and the second electrical signal.

[0013] Optionally, the photoelectric conversion circuit is further configured to extract a third sub-signal from the second optical signal and convert the third sub-signal into a third electrical signal; the frequency-modulated light source further includes a center frequency feedback circuit, configured to generate a center frequency feedback signal based on the third electrical signal and provide it to the laser or the second modulator in the conversion circuit.

[0014] Optionally, the first modulator is configured to receive the initial light or the initial frequency-modulated light, and modulate the initial light or the initial frequency-modulated light based on the phase modulation signal before outputting it; the linewidth compression circuit further includes a first beam splitter, the input end of the first beam splitter is connected to the first modulator, the first output end of the first beam splitter outputs the first optical signal, and the second output end of the first beam splitter outputs outgoing light.

[0015] Optionally, the frequency-modulated light source further includes a second beam splitter, the input end of which receives the initial light or the initial frequency-modulated light, the first output end of which outputs the first optical signal, and the second output end of which outputs a third optical signal; the input end of the first modulator is connected to the second output end of the second beam splitter, and the first modulator is configured to modulate the third optical signal based on the phase modulation signal and output outgoing light.

[0016] Optionally, the frequency-modulated light source further includes: a delay unit, the input of which is connected to the second output of the second beam splitter, and the output of which is connected to the input of the first modulator.

[0017] Optionally, the first modulator includes at least one of a phase modulator, an IQ modulator, a semiconductor optical amplifier, and an acousto-optic modulator.

[0018] Optionally, when the initial light is frequency-modulated light, or when the linewidth compression circuit receives the initial frequency-modulated light, the signal generation circuit includes an integrator circuit configured to receive the electrical signal and output the phase-modulated signal.

[0019] Optionally, the initial light is fixed-frequency light, and the first modulator includes an IQ modulator; the signal generation circuit includes an electrical signal coupler, which is configured to output the phase modulation signal; the IQ modulator modulates the transmitted optical signal according to the phase modulation signal and outputs frequency-modulated light.

[0020] Optionally, the electrical signal coupler includes a voltage-controlled oscillator.

[0021] Optionally, the frequency-modulated light source includes: multiple lasers, which generate multiple initial lights in a time-division manner; the difference in the center wavelength of the initial lights generated by different lasers is an integer multiple of the frequency discrimination period, wherein the frequency discrimination period is the period during which the amplitude of the second optical signal changes with the frequency of the first optical signal.

[0022] Optionally, the laser generates multiple initial lights of different wavelengths in a time-division manner, and the difference in the center wavelength of the initial lights of different wavelengths is an integer multiple of the frequency discrimination period, wherein the frequency discrimination period is the period during which the amplitude of the second optical signal changes with the frequency of the first optical signal.

[0023] Accordingly, this disclosure also provides a transmitting component, including: a frequency-modulated light source, the frequency-modulated light source including: a laser and a linewidth compression circuit; the laser is configured to generate initial light; the linewidth compression circuit is configured to receive a first optical signal, the first optical signal including at least a portion of the initial light or initial frequency-modulated light formed by modulating the initial light; the linewidth compression circuit is further configured to transmit the first optical signal and convert the frequency information of the first optical signal into the light intensity information of a second optical signal; the linewidth compression circuit is further configured to obtain the frequency noise of the initial light according to the second optical signal to generate a phase modulation signal; the linewidth compression circuit is further configured to modulate the transmitted optical signal according to the phase modulation signal and output it to form emitted light.

[0024] Optionally, it may also include: at least one lens located in the optical path downstream of the emitted light, the at least one lens being configured to shape the emitted light.

[0025] Furthermore, this disclosure also provides a lidar, comprising: a transmitting component, the transmitting component including: a frequency-modulated light source, the frequency-modulated light source including: a laser and a linewidth compression circuit; the laser configured to generate initial light; the linewidth compression circuit configured to receive a first optical signal, the first optical signal including at least a portion of the initial light or initial frequency-modulated light formed by modulation of the initial light; the linewidth compression circuit further configured to transmit the first optical signal and convert the frequency information of the first optical signal into the light intensity information of a second optical signal; the linewidth compression circuit further configured to obtain the frequency noise of the initial light according to the second optical signal to generate a phase modulation signal; the linewidth compression circuit further configured to modulate the transmitted optical signal according to the phase modulation signal and output it to form emitted light; the emitted light is reflected by an object to form echo light; and a receiving component configured to receive the echo light.

[0026] Compared with the prior art, the technical solution disclosed herein has the following advantages:

[0027] In this disclosed technical solution, the linewidth compression circuit of the frequency-modulated light source converts the frequency information of the first optical signal into the light intensity information of the second optical signal, and thereby generates a phase modulation signal. The linewidth compression circuit is further configured to modulate the transmitted optical signal according to the phase modulation signal and then output it. The linewidth compression circuit modulates the transmitted optical signal according to the phase modulation signal and then outputs it, resulting in a larger feedback loop bandwidth and greatly improving the performance of the frequency-modulated light source. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of this disclosure or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are merely embodiments of this disclosure. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort. The drawings are used to provide a further understanding of this disclosure and constitute a part of the specification. They are used together with the embodiments of this disclosure to explain this disclosure and do not constitute a limitation of this disclosure. In the drawings:

[0029] Figure 1 A functional block diagram of a first embodiment of the frequency-modulated light source of this disclosure is shown.

[0030] Figure 2 It shows Figure 1 The diagram shows a structural schematic of an embodiment of a frequency-modulated light source.

[0031] Figure 3 It shows Figure 1 The diagram shows the frequency change over time of the first optical signal input to the frequency discriminator in the frequency-modulated light source embodiment shown.

[0032] Figure 4 It shows Figure 1 The diagram shows the change in light intensity over time of the second optical signal output by the frequency discriminator in the frequency-modulated light source embodiment.

[0033] Figure 5 A schematic diagram of the structure of the second embodiment of the frequency-modulated light source disclosed herein is shown.

[0034] Figure 6 A schematic diagram of the structure of the third embodiment of the frequency modulation light source disclosed herein is shown.

[0035] Figure 7 A schematic diagram of the structure of the fourth embodiment of the frequency-modulated light source disclosed herein is shown.

[0036] Figure 8 A schematic diagram of the structure of the fifth embodiment of the frequency modulation light source disclosed herein is shown.

[0037] Figure 9 A schematic diagram of the structure of the sixth embodiment of the frequency modulation light source of this disclosure is shown.

[0038] Figure 10 A schematic diagram of the structure of the seventh embodiment of the frequency modulation light source disclosed herein is shown.

[0039] Figure 11 A schematic diagram of the structure of the eighth embodiment of the frequency modulation light source of this disclosure is shown. Detailed Implementation

[0040] In the following description, only certain exemplary embodiments are briefly described. As those skilled in the art will recognize, the described embodiments can be modified in various ways without departing from the spirit or scope of this disclosure. Therefore, the drawings and description are to be considered exemplary in nature and not restrictive.

[0041] In the description of this disclosure, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing this disclosure and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this disclosure. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of the stated features. In the description of this disclosure, "a plurality of" means two or more, unless otherwise explicitly specified.

[0042] In the description of this disclosure, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linkage" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections, electrical connections, or connections that allow for communication; they can refer to direct connections or indirect connections through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this disclosure according to the specific circumstances.

