Frequency modulation light source, transmitting assembly and laser radar

Abstract

The invention provides a frequency-modulated light source, a transmitting assembly and a laser radar. The frequency-modulated light source comprises a laser and a line width compression circuit. The laser is configured to generate initial light; the line width compression circuit is configured to receive a first optical signal, and the first optical signal comprises at least part of initial light or initial frequency modulation light formed by modulating the initial light; the line width 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 the second optical signal; the line width compression circuit is further configured to generate a phase modulation signal according to the second optical signal; the line width compression circuit is further configured to modulate the transmitted optical signal according to the phase modulation signal and then output the modulated optical signal. The line width compression circuit modulates the transmitted optical signal according to the phase modulation signal and then outputs the modulated optical signal, the bandwidth of a feedback loop is larger, and the performance of the frequency modulation light source is greatly improved.

Description

Technical Field

[0001] The present disclosure relates to laser detection, and in particular to a frequency modulated light source, a transmitting assembly and a laser radar. Background Art

[0002] For lasers, the linewidth of the emitted light is a key performance indicator. When used for measurement, the smaller the laser linewidth (full width at half maximum of the emission spectrum), the better the range and distance measurement accuracy. Frequency-modulated light sources are crucial in numerous applications, including lidar, optical frequency domain reflectometry, 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 solved by the present disclosure is how to improve the output linewidth and output linearity of a frequency modulated light source.

[0006] To solve the above problems, the present 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, which includes 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 light intensity information of a second optical signal; the linewidth compression circuit is further configured to generate a phase modulation signal based on the second optical signal; and the linewidth compression circuit is further configured to modulate the transmitted optical signal based on the phase modulation signal and output it.

[0008] Optionally, the linewidth compression circuit includes: a conversion circuit, a signal generating 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 end of the signal generating circuit is connected to the output end of the conversion circuit, 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 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 discriminator according to a reference signal so that the frequency of the operating point of the discriminator is equal to the center frequency of the initial light.

[0012] Optionally, the optoelectronic 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 generating circuit generates a phase modulation signal based on the first electrical signal and the second electrical signal.

[0013] Optionally, the optoelectronic conversion circuit is further configured to separate 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 and then output the modulated light; the linewidth compression circuit also includes a first optical splitter, the input end of the first optical splitter is connected to the first modulator, the first output end of the first optical splitter outputs the first optical signal, and the second output end of the first optical splitter outputs the outgoing light.

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

[0016] Optionally, the frequency modulated light source further includes: a delay device, wherein the input end of the delay device is connected to the second output end of the second optical splitter, and the output end of the delay device is connected to the input end 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 the linewidth compression circuit receives initial frequency modulated light, the signal generating circuit includes: an integration circuit, and the integration circuit is 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 generating circuit includes an electrical signal coupler, and the electrical signal coupler is configured to output the phase-modulated signal; the IQ modulator modulates the transmitted optical signal according to the phase-modulated signal to output 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-sharing manner; the difference in central wavelengths of the initial lights generated by different lasers is an integer multiple of a demodulation period, where the demodulation period is the period in 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-sharing manner, and the difference between the center wavelengths of the initial lights of different wavelengths is an integer multiple of a demodulation period, where the demodulation period is the period in which the amplitude of the second optical signal changes with the frequency of the first optical signal.

[0023] Correspondingly, the present disclosure also provides a transmitting component, comprising: a frequency-modulated light source, 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 a portion of the initial light or initial frequency-modulated light formed by modulation of 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 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 modulate the transmitted optical signal based on the phase-modulated signal and output it to form an output light.

[0024] Optionally, it further includes: at least one lens, wherein the at least one lens is located in the optical path downstream of the emergent light, and the at least one lens is configured to shape the emergent light.

[0025] In addition, the present disclosure also provides a laser radar, including: 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 light signal, the first light signal including at least part of the initial light or initial frequency-modulated light formed by modulation of the initial light; the linewidth compression circuit is also configured to transmit the first light signal and convert the frequency information of the first light signal into light intensity information of a second light signal; the linewidth compression circuit is also configured to obtain the frequency noise of the initial light based on the second light signal to generate a phase-modulated signal; the linewidth compression circuit is also configured to modulate the transmitted light signal based on the phase-modulated signal and output it to form an outgoing light; the outgoing light forms an echo light after being reflected by an object; a receiving component, the receiving component is configured to receive the echo light.