[0043] In this disclosure, unless otherwise expressly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0044] The following disclosure provides numerous different embodiments or examples for implementing various structures of this disclosure. To simplify the disclosure, specific examples of components and arrangements are described below. These are merely examples and are not intended to limit the scope of this disclosure. Furthermore, reference numerals and / or letters may be repeated in different examples; such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed. In addition, various specific examples of processes and materials are provided in this disclosure, but those skilled in the art will recognize the application of other processes and / or the use of other materials.

[0045] As can be seen from the background technology, existing frequency-modulated light sources have problems with less than ideal output linewidth and output linearity.

[0046] There are two main methods for frequency sweeping of existing frequency-modulated light sources: one is external modulation, in which the laser emits fixed-frequency light, and a radio frequency signal is loaded onto the fixed-frequency light through an electro-optic modulator to achieve frequency modulation. This external modulation method has very low integration, requires a narrow-linewidth laser such as an external cavity laser (linewidth is about 10 kHz), which is very expensive, and the mode-hopping nature of the external cavity laser will cause the frequency-modulated light source to be unstable.

[0047] Another method is direct modulation, which involves changing the laser's operating current to achieve linear frequency modulation of its operating wavelength. Direct modulation can be achieved by directly modulating the current of a distributed feedback laser (DFB). However, DFBs have a very wide linewidth (approximately 100 kHz), requiring the use of an opto-locked loop or frequency discriminator to compress the linewidth and optimize the frequency modulation linearity. But because the laser's response is slow and the feedback loop bandwidth is narrow (typically less than 1 MHz), this results in significant residual frequency noise, thus affecting measurement accuracy.

[0048] To address the aforementioned technical problem, this disclosure provides a frequency-modulated light source, which may include: a laser and a linewidth compression circuit; the laser can generate initial light; the linewidth compression circuit can receive a first optical signal, the first optical signal may include at least a portion of the initial light or initial frequency-modulated light formed by modulating the initial light; the linewidth compression circuit can also transmit the first optical signal and convert the frequency information of the first optical signal into the intensity information of a second optical signal; the linewidth compression circuit can also generate a phase modulation signal based on the second optical signal; the linewidth compression circuit can also modulate the transmitted optical signal based on the phase modulation signal and output it.

[0049] The technical solution disclosed herein includes a linewidth compression circuit for the frequency-modulated light source that can convert the frequency information of a first optical signal into the intensity information of a second optical signal, thereby generating a phase modulation signal. The linewidth compression circuit can also modulate the transmitted optical signal according to the phase modulation signal before outputting it. Because the linewidth compression circuit can modulate the transmitted optical signal according to the phase modulation signal before outputting it, the feedback loop bandwidth is larger, which can greatly improve the performance of the frequency-modulated light source.

[0050] To make the above-mentioned objects, features and advantages of this disclosure more apparent and understandable, specific embodiments of this disclosure will be described in detail below with reference to the accompanying drawings.

[0051] refer to Figure 1 and Figure 2 ,in Figure 1 A functional block diagram of the first embodiment of the frequency modulation light source of this disclosure is shown; Figure 2 It shows Figure 1 The diagram shown is a structural schematic of an embodiment of the frequency modulation light source disclosed herein.

[0052] The frequency-modulated light source includes a laser 110 and a linewidth compression circuit 120. The laser 110 can generate initial light. The linewidth compression circuit 120 can receive a first optical signal, which may include at least a portion of the initial light or initial frequency-modulated light formed by modulating the initial light. The linewidth compression circuit 120 can also transmit the first optical signal and convert the frequency information of the first optical signal into the intensity information of a second optical signal. The linewidth compression circuit 120 can also generate a phase modulation signal based on the second optical signal. The linewidth compression circuit 120 can also modulate the transmitted optical signal based on the phase modulation signal and output it.

[0053] The specific technical solutions of the frequency modulation light source embodiments of this disclosure are described in detail below with reference to the accompanying drawings.

[0054] The laser is used to generate light.

[0055] In some embodiments of this disclosure, the laser may be a distributed feedback laser (DFB).

[0056] In some embodiments, the laser can be a fixed-frequency laser, and the initial light generated by the laser can be fixed-frequency light. In other embodiments of this disclosure, the laser can be modulated by current, and the initial light generated by the laser can also be frequency-modulated light. In other embodiments of this disclosure, the initial light generated by the laser can be fixed-frequency light, and the frequency-modulated light source can further include an electro-optic modulator to modulate the fixed-frequency light to obtain frequency-modulated light.

[0057] It should be noted that the frequency-modulated light source may further include a frequency modulation circuit, which can generate a reference signal for frequency modulation.

[0058] In some embodiments, the frequency modulation circuit can be connected to the laser. The frequency modulation circuit can provide a reference signal to the laser. The output frequency of the laser can have a fixed relationship with the current: the larger the current, the lower the output frequency; a driving current whose magnitude varies with the amplitude of the reference signal can be generated according to the reference signal, thereby changing the output frequency of the laser to achieve frequency modulation. In specific implementations, the amplitude of the reference signal and the corresponding output frequency of the laser change linearly with time, and the change pattern can be in the form of sawtooth wave, triangular wave, trapezoidal wave, etc.

[0059] In other embodiments, the frequency modulation circuit can be connected to an electro-optic modulator so that the modulation signal of the electro-optic modulator corresponds to the reference signal. The electro-optic modulator modulates the frequency of the fixed-frequency light output by the laser, thereby controlling the frequency change of the frequency-modulated light over time to correspond to the amplitude change of the reference signal.

[0060] For example, such as Figure 1 and Figure 2 As shown, the frequency modulation circuit 130 is connected to the laser 110. The frequency modulation circuit 130 provides a reference signal to the laser 110 and changes the current of the laser 110 to change the frequency of the light generated by the laser 110, thereby achieving frequency modulation.

[0061] The linewidth compression circuit is used to modulate the transmitted optical signal to compress the linewidth.

[0062] In some embodiments of this disclosure, the linewidth compression circuit may include: a conversion circuit, a signal generation circuit, and a first modulator; the conversion circuit can transmit the first optical signal, convert the frequency information of the first optical signal into the light intensity information of the second optical signal, and convert the second optical signal into an electrical signal; the input terminal of the signal generation circuit can be connected to the output terminal of the conversion circuit, receive the electrical signal, and output the phase modulation signal; the first modulator can modulate the transmitted optical signal according to the phase modulation signal and output it.

[0063] The conversion circuit can convert the frequency information of the first optical signal into the light intensity information of the second optical signal, and can convert the second optical signal into an electrical signal.

[0064] In some embodiments, the conversion circuit may include a frequency discriminator and a photoelectric conversion circuit; the frequency discriminator may transmit the first optical signal and output the second optical signal; the photoelectric conversion circuit may receive the second optical signal and output an electrical signal reflecting the light intensity information.

[0065] The frequency discriminator can transmit the first optical signal and generate a second optical signal based on the frequency information of the first optical signal, thereby converting the frequency information of the first optical signal into the light intensity information of the second optical signal.

[0066] The frequency discriminator can be an optical frequency discriminator, which is an optical component that outputs an optical signal with a frequency corresponding to the frequency of the input optical signal. The relationship curve between the intensity of the output optical signal and the frequency of the input optical signal is the frequency intensity curve of the frequency discriminator. The frequency discriminator is highly sensitive to changes in the frequency of the transmitted optical signal. Even a small change in the frequency of the first optical signal can cause a significant change in the intensity of the second optical signal output by the frequency discriminator.