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

[0027] In the disclosed technical solution, the linewidth compression circuit of the frequency-modulated light source converts the frequency information of a first optical signal into the light intensity information of a second optical signal, thereby generating a phase-modulated signal. The linewidth compression circuit is further configured to modulate the transmitted optical signal according to the phase-modulated signal and then output it. This modulation and output of the transmitted optical signal according to the phase-modulated signal results in a wider feedback loop bandwidth, significantly improving the performance of the frequency-modulated light source. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present disclosure or the technical solutions in the prior art, the following briefly introduces the drawings required for the embodiments or the description of the prior art. Obviously, the drawings described below are only embodiments of the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without creative work. The drawings are used to provide a further understanding of the present disclosure and constitute part of the specification. Together with the embodiments of the present disclosure, they are used to explain the present disclosure and do not constitute a limitation of the present disclosure. In the drawings:

[0029] Figure 1 shows a functional block diagram of the first embodiment of the frequency modulated light source disclosed herein;

[0030] Figure 2 Shown Figure 1 A schematic structural diagram of an embodiment of a frequency modulated light source is shown;

[0031] Figure 3 Shown Figure 1 A schematic diagram of the change in frequency of the first optical signal input to the frequency discriminator over time in the embodiment of the frequency modulated light source shown;

[0032] Figure 4 Shown Figure 1 A schematic diagram of the change in the intensity of the second optical signal output by the frequency discriminator over time in the embodiment of the frequency modulated light source shown;

[0033] Figure 5 shows a structural schematic diagram of a second embodiment of the frequency modulated light source disclosed herein;

[0034] Figure 6 shows a schematic structural diagram of a third embodiment of the frequency modulated light source disclosed herein;

[0035] Figure 7 shows a structural schematic diagram of a fourth embodiment of the frequency modulated light source disclosed herein;

[0036] Figure 8 shows a structural schematic diagram of the fifth embodiment of the frequency modulated light source disclosed in the present invention;

[0037] Figure 9 shows a structural schematic diagram of a sixth embodiment of the frequency modulated light source disclosed herein;

[0038] Figure 10 shows a structural schematic diagram of the seventh embodiment of the frequency modulated light source disclosed in the present invention;

[0039] Figure 11 A structural schematic diagram of the eighth embodiment of the frequency-modulated light source disclosed in the present invention is shown. DETAILED DESCRIPTION

[0040] Hereinafter, only certain exemplary embodiments are briefly described. As will be appreciated by those skilled in the art, the described embodiments may be modified in various ways without departing from the spirit or scope of the present disclosure. Therefore, the drawings and description are to be considered as illustrative in nature and not restrictive.

[0041] In the description of the present disclosure, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present disclosure and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present disclosure. In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the said features. In the description of the present disclosure, "multiple" means two or more, unless otherwise clearly and specifically defined.

[0042] In the description of this disclosure, it should be noted that, unless otherwise expressly specified or limited, the terms "installed," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections, electrical connections, or interconnected connections; they can refer to direct connections or indirect connections through an intermediate medium; they can refer to internal communication between two components or the interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in this disclosure based on specific circumstances.

[0043] In the present disclosure, unless otherwise expressly specified or limited, a first feature being "above" or "below" a second feature may include the first and second features being in direct contact, or may include the first and second features being in contact not directly but through another feature between them. Moreover, a first feature being "above," "above," and "above" a second feature includes the first feature being directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below," "below," and "below" a second feature includes the first feature being directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0044] The disclosure below provides many different embodiments or examples for realizing different structures of the present disclosure. In order to simplify the disclosure of the present disclosure, the components and settings of specific examples are described below. Of course, they are merely examples and are not intended to limit the present disclosure. In addition, the present disclosure may repeat reference numbers and / or reference letters in different examples, and such repetition is for the purpose of simplicity and clarity and does not in itself indicate the relationship between the various embodiments and / or settings discussed. In addition, the present disclosure provides examples of various specific processes and materials, but those of ordinary skill in the art will appreciate the application of other processes and / or the use of other materials.

[0045] As can be seen from the background art, the frequency modulated light source in the prior art has the problem that the output line width and output linearity are not ideal.

[0046] There are two main methods for frequency-modulated light source sweeping. One is external modulation, where a laser emits fixed-frequency light and an electro-optical modulator superimposes an RF signal on it to achieve frequency modulation. This external modulation method has a low level of integration and requires an external cavity laser, a narrow-linewidth laser (approximately 10kHz), which is very expensive. Furthermore, the mode-hopping characteristics of the external cavity laser can lead to unstable operation of the FM light source.

[0047] The other is direct modulation, which changes the operating current of the laser 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) to achieve frequency modulation. However, the linewidth of a DFB is very wide (about 100kHz), and an optoelectronic phase-locked loop or frequency discriminator is required to compress the linewidth and optimize the frequency modulation linearity. However, due to the slow response of the laser, the bandwidth of the feedback loop is very narrow (generally less than 1MHz), which will cause the residual frequency noise to be large, thus affecting the measurement accuracy.

[0048] To solve the technical problem, the present disclosure provides a frequency modulated light source, which may include: a laser and a linewidth compression circuit; the laser may generate initial light;

[0049] The linewidth compression circuit 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 can also transmit the first optical signal and convert the frequency information of the first optical signal into light intensity information of a second optical signal; the linewidth compression circuit can also generate a phase modulation signal based on the second optical signal; and the linewidth compression circuit can also modulate the transmitted optical signal based on the phase modulation signal and output it.