[0067] When the frequency of the initial light generated by the laser fluctuates, the linewidth of the laser increases. This frequency fluctuation includes at least a portion of the initial light or the frequency of a first optical signal formed by modulating the initial light into an initial frequency-modulated light, which also fluctuates accordingly. The frequency discriminator can convert the frequency fluctuation of the first optical signal into a change in the intensity of a second optical signal.

[0068] The frequency discriminator has an operating point. The operating point of the frequency discriminator is located at the half-width at half-maximum (WHM) of its frequency intensity curve. When the frequency of the input optical signal is at the operating point, the jitter of the input optical signal frequency is in a linear segment. The jitter of the first optical signal frequency linearly causes the jitter of the second optical signal intensity, such as... Figure 3 and Figure 4 As shown.

[0069] In some embodiments, the frequency discriminator may include at least one of the following: a Mach-Zehnder interferometer, a fiber Bragg grating, a bandpass filter, and a microring. For example, Figure 2 As shown, the frequency discriminator 1211 is a Mach-Zehnder interferometer. The frequency discriminator 1211 includes a beam splitter SPA, the input of which is adapted to receive a first optical signal. The beam splitter SPA splits the first beam splitter into two analysis signals, which are output from the two outputs of the beam splitter SPA to the two arms (optical paths) of the Mach-Zehnder interferometer, respectively. In the Mach-Zehnder interferometer, the two optical paths with a preset optical path difference transmit the two analysis signals separately and then combine them to form the second optical signal. Since there is an optical path difference between the optical paths through which the different analysis signals are transmitted, there is a phase difference between the two analysis signals when they are combined. The light intensity of the second optical signal formed by the combined beam is related to the phase difference between the analysis signals.

[0070] The frequency intensity curve of a Mach-Zehnder interferometer exhibits a sinusoidal or cosine-square variation. The width of the transmission peak in the frequency intensity curve is affected by the arm length difference, temperature, and refractive index, and can be expressed as: Where FSR represents the full width at half maximum (FWHM) of the transmission peak, c represents the speed of light, n represents the refractive index, and L represents the arm length difference. For example, when the arm length difference is 0.5 m, the FWHM of the transmission peak at a wavelength of 1555 nm is approximately 200 MHz.

[0071] In some embodiments, the conversion circuit may further include a second modulator, which can modulate the frequency of the operating point of the frequency discriminator according to a reference signal so that the frequency of the operating point of the frequency discriminator is equal to the center frequency of the initial light.

[0072] The second modulator can modulate the frequency of the operating point of the frequency discriminator to form a frequency discriminator with an adjustable operating point, so that the operating point frequency of the frequency discriminator is equal to the operating frequency of the initial light, thereby suppressing external low-frequency disturbances, making the frequency discriminator work in the linear segment, and making the jitter of the intensity of the second optical signal linearly reflect the jitter of the frequency of the first optical signal.

[0073] In some embodiments, the second modulator may include at least one of a phase modulator, an IQ modulator, a semiconductor optical amplifier (SOA), and an acousto-optic modulator.

[0074] For example, such as Figure 2 As shown, the frequency discriminator 1211 is a Mach-Zehnder interferometer. The second modulator 1213 includes a phase modulator located in one optical path of the Mach-Zehnder interferometer. For example, the phase modulator modulates the phase of the optical signal by applying a phase that varies linearly with voltage to the optical field of the transmitted optical signal through electrodes.

[0075] It should be noted that in other embodiments, the frequency discriminator may also be a fiber Bragg grating, a bandpass filter, or a microring. As the frequency discriminator changes, the second modulator also changes. For example, if the frequency discriminator is a fiber Bragg grating with a thermally modulated phase shift region, the second modulator may include a temperature-adjusting element that can change the temperature of the thermally modulated phase shift region to change the refractive index. Alternatively, the frequency discriminator may be a microring, and the second modulator may include a modulation circuit that generates a refractive index modulation signal that can change the refractive index of the microring.

[0076] It should also be noted that the reference signal is generated by a frequency modulation circuit. For example, such as... Figure 1 and Figure 2 As shown, the frequency modulation circuit 130 is connected to the second modulator 1213 of the linewidth compression circuit 120, and the frequency modulation circuit 130 provides the reference signal to the linewidth compression circuit 120.

[0077] The conversion circuit 121 may further include a photoelectric conversion circuit. The photoelectric conversion circuit may include a detector to receive the second optical signal and perform photoelectric conversion on the second optical signal to generate an electrical signal that reflects the light intensity information of the second optical signal.

[0078] The light intensity information of the second optical signal is obtained by converting the frequency information of the first optical signal. The light intensity information of the second optical signal can reflect the frequency information of the first optical signal, and the electrical signal generated by the photoelectric conversion circuit can also reflect the frequency information of the first optical signal.

[0079] In some embodiments, the photoelectric conversion circuit can separate at least a first sub-signal and a second sub-signal from the second optical signal, and can also convert the first sub-signal into a first electrical signal and the second sub-signal into a second electrical signal, respectively.

[0080] The first sub-signal and the second sub-signal can be balanced to obtain the phase noise of the first optical signal, which can cancel the light intensity noise of the initial light generated by the laser and the noise caused by environmental jitter. This can eliminate the influence of the light intensity jitter of the initial light generated by the laser and environmental jitter on the light intensity information of the second optical signal, thereby achieving linewidth compression and suppressing nonlinear phase error in the frequency modulation process.

[0081] For example, such as Figure 2 As shown, the photoelectric conversion circuit 1212 includes a first detector PD1 and a second detector PD2. The first detector PD1 is used to receive the first sub-signal and convert the first sub-signal into a first electrical signal, and the second detector PD2 is used to receive the second sub-signal and convert the second sub-signal into a second electrical signal.

[0082] Furthermore, in some embodiments, the photoelectric conversion circuit can also extract a third sub-signal from the second optical signal and convert the third sub-signal into a third electrical signal. The frequency-modulated light source may also include a center frequency feedback circuit, which can generate a center frequency feedback signal based on the third electrical signal and provide it to the laser or the second modulator in the conversion circuit.

[0083] The third electrical signal can stabilize the operating point of the frequency discriminator, ensuring that the center frequency of the first optical signal always matches the operating frequency of the frequency discriminator, thereby suppressing low-frequency disturbances. The function of the center frequency feedback signal is to ensure that the center frequency of the first optical signal always matches the operating frequency of the frequency discriminator.

[0084] like Figure 2As shown, the photoelectric conversion circuit 1212 further includes a third detector PD3, which is used to receive the third sub-signal and convert the third sub-signal into a third electrical signal; the center frequency feedback circuit 140 is connected to the third detector PD3 to receive the third electrical signal obtained by converting the third sub-signal; the center frequency feedback circuit 140 is connected to the second modulator 1213 so that the frequency of the operating point of the frequency discriminator moves with the center frequency of the first optical signal.

[0085] It should be noted that when the center frequency feedback circuit provides the generated center frequency feedback signal to the second modulator in the conversion circuit, the frequency-modulated light source may also have an adder, which can couple the center frequency feedback signal and the reference signal to be applied to the second modulator.

[0086] For example, such as Figure 2 As shown, the two input terminals of the adder 1214 are connected to the frequency modulation circuit 130 and the center frequency feedback circuit 140, respectively, receiving a reference signal and a center frequency feedback signal from the frequency modulation circuit 130 and the center frequency feedback circuit 140 for coupling. The output terminal of the adder 1214 is connected to the second modulator, loading the coupling result onto the second modulator. The operating point frequency of the frequency discriminator configured with the second modulator is adjustable. As the signal loaded onto the second modulator changes, the operating point of the frequency discriminator shifts in the frequency domain, a V π A change in voltage can shift the free spectral range (FSR) by half.

[0087] In some embodiments, the photoelectric conversion circuit can separate a first sub-signal, a second sub-signal, and a third sub-signal from the second optical signal through multiple beam splitting. For example, such as... Figure 2As shown, the photoelectric conversion circuit 1212 further includes: a first-stage beam splitter SP1 and two second-stage beam splitters SP2. The input terminal of the first-stage beam splitter SP1 is connected to the output terminal of the frequency discriminator 1211 to receive the second optical signal output by the frequency discriminator 1211. The two output terminals of the first-stage beam splitter SP1 are respectively connected to the input terminals of the two second-stage beam splitters SP2. The first-stage beam splitter SP1 divides the second optical signal into two preliminary signals and outputs them to the two second-stage beam splitters SP2 respectively. The second-stage beam splitter SP2 divides the preliminary signal into two sub-signals to be output to different detectors. One output terminal of one second-stage beam splitter SP2 is connected to the first detector PD1 to realize the reception and conversion of the first sub-signal. One output terminal of the other second-stage beam splitter SP2 is connected to the second detector PD2 to realize the reception and conversion of the second sub-signal. The other output terminal of one of the two second-stage beam splitters SP2 is connected to the third detector PD3 to realize the reception and conversion of the third sub-signal.

[0088] It should be noted that, as Figure 2 As shown, in some embodiments, the photoelectric conversion circuit 1212 further includes a fourth detector PD4, which is connected to the other output terminal of the other of the two secondary beam splitters SP2 to receive the split fourth sub-signal and avoid interference caused by the fourth sub-signal. In other embodiments, the fourth sub-signal can also be used for balance point detection. The electrical signal generated by the fourth detector PD4 receiving the fourth sub-signal is suitable for balance point detection.

[0089] It should also be noted that in some embodiments, the photoelectric conversion circuit divides the second optical signal into a first sub-signal, a second sub-signal, and a third sub-signal by dividing it into multiple equal parts. The splitting ratio of the first-stage beam splitter SP1 and the second-stage beam splitter SP2 is 1:1. For example, the first-stage beam splitter SP1 and the second-stage beam splitter SP2 are both 1:1 optical couplers.

[0090] The signal generation circuit can be connected to the conversion circuit, and can receive the electrical signal generated by the conversion circuit converting the second optical signal and output the phase modulation signal according to the electrical signal.

[0091] In some embodiments, the photoelectric conversion circuit in the conversion circuit can separate a first sub-signal and a second sub-signal from the second optical signal and convert them into a first electrical signal and a second electrical signal respectively for balanced detection; the signal generation circuit can generate a phase modulation signal based on the first electrical signal and the second electrical signal.

[0092] For example, such as Figure 2As shown, the first detector PD1 and the second detector PD2 receive the first sub-signal and the second sub-signal respectively to generate a first electrical signal I1 and a second electrical signal I2; the first detector PD1 and the second detector PD2 are connected in parallel to perform balanced detection, and the electrical signal obtained by the signal generation circuit 122 from the photoelectric conversion circuit 1212 is the difference ΔI = I1 - I2 between the first electrical signal I1 and the second electrical signal I2.

[0093] In some embodiments, the initial light is frequency-modulated light, or when the linewidth compression circuit receives the initial frequency-modulated light, the signal generation circuit can receive the electrical signal and output the phase-modulated signal.

[0094] The electrical signal obtained by the balanced detection of the first detector PD1 and the second detector PD2 can be expressed as: , where θ(t) is the phase information output by the frequency discriminator after integration; the integrator circuit integrates the electrical signal and outputs the phase modulation signal Kθ(t).

[0095] For example, such as Figure 2 As shown, the signal generation circuit 122 is connected to both the first detector PD1 and the second detector PD2 to obtain the electrical signal obtained by balanced detection; the signal generation circuit 122 integrates the electrical signal to obtain the phase modulation signal; in addition, in some embodiments, the signal generation circuit 122 can also gain the integration result of the signal generation circuit 122 to obtain the phase modulation signal.

[0096] It should be noted that, in some other embodiments of the present invention, the signal generation circuit may include an integrating circuit, which can receive the electrical signal and output the phase modulation signal. The integrating circuit can also amplify the electrical signal, integrating and amplifying the received electrical signal before outputting it.

[0097] In other embodiments, the signal generation circuit may further include a gain circuit that can amplify the integration result of the integrator circuit to obtain the phase modulation signal.

[0098] For example, such as Figure 5As shown, the signal generation circuit 122 includes an integrator circuit 1221 and a gain circuit 1223. The integrator circuit 1221 receives the electrical signal obtained by the first detector PD1 and the second detector PD2 through balanced detection, and integrates the electrical signal. The gain circuit 1223 is connected to the integrator circuit 1221 and amplifies the integration result of the integrator circuit 1221 to obtain the phase modulation signal. The first modulator can modulate the transmitted optical signal according to the phase modulation signal and output it.

[0099] The phase modulation signal can reflect the frequency jitter of the first optical signal; the first modulator can modulate the transmitted optical signal according to the phase modulation signal. The modulation amplitude of the first modulator can correspond to the frequency jitter amplitude of the first optical signal, and the modulation direction is opposite to the direction of frequency jitter, thereby eliminating the frequency jitter of the transmitted optical signal. This can stabilize the frequency of the optical signal modulated by the first modulator at the center frequency, thereby reducing the frequency jitter of the emitted light and compressing the width of the emitted light beam.

[0100] In some embodiments, the first modulator can receive the initial light or the initial frequency-modulated light, and modulate the initial light or the initial frequency-modulated light based on the phase modulation signal before outputting it; the linewidth compression circuit may further include a first beam splitter, the input of which may be connected to the first modulator, the first output of which may output the first optical signal, and the second output of which may output outgoing light. For example, the outgoing light may be emitted into external space for obstacle detection.

[0101] The input of the first modulator can receive the initial light or the initial frequency-modulated light; the output of the first modulator can be connected to the input of the first beam splitter, which can split the light modulated by the first modulator into the outgoing light and the first optical signal. The outgoing light, modulated by the first modulator, has an optical field that can be expressed as:

[0102] In some embodiments, the first modulator may include at least one of a phase modulator, an IQ modulator, a semiconductor optical amplifier, and an acousto-optic modulator.

[0103] For example, such as Figure 2As shown, the first modulator 123 is a phase modulator. The input terminal of the first modulator 123 is connected to the laser 110 to receive the initial light; the output terminal of the first modulator 123 is connected to the input terminal of the first beam splitter 124 to provide modulated light to the first beam splitter 124; the first beam splitter 124 splits the light modulated by the first modulator 123 into a first optical signal and an outgoing light.