[0050] In the disclosed technical solution, the linewidth compression circuit of the frequency-modulated light source can convert the frequency information of a first optical signal into the light intensity information of a second optical signal, thereby generating a phase-modulated signal. The linewidth compression circuit can also modulate the transmitted optical signal according to the phase-modulated signal and output it. This linewidth compression circuit can modulate the transmitted optical signal according to the phase-modulated signal and output it, thereby increasing the feedback loop bandwidth and significantly improving the performance of the frequency-modulated light source.

[0051] In order to make the above-mentioned objects, features and advantages of the present disclosure more obvious and easy to understand, specific embodiments of the present disclosure are described in detail below with reference to the accompanying drawings.

[0052] refer to Figure 1 and Figure 2 ,in Figure 1 shows a functional block diagram of the first embodiment of the frequency modulated light source disclosed herein; Figure 2 Shown Figure 1 The figure shows a schematic structural diagram of an embodiment of a frequency modulated light source disclosed herein.

[0053] 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 can 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 light 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; and the linewidth compression circuit 120 can also modulate the transmitted optical signal based on the phase modulation signal and output it.

[0054] The specific technical solutions of the frequency modulated light source embodiments of the present disclosure are described in detail below with reference to the accompanying drawings.

[0055] The laser is used to generate light.

[0056] In some embodiments of the present disclosure, the laser may be a distributed feedback laser (DFB).

[0057] In some embodiments, the laser may be a fixed-frequency laser, and the initial light generated by the laser may be fixed-frequency light. In other embodiments of the present disclosure, the laser may be modulated by an electric current, and the initial light generated by the laser may also be frequency-modulated light. In other embodiments of the present disclosure, the initial light generated by the laser may be fixed-frequency light, and the frequency-modulated light source may further include an electro-optical modulator to modulate the fixed-frequency light to obtain frequency-modulated light.

[0058] It should be noted that the frequency-modulated light source may further include: a frequency-modulation circuit, and the frequency-modulation circuit may generate a reference signal for frequency modulation.

[0059] 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 laser's output frequency can have a fixed relationship with the current: the greater the current, the lower the output frequency. A drive current can be generated based on the reference signal, with the current varying with the amplitude of the reference signal, thereby varying the laser's output frequency to achieve frequency modulation. In specific implementations, the amplitude of the reference signal and the corresponding laser's output frequency vary linearly over time, and the variation pattern can take the form of a sawtooth wave, a triangular wave, a trapezoidal wave, or the like.

[0060] In some other embodiments, the frequency modulation circuit can be connected to an electro-optical modulator so that the modulation signal of the electro-optical modulator corresponds to a reference signal. The electro-optical modulator frequency modulates the fixed-frequency light output by the laser, thereby controlling the frequency of the frequency-modulated light to change over time corresponding to the amplitude change of the reference signal.

[0061] For example, 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, changes the current of the laser 110 to change the frequency of the light generated by the laser 110, and realizes frequency modulation.

[0062] The linewidth compression circuit is used for modulating the transmitted optical signal to compress the linewidth.

[0063] In some embodiments of the present disclosure, the linewidth compression circuit may include: a conversion circuit, a signal generating 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 end of the signal generating circuit can be connected to the output end 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.

[0064] The conversion circuit can convert frequency information of the first optical signal into light intensity information of the second optical signal, and can convert the second optical signal into an electrical signal.

[0065] In some embodiments, the conversion circuit may include: a frequency discriminator and a photoelectric conversion circuit; the frequency discriminator can transmit the first optical signal and output the second optical signal; the photoelectric conversion circuit can receive the second optical signal and output an electrical signal reflecting the light intensity information.

[0066] The frequency discriminator can transmit the first optical signal and generate a second optical signal according to 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.

[0067] The discriminator can be an optical discriminator. An optical discriminator is an optical component whose output optical signal intensity corresponds to the frequency of the input optical signal. A curve representing the relationship between the intensity of the optical signal output by the optical discriminator and the frequency of the input optical signal is the discriminator's frequency-intensity curve. The discriminator is highly sensitive to changes in the frequency of the transmitted optical signal. A slight 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 discriminator.

[0068] When the frequency of the initial light generated by the laser fluctuates, the linewidth of the laser increases. When the frequency of the initial light fluctuates, the frequency of a first optical signal, including at least a portion of the initial light or initial frequency-modulated light formed by modulating the initial light, also fluctuates. The frequency discriminator can convert the frequency jitter of the first optical signal into a change in the intensity of a second optical signal.

[0069] The frequency discriminator has an operating point. The operating point of the frequency discriminator is located at the half-maximum width of the frequency intensity curve of the frequency discriminator. When the frequency of the input optical signal is at the operating point, the jitter of the frequency of the input optical signal is in a linear section. The jitter of the frequency of the first optical signal linearly causes the jitter of the intensity of the second optical signal, such as Figure 3 and Figure 4 shown.

[0070] In some embodiments, the frequency discriminator may include at least one of: a Mach-Zehnder interferometer, a fiber Bragg grating, a bandpass filter, and a microring. For example, Figure 2 As shown, the discriminator 1211 is a Mach-Zehnder interferometer. The discriminator 1211 includes a spectrometer spa, the input end of which is suitable for inputting a first optical signal. The spectrometer spa splits the first optical signal into two analysis signals, which are output from the two output ends of the spectrometer spa to the two arms (optical paths) of the Mach-Zehnder interferometer. In the Mach-Zehnder interferometer, 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. The optical path difference between the optical paths transmitting different analysis signals causes a phase difference between the two analysis signals when combined. The intensity of the second optical signal formed by the combined beam is related to the phase difference between the analysis signals.

[0071] The frequency-intensity curve of the Mach-Zehnder interferometer varies in a sine-square or cosine-square manner. 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 is the half-width at half maximum of the transmission peak, c is the speed of light, n is the refractive index, and L is the arm length difference. For example, when the arm length difference is 0.5m, the half-width at half maximum of the transmission peak corresponding to a wavelength of 1555nm is approximately 200MHz.

[0072] In some embodiments, the conversion circuit may further include: a second modulator, which may modulate the frequency of the operating point of the discriminator according to a reference signal so that the frequency of the operating point of the discriminator is equal to the center frequency of the initial light.

[0073] The second modulator can modulate the operating point frequency of the discriminator to form a discriminator with an adjustable operating point frequency, so that the operating point frequency of the discriminator is equal to the operating frequency of the initial light, thereby suppressing external low-frequency disturbances, making the discriminator operate in a linear section, and making the jitter of the second optical signal intensity linearly reflect the jitter of the first optical signal frequency.

[0074] 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.

[0075] For example, Figure 2 As shown, the frequency discriminator 1211 is a Mach-Zehnder interferometer. The second modulator 1213 includes a phase modulator, which is located in an 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.

[0076] It should be noted that in other embodiments, the discriminator may also be a fiber Bragg grating, a bandpass filter, or a microring. As the discriminator changes, the second modulator also changes accordingly. For example, the discriminator is a fiber Bragg grating having a thermally tuned phase shift region. The second modulator may include a temperature control element that can change the temperature of the thermally tuned phase shift region to change the refractive index. The discriminator may be a microring. The second modulator may include a modulation circuit that can generate a refractive index modulation signal that can change the refractive index of the microring.

[0077] It should also be noted that the reference signal is generated by a frequency modulation circuit. For example, 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 .

[0078] The conversion circuit 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 reflecting light intensity information of the second optical signal.

[0079] 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. The electrical signal generated by the photoelectric conversion circuit can also reflect the frequency information of the first optical signal.

[0080] 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.

[0081] The first sub-signal and the second sub-signal can be detected in a balanced manner to obtain the phase noise of the first optical signal, which can offset the light intensity noise of the initial light generated by the laser and the noise caused by environmental jitter, thereby eliminating the influence of the jitter of the light intensity of the initial light generated by the laser and the environmental jitter on the light intensity information of the second optical signal, thereby achieving linewidth compression and suppressing nonlinear phase errors in the frequency modulation process.

[0082] For example, 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.

[0083] In addition, in some embodiments, the photoelectric conversion circuit can further separate 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 can further 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.

[0084] The third electrical signal can stabilize the operating point of the discriminator, so that the center frequency of the first optical signal always matches the operating frequency of the discriminator, thereby suppressing low-frequency disturbances. The center frequency feedback signal is used to ensure that the center frequency of the first optical signal always matches the operating frequency of the discriminator.

[0085] like Figure 2 As 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; and the center frequency feedback circuit 140 is connected to the second modulator 1213 so that the frequency of the operating point of the discriminator moves as the center frequency of the first optical signal moves.

[0086] 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 load them to the second modulator.

[0087] For example, Figure 2 As shown, the two input ends of the adder 1214 are respectively connected to the frequency modulation circuit 130 and the center frequency feedback circuit 140, receiving the reference signal and the center frequency feedback signal from the frequency modulation circuit 130 and the center frequency feedback circuit 140 for coupling. The output end of the adder 1214 is connected to the second modulator, and the coupling result is applied to the second modulator. The operating point of the discriminator provided with the second modulator is adjustable. As the signal applied to the second modulator changes, the operating point of the discriminator moves in the frequency domain. A V π A change in voltage can shift half the Free Spectral Range (FSR).