[0104] The emitted light is light modulated by the first modulator 123. The frequency jitter of the emitted light is eliminated during the modulation process of the first modulator 123, and the linewidth of the emitted light is compressed during the modulation process, resulting in a smaller linewidth of the emitted light.

[0105] In some embodiments, the first beam splitter has a large splitting ratio; the ratio of the energy of the emitted light split by the first beam splitter to the energy of the split first optical signal is N, where N is greater than 1, to maximize the emitted light energy. For example, such as... Figure 2 As shown, the splitting ratio of the first beam splitter 124 is greater than or equal to 9:1; the ratio of the energy of the outgoing light split by the first beam splitter 124 to the energy of the split first optical signal is greater than or equal to 9.

[0106] It should be noted that the first beam splitter can be located in the optical path downstream of the first modulator. The first beam splitter can receive light rays modulated by the first modulator. The first optical signal can be an initial frequency-modulated light formed by modulating a portion of the initial light.

[0107] refer to Figure 6 A schematic diagram of the structure of the fourth embodiment of the frequency modulation light source disclosed herein is shown. It should be noted that, Figure 6 The structures of the lasers and photoelectric conversion circuits in some of the embodiments shown can be the same as those in the aforementioned embodiments.

[0108] In some embodiments of this disclosure, the frequency discriminator does not include a second modulator, and the operating frequency of the frequency discriminator is a fixed value and cannot be adjusted.

[0109] In some embodiments, the signal generation circuit can output a phase-modulated signal based on the electrical signal converted by the conversion circuit and the reference signal generated by the frequency modulation circuit.

[0110] The signal generation circuit can subtract the reference signal during the integration and gain process of the electrical signal obtained by the conversion circuit, which can also eliminate the effect of frequency modulation on linewidth compression.

[0111] For example, such as Figure 6As shown, the frequency modulation circuit 230 is connected to the signal generation circuit 222 of the linewidth compression circuit 220, providing a reference signal to the signal generation circuit 222. After integrating and gaining the electrical signals obtained from the balanced detection and conversion of the first detector PD1 and the second detector PD2 in the photoelectric conversion circuit 221 of the conversion circuit 221, the signal generation circuit 222 subtracts the reference signal from the gain result to generate the phase modulation signal, which is then provided to the first modulator 223.

[0112] Furthermore, since the frequency discriminator does not contain a second modulator, its operating frequency is fixed. The center frequency feedback signal generated by the center frequency feedback circuit can be provided to the laser to match the center frequency of the first optical signal with the operating frequency of the frequency discriminator, thus achieving the same purpose of suppressing low-frequency disturbances.

[0113] For example, such as Figure 6 As shown, the center frequency feedback circuit 240 is connected between the laser 210 and the third detector PD3 of the photoelectric conversion circuit 2212 in the conversion circuit 221 within the linewidth compression circuit 220, providing the center frequency feedback signal to the laser 210. The laser 210 adjusts the center frequency of the generated light according to the center frequency feedback signal.

[0114] refer to Figure 7 The diagram shows a structural schematic of the fourth embodiment of the frequency modulation light source disclosed herein.

[0115] It should be noted that, Figure 7 The structures of the lasers and photoelectric conversion circuits in some of the embodiments shown can be the same as those in the aforementioned embodiments.

[0116] In some embodiments of this disclosure, the frequency-modulated light source may further include a second beam splitter. The input end of the second beam splitter may receive the initial light or the initial frequency-modulated light. The first output end of the second beam splitter may output the first optical signal, and the second output end of the second beam splitter may output a third optical signal. The input end of the first modulator may be connected to the second output end of the second beam splitter. The first modulator may modulate the third optical signal based on the phase modulation signal and then output the emitted light.

[0117] After the second beam splitter can split the initial light or initial frequency-modulated light into a first optical signal and a third optical signal, the linewidth compression circuit can convert the frequency information of the first optical signal into the light intensity information of the second optical signal to generate the phase modulation signal, and can modulate the third optical signal according to the phase modulation signal to form the outgoing light.

[0118] For example, such as Figure 7 As shown, the input terminal of the second beam splitter 325 is connected to the light source 310 to receive the initial light; the second beam splitter 325 splits the initial light into a first optical signal and a third optical signal, which are respectively provided to the first output terminal and the second output terminal. The first optical signal and the third optical signal are portions of the initial light.

[0119] In some embodiments, the second beam splitter has a large splitting ratio; the ratio of the energy of the emitted light split by the second beam splitter to the energy of the split first optical signal is N, where N is greater than 1, to maximize the emitted light energy. For example, such as... Figure 7 As shown, the splitting ratio of the second beam splitter 325 is greater than or equal to 9:1; the ratio of the energy of the third optical signal to the energy of the first optical signal is greater than or equal to 9.

[0120] Continue to refer to Figure 7 The first output terminal of the second beam splitter 325 is connected to the frequency discriminator 3211 of the conversion circuit 321 in the linewidth compression circuit 320. The frequency discriminator 3211 receives the first optical signal provided to the first output terminal and converts the frequency information of the first optical signal into the light intensity information of the second optical signal. The photoelectric conversion circuit 3212 of the conversion circuit 321 receives the second optical signal. The first detector PD1 and the second detector PD2 output electrical signals reflecting the light intensity information of the second optical signal through balanced detection. The integrator circuit 3221 and the gain circuit 3223 of the signal generation circuit 322 integrate and gain the electrical signal output by the photoelectric conversion circuit 3212 to form the phase modulation signal.

[0121] In some embodiments of this disclosure, the frequency-modulated light source may further include: a delay unit, the input terminal of which may be connected to the second output terminal of the second beam splitter, and the output terminal of which may be connected to the input terminal of the first modulator.

[0122] The delay unit can be used to match the delay of the feedforward signal. The linewidth compression circuit can convert the frequency information of the first optical signal into the light intensity information of the second optical signal to generate the phase modulation signal, which requires a certain amount of time. The delay unit can extend the optical path of the third optical signal to match the time difference between generating the phase modulation signal and the third optical signal, so that the third optical signal can be modulated before emission.

[0123] For example, such as Figure 7 As shown, the delay unit 350 is connected in the optical path between the second beam splitter 325 and the first modulator 323. In a specific implementation, the delay unit 350 can be a delay fiber.

[0124] In some embodiments, the frequency-modulated light source may further include a center frequency feedback circuit 340. The center frequency feedback circuit 340 may be the same as or similar to the center frequency feedback circuit 240 in the foregoing embodiments.

[0125] In other embodiments, the center frequency feedback circuit 340 may be the same as or similar to the center frequency feedback circuit 340 in the foregoing embodiments.

[0126] refer to Figure 8 The diagram shows a structural schematic of the fifth embodiment of the frequency modulation light source disclosed herein.

[0127] It should be noted that, Figure 8 The structures of the lasers and photoelectric conversion circuits in some of the embodiments shown can be the same as those in the aforementioned embodiments.

[0128] In some embodiments of this disclosure, the initial light is fixed-frequency light, and the first modulator may include an IQ modulator; the signal generation circuit may include an electrical signal coupler, which can output the phase modulation signal; the IQ modulator can modulate the transmitted optical signal according to the phase modulation signal and output frequency-modulated light.

[0129] An IQ modulator is a device with phase modulation characteristics. An IQ modulator consists of two sub-Mach-Zehnder interferometers and one master Mach-Zehnder interferometer, and phase modulation can be achieved by adjusting three voltages.