[0088] In some embodiments, the photoelectric conversion circuit can separate the first sub-signal, the second sub-signal and the third sub-signal from the second optical signal by multiple splitting. Figure 2 As shown, the photoelectric conversion circuit 1212 also includes: a primary optical splitter SP1 and two secondary optical splitters SP2, wherein the input end of the primary optical splitter SP1 is connected to the output end of the discriminator 1211 to receive the second optical signal output by the discriminator 1211, and the two output ends of the primary optical splitter SP1 are respectively connected to the input ends of the two secondary optical splitters SP2. The primary optical splitter SP1 splits the second optical signal into two preliminary signals and outputs them to the two secondary optical splitters SP2 respectively; the secondary optical splitter SP2 splits the preliminary signal into two sub-signals to output them to different detectors, one output end of one of the secondary optical splitters SP2 is connected to the first detector PD1 to achieve reception and conversion of the first sub-signal, one output end of the other secondary optical splitter SP2 is connected to the second detector PD2 to achieve reception and conversion of the second sub-signal, and the other output end of one of the two secondary optical splitters SP2 is connected to the third detector PD3 to achieve reception and conversion of the third sub-signal.

[0089] It should be noted that if Figure 2As shown, in some embodiments, the photoelectric conversion circuit 1212 further includes a fourth detector PD4, connected to the other output terminal of the other of the two secondary optical splitters SP2, to receive the split fourth sub-signal to prevent 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 upon receiving the fourth sub-signal is suitable for balance point detection.

[0090] It should also be noted that, in some embodiments, the optoelectronic conversion circuit separates the first sub-signal, the second sub-signal and the third sub-signal from the second optical signal by multiple equal divisions, and the splitting ratios of the first-level splitter SP1 and the second-level splitter SP2 are both 1:1. For example, the first-level splitter SP1 and the second-level splitter SP2 are both 1:1 optical couplers.

[0091] The signal generating circuit may be connected to the conversion circuit, may receive the electrical signal generated by the conversion circuit after converting the second optical signal, and may output the phase modulation signal according to the electrical signal.

[0092] In some embodiments, the photoelectric conversion circuit in the conversion circuit can separate the first sub-signal and the second sub-signal from the second optical signal and convert them into the first electrical signal and the second electrical signal respectively for balanced detection; the signal generating circuit can generate a phase modulation signal based on the first electrical signal and the second electrical signal.

[0093] For example, Figure 2 As 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 for balanced detection, and the electrical signal obtained by the signal generating 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.

[0094] In some embodiments, the initial light is frequency modulated light, or when the linewidth compression circuit receives the initial frequency modulated light, the signal generating circuit may receive the electrical signal and output the phase modulated signal.

[0095] The electrical signal obtained by the balanced detection of the first detector PD1 and the second detector PD2 can be expressed as: Wherein θ(t) is the phase information outputted after the frequency discriminator is integrated; after the integration circuit integrates the electrical signal, it outputs the phase modulation signal Kθ(t).

[0096] For example, Figure 2As shown, the signal generating 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 generating circuit 122 integrates the electrical signal to obtain the phase modulated signal; in addition, in some embodiments, the signal generating circuit 122 can also amplify the integration result of the signal generating circuit 122 to obtain the phase modulated signal.

[0097] It should be noted that in some other embodiments of the present invention, the signal generating circuit may include an integrating circuit that receives the electrical signal and outputs the phase-modulated signal. The integrating circuit may also amplify the electrical signal, integrating and amplifying the received electrical signal before outputting it.

[0098] In some other embodiments, the signal generating circuit may further include: a gain circuit, which may perform a gain on the integration result of the integration circuit to obtain the phase modulated signal.

[0099] For example, Figure 5 As shown, the signal generating circuit 122 includes an integration circuit 1221 and a gain circuit 1223. The integration circuit 1221 receives the electrical signal obtained by balanced detection by the first detector PD1 and the second detector PD2 and integrates the electrical signal. The gain circuit 1223 is connected to the integration circuit 1221 and amplifies the integration result of the integration circuit 1221 to obtain the phase-modulated signal. The first modulator can modulate the transmitted optical signal according to the phase-modulated signal and output it.

[0100] 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 the frequency jitter, thereby eliminating the frequency jitter of the transmitted optical signal and stabilizing the frequency of the optical signal modulated by the first modulator at the center frequency, thereby reducing the frequency jitter of the output light and compressing the output light width.

[0101] In some embodiments, the first modulator may receive the initial light or the initial frequency-modulated light, modulate the initial light or the initial frequency-modulated light based on the phase modulation signal, and then output the modulated light. The linewidth compression circuit may further include a first optical splitter, wherein an input end of the first optical splitter may be connected to the first modulator, a first output end of the first optical splitter may output the first optical signal, and a second output end of the first optical splitter may output output light. For example, the output light may be emitted into the external space for obstacle detection.

[0102] The input end of the first modulator can receive the initial light or the initial frequency-modulated light; the output end of the first modulator can be connected to the input end of the first optical splitter, and the first optical splitter can split the light modulated by the first modulator into the outgoing light and the first optical signal. The outgoing light is modulated by the first modulator, and the light field of the outgoing light can be expressed as:

[0103]

[0104] 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.

[0105] For example, Figure 2 As shown, the first modulator 123 is a phase modulator. The input end of the first modulator 123 is connected to the laser 110 to receive the initial light; the output end of the first modulator 123 is connected to the input end of the first optical splitter 124 to provide modulated light to the first optical splitter 124; the first optical splitter 124 splits the light modulated by the first modulator 123 into a first optical signal and an outgoing light.

[0106] The outgoing light is light modulated by the first modulator 123 . The frequency jitter of the outgoing light is eliminated during the modulation process of the first modulator 123 . The line width of the outgoing light is compressed during the modulation process, and the line width of the outgoing light is smaller.

[0107] In some embodiments, the first optical splitter has a large splitting ratio; the ratio of the energy of the outgoing light split by the first optical splitter to the energy of the first optical signal split is N, where N is greater than 1, so as to maximize the outgoing light energy. For example, Figure 2 As shown, the splitting ratio of the first optical splitter 124 is greater than or equal to 9:1; the ratio of the energy of the outgoing light split by the first optical splitter 124 to the energy of the split first optical signal is greater than or equal to 9.

[0108] It should be noted that the first optical splitter may be located in an optical path downstream of the first modulator, and may receive light modulated by the first modulator. The first optical signal may be initial frequency-modulated light formed by modulating part of the initial light.

[0109] refer to Figure 6 , showing a schematic structural diagram of the fourth embodiment of the frequency modulated light source disclosed in the present invention

[0110] It should be noted that Figure 6 The structures of the laser and the photoelectric conversion circuit and the like in some of the illustrated embodiments may be the same as those of the laser and the photoelectric conversion circuit and the like in the aforementioned embodiments.

[0111] In some embodiments of the present disclosure, the second modulator is not provided in the frequency discriminator, and the frequency of the operating point of the frequency discriminator is a fixed value and is not adjustable.

[0112] In some embodiments, the signal generating circuit may output a phase modulated signal based on the electrical signal converted by the conversion circuit and a reference signal generated by the frequency modulation circuit.

[0113] The signal generating circuit can subtract the reference signal during the process of integrating and gaining the electrical signal converted by the conversion circuit, thereby also eliminating the influence of frequency modulation on line width compression.

[0114] For example, Figure 6 As shown, the frequency modulation circuit 230 is connected to the signal generating circuit 222 of the linewidth compression circuit 220 and provides a reference signal to the signal generating circuit 222. After the signal generating circuit 222 integrates and amplifies the electrical signal obtained by the balanced detection conversion of the first detector PD1 and the second detector PD2 of the photoelectric conversion circuit 2212 in the conversion circuit 221, the signal generating circuit 222 subtracts the reference signal from the amplified result to generate the phase modulation signal, which is provided to the first modulator 223.

[0115] Furthermore, since the discriminator lacks a second modulator, the operating frequency of the discriminator 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 discriminator, similarly suppressing low-frequency disturbances.

[0116] For example, 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, and provides 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.

[0117] refer to Figure 7 , shows a structural schematic diagram of the fourth embodiment of the frequency-modulated light source disclosed in the present invention.

[0118] It should be noted that Figure 7 The structures of the laser and the photoelectric conversion circuit and the like in some of the illustrated embodiments may be the same as those of the laser and the photoelectric conversion circuit and the like in the aforementioned embodiments.

[0119] In some embodiments of the present disclosure, the frequency-modulated light source may further include a second spectrometer, the input end of the second spectrometer may receive the initial light or the initial frequency-modulated light, the first output end of the second spectrometer may output the first optical signal, and the second output end of the second spectrometer may output a third optical signal; the input end of the first modulator may be connected to the second output end of the second spectrometer, and the first modulator may modulate the third optical signal based on the phase modulation signal and output output light.

[0120] After the second optical splitter can split the initial light or the 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 output light.

[0121] For example, Figure 7 As shown, the input end of the second optical splitter 325 is connected to the light source 310 to receive the initial light. The second optical splitter 325 splits the initial light into a first optical signal and a third optical signal, which are provided to the first output end and the second output end respectively. The first optical signal and the third optical signal are respectively parts of the initial light.

[0122] In some embodiments, the second optical splitter has a large splitting ratio; the ratio of the energy of the outgoing light split by the second optical splitter to the energy of the first optical signal split is N, where N is greater than 1, so as to maximize the outgoing light energy. For example, Figure 7 As shown, the splitting ratio of the second optical 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.

[0123] Continue to refer Figure 7 The first output end of the second optical splitter 325 is connected to the discriminator 3211 of the conversion circuit 321 in the linewidth compression circuit 320. The discriminator 3211 receives the first optical signal provided to the first output end 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, wherein the first detector PD1 and the second detector PD2 output an electrical signal reflecting the light intensity information of the second optical signal through balanced detection; the integration circuit 3221 and the gain circuit 3223 of the signal generating circuit 322 respectively perform integration and gain on the electrical signal output by the photoelectric conversion circuit 3212 to form the phase modulated signal.

[0124] In some embodiments of the present disclosure, the frequency modulated light source may further include: a delay device, the input end of the delay device may be connected to the second output end of the second optical splitter, and the output end of the delay device may be connected to the input end of the first modulator.