[0130] Furthermore, the center frequency before entering the IQ modulator is at k=0, and it changes to k=-1 after outputting from the IQ modulator. The IQ modulator, in conjunction with an electrical signal coupler, couples the electrical signal generated by the balanced detection result with the reference signal. In specific implementations, the electrical signal coupler can have an ideal integration effect on the phase, and the signal generation circuit with the electrical signal coupler performs integration through the electrical signal coupler.

[0131] For example, such as Figure 8 As shown, the signal generation circuit 422 is connected to the first detector PD1 and the second detector PD2 to receive the electrical signal generated by the balanced detection result. The signal generation circuit 422 is also connected to the frequency modulation circuit 430 to receive the reference signal. The electrical signal coupler 4222 of the signal generation circuit 422 couples the electrical signal generated by the balanced detection result and the reference signal. The signal generation circuit 422 is also connected to the first modulator 423 to provide the coupling result to the first modulator 423.

[0132] In some specific implementations, the electrical signal coupler 4222 includes a voltage-controlled oscillator (VCO). The signal generation circuit 422 amplifies the electrical signal, and the amplified electrical signal is integrated by the electrical signal coupler 4222 and coupled with a reference signal before being provided to the first modulator 423.

[0133] In addition, the frequency modulation circuit 430 is also connected to the second modulator 4213, providing a reference signal to the second modulator 4213 so that the frequency of the operating point of the frequency discriminator 4211 matches the center frequency of the first optical signal.

[0134] The initial light is fixed-frequency light. The optical signal transmitted by the first modulator 423 is fixed-frequency light. The reference signal generated by the frequency modulation circuit 430 is coupled with the electrical signal generated by the balanced detection result through the electrical signal coupler 4222. Therefore, the fixed-frequency light is frequency-modulated, and linewidth compression is achieved to output narrow-linewidth frequency-modulated light.

[0135] In some embodiments, the electrical signal generated by the balanced detection result coupled to the reference signal is a gained electrical signal. The electrical signal generated by the balanced detection result is amplified before being coupled to the reference signal.

[0136] It should be noted that the input of the IQ modulator receives a pair of orthogonal signals; the frequency-modulated light source further includes a signal decomposer, which decomposes the coupling result provided by the electrical signal coupler into a pair of orthogonal signals and provides them to the IQ modulator. For example, as... Figure 8 As shown, the signal decomposer 423a is a 90° bridge connected between the signal generation circuit 422 and the first modulator 423.

[0137] It should also be noted that the input terminal of the first modulator 423 is connected to the light source 410 to receive the initial light; the frequency-modulated light source may also include a center frequency feedback circuit 440. The center frequency feedback circuit 440 may be the same as or similar to the center frequency feedback circuit 240 or 340 in the foregoing embodiments.

[0138] refer to Figure 9 The diagram shows a structural schematic of the sixth embodiment of the frequency modulation light source disclosed herein.

[0139] It should be noted that, Figure 9 The structures of the lasers and photoelectric conversion circuits in some of the embodiments shown can be the same as those in the aforementioned embodiments.

[0140] In some embodiments of this disclosure, the practice of setting the first modulator as an IQ modulator is also applicable to the feedforward scheme.

[0141] In some embodiments of this disclosure, the second beam splitter 525 can split the received initial light or initial frequency-modulated light into a first optical signal and a third optical signal. The first modulator that can be set in the third optical signal path can be set as an IQ modulator to modulate the third optical signal before outputting it.

[0142] like Figure 9 As shown, the first modulator 523, connected in the downstream optical path of the delayer 550, is configured as an IQ modulator. The signal generation circuit 522, connected to the frequency modulation circuit 530, is connected between the photoelectric conversion circuit 5212 and the first modulator 523.

[0143] Moreover, as Figure 9 As shown, in the feedforward scheme, the signal generation circuit 522 can amplify and couple the reference signal with the electrical signal generated by the balanced detection result. The resulting phase modulator signal can not only eliminate phase noise but also frequency modulate the transmitted optical signal. The frequency discriminator 5211 receives fixed-frequency light, eliminating the need for a second modulator. The first modulator 523 performs linewidth compression while also achieving frequency modulation.

[0144] In some embodiments, the frequency-modulated light source further includes a signal demultiplexer. The signal demultiplexer 523a may be the same as or similar to the signal demultiplexer 423a. For example, the signal demultiplexer 523a is a 90° bridge connected between the signal generation circuit 522 and the first modulator 523.

[0145] refer to Figure 10 The diagram shows a structural schematic of the seventh embodiment of the frequency modulation light source disclosed herein.

[0146] It should be noted that, Figure 10 The structures of the lasers and photoelectric conversion circuits in some of the embodiments shown can be the same as those in the aforementioned embodiments.

[0147] In some embodiments of this disclosure, the frequency-modulated light source may include: a plurality of lasers, which can generate a plurality of initial lights in a time-division manner; the difference in the center wavelength of the initial lights generated by different lasers may be an integer multiple of the frequency discrimination period, wherein the frequency discrimination period is the period during which the amplitude of the second optical signal changes with the frequency of the first optical signal.

[0148] Multiple lasers can share a single frequency discriminator through time-division multiplexing. Furthermore, the relationship between the discriminator's transmittance and the frequency of the transmitted optical signal is periodic, with the period during which the amplitude of the second optical signal changes with the frequency of the first optical signal being the discriminator's frequency period. Making the difference in the center wavelengths of the light emitted by different lasers an integer multiple of the frequency discriminator's frequency period ensures that the light emitted by all lasers can be matched to the frequency of the discriminator's operating point.

[0149] For example, such as Figure 10 As shown, the input terminal of the first modulator 623 is connected to the output terminals of the plurality of lasers 610 to receive the initial light generated by all lasers 610. The plurality of lasers 610 are all connected to the frequency modulation circuit 630, and each laser 610 generates initial light of a different wavelength under the control of a reference signal.

[0150] Figure 10 The frequency-modulated light source shown employs a feedback scheme. The first beam splitter 624 splits the light modulated by the first modulator 623 into an outgoing light and a first optical signal; the frequency discriminator 6211 generates a second optical signal based on the first optical signal, converting the frequency information of the first optical signal into the intensity information of the second optical signal; the photoelectric conversion circuit 6212 performs photoelectric conversion on the second optical signal to generate an electrical signal reflecting the intensity information of the second optical signal, which is then integrated by the integrator circuit 6221 of the signal generation circuit 622 to form a phase-modulated signal, which is then provided to the first modulator 623; the first modulator 623 further modulates subsequent light rays.

[0151] It should be noted that in some embodiments, multiple initial lights are generated by multiple lasers. In other embodiments, the lasers of the frequency-modulated light source can also generate multiple initial lights of different wavelengths in a time-division manner; the lasers generate multiple initial lights of different wavelengths in a time-division manner, and the difference in the center wavelength of the initial lights of different wavelengths is an integer multiple of the frequency discrimination period, wherein the frequency discrimination period is the period during which the amplitude of the second optical signal changes with the frequency of the first optical signal.