[0125] The delay device 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 device can extend the optical path of the third optical signal to match the time difference between the generated phase modulation signal and the third optical signal, so that the third optical signal can be modulated before being emitted.

[0126] For example, Figure 7 As shown, the delay device 350 is connected to the optical path between the second optical splitter 325 and the first modulator 323. In a specific implementation, the delay device 350 can be a delay optical fiber.

[0127] 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 of the aforementioned embodiment.

[0128] In some other embodiments, the center frequency feedback circuit 340 may be the same as or similar to the center frequency feedback circuit 340 in the aforementioned embodiment.

[0129] refer to Figure 8 , shows a structural schematic diagram of the fifth embodiment of the frequency-modulated light source disclosed in the present invention.

[0130] It should be noted that Figure 8 The structures of the laser and the photoelectric conversion circuit and the like in some of the illustrated embodiments may be the same as those of the laser and the photoelectric conversion circuit and the like in the aforementioned embodiments.

[0131] In some embodiments of the present disclosure, the initial light is fixed-frequency light, and the first modulator may include: an IQ modulator; the signal generating circuit may include an electrical signal coupler, and the electrical signal coupler may output the phase-modulated signal; the IQ modulator may modulate the transmitted optical signal according to the phase-modulated signal to output frequency-modulated light.

[0132] An IQ modulator is a device with phase modulation characteristics. It consists of two sub-Mach-Zehnder interferometers and one mother Mach-Zehnder interferometer, and phase modulation can be achieved by adjusting three voltages.

[0133] Furthermore, the center frequency before entering the IQ modulator is at k = 0, and changes to k = -1 after exiting the IQ modulator. The IQ modulator cooperates with an electrical signal coupler to couple the electrical signal generated by the balanced detection result with the reference signal. In a specific implementation, the electrical signal coupler can have an ideal phase integration effect, and the signal generation circuit including the electrical signal coupler performs integration via the electrical signal coupler.

[0134] For example, Figure 8 As shown, the signal generating circuit 422 is connected to the first detector PD1 and the second detector PD2 to receive the electrical signal generated by the balance detection result. The signal generating circuit 422 is also connected to the frequency modulation circuit 430 to receive the reference signal. The electrical signal coupler 4222 of the signal generating circuit 422 couples the electrical signal generated by the balance detection result and the reference signal. The signal generating circuit 422 is also connected to the first modulator 423 to provide the coupling result to the first modulator 423.

[0135] In some specific implementations, the electrical signal coupler 4222 includes a voltage controlled oscillator (VCO). The signal generating 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.

[0136] In addition, the frequency modulation circuit 430 is also connected to the second modulator 4213 and provides 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.

[0137] The initial light is fixed-frequency light. The optical signal transmitted by the first modulator 4213 is fixed-frequency light. The reference signal generated by the frequency modulation circuit 430 is coupled with the electrical signal generated by the balance detection result via the electrical signal coupler 4222, thereby frequency modulating the fixed-frequency light and achieving linewidth compression, thereby outputting frequency-modulated light with a narrow linewidth.

[0138] In some embodiments, the electrical signal generated by the balanced detection result coupled with the reference signal is a gain-added electrical signal. The electrical signal generated by the balanced detection result is amplified and then coupled with the reference signal.

[0139] It should be noted that the input end 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, Figure 8As shown, the signal decomposer 423 a is a 90° bridge connected between the signal generating circuit 422 and the first modulator 423 .

[0140] It should also be noted that the input end 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 of the aforementioned embodiment.

[0141] refer to Figure 9 , shows a structural schematic diagram of the sixth embodiment of the frequency-modulated light source disclosed in the present invention.

[0142] It should be noted that Figure 9 The structures of the laser and the photoelectric conversion circuit and the like in some of the illustrated embodiments may be the same as those of the laser and the photoelectric conversion circuit and the like in the aforementioned embodiments.

[0143] In some embodiments of the present disclosure, setting the first modulator as an IQ modulator is also applicable to a feedforward scheme.

[0144] In some embodiments of the present disclosure, the second optical splitter can split the received initial light or initial frequency-modulated light into a first optical signal and a third optical signal, and 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 and then output it.

[0145] like Figure 9 As shown, the first modulator 523 connected to the optical path downstream of the delay device 550 is configured as an IQ modulator. The signal generating circuit 422 connected to the frequency modulation circuit 530 is connected between the photoelectric conversion circuit 5212 and the first modulator 523 .

[0146] And if Figure 9 As shown, in the feedforward scheme, the signal generation circuit 522 can amplify and couple the reference signal and the electrical signal generated by the balanced detection result. The generated phase modulator signal not only eliminates phase noise but also frequency modulates 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.

[0147] In some embodiments, the frequency modulated light source further includes a signal splitter. The signal splitter 523a can be the same as or similar to the signal splitter 423a. For example, the signal splitter 523a is a 90° bridge connected between the signal generating circuit 522 and the first modulator 523.

[0148] refer to Figure 10, shows a structural schematic diagram of the seventh embodiment of the frequency-modulated light source disclosed in the present invention.