[0152] It should also be noted that, Figure 10 The frequency-modulated light source shown employs a feedback scheme. In other embodiments of the present invention, the frequency-modulated light source that generates multiple initial lights of different wavelengths can also employ a feedforward scheme, that is, the received light is divided into a first optical signal and a third optical signal by a second beam splitter; the first signal light is converted by a conversion circuit and a signal generation circuit to generate a phase-modulated signal; and the third optical signal is modulated by a first modulator for emission.

[0153] In other embodiments of the present invention, the frequency-modulated light source may further include an electro-optic modulator to modulate the fixed-frequency light generated by the laser to obtain frequency-modulated light. In some embodiments, the electro-optic modulator may include a phase modulator, an IQ modulator, a semiconductor optical amplifier, or an acousto-optic modulator.

[0154] For example, such as Figure 11 As shown. The frequency-modulated light source includes a laser component 701, which includes a laser 710 and an electro-optic modulator 711. The electro-optic modulator 711 is located in the optical path downstream of the laser 710. The laser 710 can generate fixed-frequency light; the electro-optic modulator 711 receives the fixed-frequency light generated by the laser 710 and modulates the fixed-frequency light to obtain frequency-modulated light.

[0155] The linewidth compression circuit 720 is located in the optical path downstream of the laser component 701. Specifically, the input terminal of the linewidth compression circuit 720 is connected to the output terminal of the electro-optic modulator 711, receiving and modulating the frequency-modulated light to compress the linewidth. Furthermore, in the frequency-modulated light source, the linewidth compression circuit can be integrated onto a silicon photonics chip to improve integration density.

[0156] In other embodiments of the present invention, the frequency-modulated light source may further include an optical phase-locked loop (PLL). The PLL is connected to a laser and can pre-correct the frequency of the initial light generated by the laser. A linewidth compression circuit can further narrow the linewidth of the pre-corrected initial light, thereby compressing the linewidth of the frequency-modulated light source and improving the frequency modulation linearity.

[0157] Accordingly, the present invention also provides a launching assembly.

[0158] The transmitting component includes: a frequency-modulated light source, the frequency-modulated light source including: a laser and a linewidth compression circuit; the laser is configured to generate initial light; the linewidth compression circuit is configured to receive a first optical signal, the first optical signal including at least a portion of the initial light or initial frequency-modulated light formed by modulating the initial light; the linewidth compression circuit is further configured to transmit the first optical signal and convert the frequency information of the first optical signal into the light intensity information of a second optical signal; the linewidth compression circuit is further configured to obtain the frequency noise of the initial light according to the second optical signal to generate a phase modulation signal; the linewidth compression circuit is further configured to modulate the transmitted optical signal according to the phase modulation signal and output it to form emitted light.

[0159] In some embodiments of this disclosure, the frequency-modulated light source is the frequency-modulated light source of this invention. Specific technical solutions for the frequency-modulated light source are described in the foregoing embodiments. Further details are omitted here. The linewidth compression circuit modulates the transmitted optical signal based on a phase modulation signal, resulting in a larger feedback loop bandwidth. This leads to narrower linewidth light generated by the frequency-modulated light source and higher frequency modulation linearity, thus improving the performance of the constructed transmitting component.

[0160] In some embodiments of this disclosure, the emitting assembly further includes at least one lens located in the optical path downstream of the emitted light, the at least one lens being configured to shape the emitted light.

[0161] In addition, this disclosure also provides a lidar.

[0162] The lidar includes: a transmitting component, the transmitting component including: a frequency-modulated light source, the frequency-modulated light source including: a laser and a linewidth compression circuit; the laser is configured to generate initial light; the linewidth compression circuit is configured to receive a first optical signal, the first optical signal including at least a portion of the initial light or initial frequency-modulated light formed by modulating the initial light; the linewidth compression circuit is further configured to transmit the first optical signal and convert the frequency information of the first optical signal into the light intensity information of a second optical signal; the linewidth compression circuit is further configured to obtain the frequency noise of the initial light according to the second optical signal to generate a phase modulation signal; the linewidth compression circuit is further configured to modulate the transmitted optical signal according to the phase modulation signal and output it to form emitted light; the emitted light is reflected by an object to form echo light; and a receiving component, the receiving component being configured to receive the echo light.

[0163] In some embodiments disclosed herein, the transmitting component is the transmitting component of the present invention. Specific technical solutions for the transmitting component are described in the foregoing embodiments of the transmitting component. Further details of the present invention will not be repeated here.

[0164] In some embodiments of this disclosure, the lidar is a frequency-modulated continuous wave lidar. After receiving the echo light, the lidar couples the echo light and the local oscillator light separated from the emitted light to coherently form coherent light for detection. The frequency-modulated light source in the transmitting component produces a narrower linewidth and higher frequency modulation linearity, enabling the laser to achieve higher precision, faster speed, and longer distance laser detection.

[0165] In summary, the linewidth compression circuit of the frequency-modulated light source converts the frequency information of the first optical signal into the intensity information of the second optical signal, and thereby generates a phase modulation signal. The linewidth compression circuit also modulates the transmitted optical signal according to the phase modulation signal before outputting it. Because the linewidth compression circuit modulates the transmitted optical signal according to the phase modulation signal before outputting it, the feedback loop bandwidth is larger, greatly improving the performance of the frequency-modulated light source.

[0166] It should be understood that the division of modules and units in the above system is only a logical functional division. In actual implementation, there may be other division methods. In actual implementation, they may be fully or partially integrated into a single physical entity, or they may be physically separated. Furthermore, the modules and units in the device can be implemented by a processor calling software; for example, the device includes a processor connected to memory, which stores instructions. The processor calls the instructions stored in memory to implement any of the above methods or to implement the functions of each module and unit of the device. The processor may be a general-purpose processor, such as a central processing unit (CPU) or a microprocessor, and the memory may be internal or external to the system. Alternatively, the modules and units in the device can be implemented in the form of hardware circuits. The functionality of some or all modules can be achieved through the design of these hardware circuits, which can be understood as one or more processors. For example, in one implementation, the hardware circuit is an application-specific integrated circuit (ASIC), and the functionality of some or all of the above modules is achieved through the design of the logical relationships between the components within the circuit. In another implementation, the hardware circuit can be implemented using a programmable logic device (PLD), which can include a large number of logic gates. The logical relationships between these logic gates are configured through configuration files, thereby achieving the functionality of some or all of the above modules. All modules of the above system can be implemented entirely through processor-invoked programs, entirely through hardware circuits, or partially through processor-invoked programs with the remaining parts implemented through hardware circuits.

[0167] While the above disclosure is provided, it is not limited thereto. Any person skilled in the art may make various alterations and modifications without departing from the spirit and scope of this disclosure; therefore, the scope of protection of this disclosure shall be determined by the scope defined in the claims.

Claims

1. A frequency-modulated light source, characterized in that, include: Laser and linewidth compression circuit; The laser is configured to generate initial light; The linewidth compression circuit is configured to receive a first optical signal, the first optical signal including at least a portion of the initial light or initial frequency-modulated light formed by modulating the initial light; the linewidth compression circuit is also configured to transmit the first optical signal and convert the frequency information of the first optical signal into the light intensity information of a second optical signal; the linewidth compression circuit is also configured to generate a phase modulation signal based on the second optical signal. The linewidth compression circuit is further configured to modulate the transmitted optical signal according to the phase modulation signal and then output it. The linewidth compression circuit includes: a conversion circuit configured to transmit the first optical signal, convert the frequency information of the first optical signal into the light intensity information of the second optical signal, and convert the second optical signal into an electrical signal; the conversion circuit includes: a frequency discriminator configured to transmit the first optical signal and output the second optical signal; and a second modulator configured to modulate the frequency of the operating point of the frequency discriminator according to a reference signal so that the frequency of the operating point of the frequency discriminator is equal to the center frequency of the initial light.

2. The frequency-modulated light source as described in claim 1, characterized in that, The linewidth compression circuit further includes: a signal generation circuit and a first modulator; The input terminal of the signal generation circuit is connected to the output terminal of the conversion circuit, and is configured to receive the electrical signal and output the phase modulation signal; The first modulator is configured to modulate the transmitted optical signal according to the phase modulation signal and then output it.

3. The frequency-modulated light source as described in claim 2, characterized in that, The conversion circuit further includes: a photoelectric conversion circuit; The photoelectric conversion circuit is configured to receive the second optical signal and output an electrical signal reflecting the light intensity information.

4. The frequency-modulated light source as described in claim 1, characterized in that, The frequency discriminator includes at least one of the following: a Mach-Zehnder interferometer, a fiber Bragg grating, a bandpass filter, and a microring.

5. The frequency-modulated light source as described in claim 3, characterized in that, The photoelectric conversion circuit is configured to separate at least a first sub-signal and a second sub-signal from the second optical signal, and is further configured to convert the first sub-signal into a first electrical signal and the second sub-signal into a second electrical signal, respectively. The signal generation circuit generates a phase modulation signal based on the first electrical signal and the second electrical signal.

6. The frequency-modulated light source as described in claim 5, characterized in that, The photoelectric conversion circuit is further configured to extract a third sub-signal from the second optical signal and convert the third sub-signal into a third electrical signal. The frequency-modulated light source further includes a center frequency feedback circuit, configured to generate a center frequency feedback signal based on the third electrical signal and provide it to the laser or the second modulator in the conversion circuit.

7. The frequency-modulated light source as described in claim 2, characterized in that, The first modulator is configured to receive the initial light or the initial frequency-modulated light, and modulate the initial light or the initial frequency-modulated light based on the phase modulation signal before outputting it; The linewidth compression circuit further includes a first beam splitter, the input of which is connected to the first modulator, the first output of which outputs the first optical signal, and the second output of which outputs outgoing light.

8. The frequency-modulated light source as described in claim 2, characterized in that, The frequency-modulated light source further includes a second beam splitter. The input end of the second beam splitter receives the initial light or the initial frequency-modulated light. The first output end of the second beam splitter outputs the first optical signal, and the second output end of the second beam splitter outputs a third optical signal. The input end of the first modulator is connected to the second output end of the second beam splitter. The first modulator is configured to modulate the third optical signal based on the phase modulation signal and then output outgoing light.

9. The frequency-modulated light source as described in claim 8, characterized in that, The frequency-modulated light source further includes a delay unit, the input of which is connected to the second output of the second beam splitter, and the output of which is connected to the input of the first modulator.

10. The frequency-modulated light source as described in claim 2, characterized in that, The first modulator includes at least one of a phase modulator, an IQ modulator, a semiconductor optical amplifier, and an acousto-optic modulator.

11. The frequency-modulated light source as described in claim 2, characterized in that, When the initial light is frequency-modulated light, or when the linewidth compression circuit receives the initial frequency-modulated light, the signal generation circuit includes an integrator circuit configured to receive the electrical signal and output the phase-modulated signal.

12. The frequency-modulated light source as described in claim 2, characterized in that, The initial light is fixed-frequency light, and the first modulator includes an IQ modulator; the signal generation circuit includes an electrical signal coupler, which is configured to output the phase modulation signal. The IQ modulator modulates the transmitted optical signal according to the phase modulation signal and outputs frequency-modulated light.

13. The frequency-modulated light source as described in claim 12, characterized in that, The electrical signal coupler includes a voltage-controlled oscillator.

14. The frequency-modulated light source as described in claim 1, characterized in that, The frequency-modulated light source includes: multiple lasers, which generate multiple initial lights in a time-division manner; The difference in the center wavelength of the initial light generated by different lasers is an integer multiple of the frequency discrimination period, where the frequency discrimination period is the period during which the amplitude of the second optical signal changes with the frequency of the first optical signal.

15. The frequency-modulated light source as described in claim 1, characterized in that, The laser generates multiple initial lights of different wavelengths in a time-division manner. The difference in the center wavelength of the initial lights of different wavelengths is an integer multiple of the frequency discrimination period, where the frequency discrimination period is the period during which the amplitude of the second optical signal changes with the frequency of the first optical signal.

16. A transmitting assembly, characterized in that, include: A frequency-modulated light source, comprising: a laser and a linewidth compression circuit; the laser is configured to generate initial light; the linewidth compression circuit is configured to receive a first optical signal, the first optical signal including at least a portion of the initial light or initial frequency-modulated light formed by modulating the initial light; the linewidth compression circuit is further configured to transmit the first optical signal and convert the frequency information of the first optical signal into the intensity information of a second optical signal; the linewidth compression circuit is further configured to obtain the frequency noise of the initial light based on the second optical signal to generate a phase modulation signal; the linewidth compression circuit is further configured to modulate the transmitted optical signal according to the phase modulation signal and output it to form emitted light, the linewidth compression circuit comprising: a conversion circuit, the conversion circuit being configured to transmit the first optical signal, convert the frequency information of the first optical signal into the intensity information of the second optical signal, and convert the second optical signal into an electrical signal; the conversion circuit comprising: a frequency discriminator, the frequency discriminator being configured to transmit the first optical signal and output the second optical signal; and a second modulator, the second modulator being configured to modulate the frequency of the operating point of the frequency discriminator according to a reference signal so that the frequency of the operating point of the frequency discriminator is equal to the center frequency of the initial light.

17. The launching assembly as claimed in claim 16, characterized in that, Also includes: At least one lens is located in the optical path downstream of the emitted light, and the at least one lens is configured to shape the emitted light.

18. A lidar, characterized in that, include: A transmitting assembly includes: a frequency-modulated light source, the frequency-modulated light source including: a laser and a linewidth compression circuit; the laser is configured to generate initial light; the linewidth compression circuit is configured to receive a first optical signal, the first optical signal including at least a portion of the initial light or initial frequency-modulated light formed by modulating the initial light; the linewidth compression circuit is further configured to transmit the first optical signal and convert the frequency information of the first optical signal into the light intensity information of a second optical signal; the linewidth compression circuit is further configured to obtain the frequency noise of the initial light based on the second optical signal to generate a phase-modulated signal; the linewidth compression circuit is further configured to... According to the phase modulation signal, the transmitted optical signal is modulated and output to form emitted light. The linewidth compression circuit includes: a conversion circuit configured to transmit the first optical signal, convert the frequency information of the first optical signal into the light intensity information of the second optical signal, and convert the second optical signal into an electrical signal; the conversion circuit includes: a frequency discriminator configured to transmit the first optical signal and output the second optical signal; and a second modulator configured to modulate the frequency of the operating point of the frequency discriminator according to a reference signal so that the frequency of the operating point of the frequency discriminator is equal to the center frequency of the initial light. The emitted light is reflected by the object to form an echo light; A receiving component configured to receive the echo light.

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