[0149] It should be noted that Figure 10 The structures of the laser and the photoelectric conversion circuit and the like in some of the illustrated embodiments may be the same as those of the laser and the photoelectric conversion circuit and the like in the aforementioned embodiments.

[0150] In some embodiments of the present disclosure, the frequency-modulated light source may include: multiple lasers, and the multiple lasers may generate multiple initial lights in a time-sharing manner; the difference in central wavelengths of the initial lights generated by different lasers may be an integer multiple of a demodulation period, where the demodulation period is the period during which the amplitude of the second optical signal changes with the frequency of the first optical signal.

[0151] Multiple lasers can share a single 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 over which the amplitude of the second optical signal varies with the frequency of the first optical signal being the discriminator period. By ensuring that the difference in the center wavelengths of light generated by different lasers is an integer multiple of the discriminator period, the light generated by all lasers can be matched to the frequency of the discriminator's operating point.

[0152] For example, Figure 10 As shown, the input end of the first modulator 623 is connected to the output ends of the plurality of lasers 610 to receive the initial light generated by all the lasers 610. The plurality of lasers 610 are connected to the frequency modulation circuit 630, and each of the lasers 610 generates initial light of a different wavelength under the control of a reference signal.

[0153] Figure 10 The frequency-modulated light source shown uses a feedback scheme. The first optical splitter 624 splits the light modulated by the first modulator 623 into 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 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. After integration by the integration circuit 6221 of the signal generation circuit 622, the resulting phase-modulated signal is provided to the first modulator 623. The first modulator 623 further modulates subsequent light.

[0154] 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 may also generate multiple initial lights of different wavelengths in a time-sharing manner; the lasers generate multiple initial lights of different wavelengths in a time-sharing manner, and the difference in the center wavelengths of the initial lights of different wavelengths is an integer multiple of the frequency discrimination period, where the frequency discrimination period is the period over which the amplitude of the second optical signal varies with the frequency of the first optical signal.

[0155] It should also be noted that Figure 10 The frequency-modulated light source shown uses a feedback scheme. In other embodiments of the present invention, a frequency-modulated light source that generates multiple initial lights of different wavelengths may also use a feedforward scheme, namely, a second optical splitter is used to split the received light into a first optical signal and a third optical signal; a conversion circuit and a signal generation circuit are used to convert the first signal light to generate a phase-modulated signal; and a first modulator is used to modulate the third optical signal for output.

[0156] In addition, in other embodiments of the present invention, the frequency modulated light source may further include an electro-optical modulator to modulate the fixed-frequency light generated by the laser to obtain frequency modulated light. In some embodiments, the electro-optical modulator may include a phase modulator, an IQ modulator, a semiconductor optical amplifier, or an acousto-optic modulator.

[0157] For example, Figure 11 The frequency-modulated light source includes a laser assembly 701, which includes a laser 710 and an electro-optical modulator 711. The electro-optical modulator 711 is located in the optical path downstream of the laser 710. The laser 710 can generate fixed-frequency light; the electro-optical modulator 711 receives the fixed-frequency light generated by the laser 710 and modulates the fixed-frequency light to obtain frequency-modulated light.

[0158] The linewidth compression circuit 720 is located in the optical path downstream of the laser assembly 701. Specifically, the input of the linewidth compression circuit 720 is connected to the output of the electro-optical 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 on a silicon photonic chip to improve integration.

[0159] In some other embodiments of the present invention, the frequency-modulated light source may further include an optical phase-locked loop (PLL). This optical phase-locked loop (PLL) is connected to the 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, further compressing the linewidth of the frequency-modulated light source and improving frequency modulation linearity.

[0160] Correspondingly, the present invention also provides a transmitting assembly.

[0161] The transmitting component includes: a frequency-modulated light source, which includes: 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, which includes 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 light intensity information of a second optical signal; the linewidth compression circuit is also 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 also configured to modulate the transmitted optical signal based on the phase-modulated signal and output it to form an output light.

[0162] In some embodiments of the present disclosure, the frequency-modulated light source is the frequency-modulated light source of the present invention. The specific technical solutions for the frequency-modulated light source are described in the aforementioned embodiments of the frequency-modulated light source. The present invention will not be further elaborated here. The linewidth compression circuit modulates the transmitted optical signal based on a phase modulation signal, resulting in a larger feedback loop bandwidth. The frequency-modulated light source produces a narrower linewidth of light and higher frequency modulation linearity, resulting in improved performance of the resulting transmitting assembly.

[0163] In some embodiments of the present disclosure, the transmitting assembly further includes: at least one lens, the at least one lens being located in an optical path downstream of the outgoing light, and the at least one lens being configured to shape the outgoing light.

[0164] In addition, the present disclosure also provides a laser radar.

[0165] The laser radar includes: a transmitting component, which includes: a frequency-modulated light source, which includes: 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, which includes at least part 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 light intensity information of a second optical signal; the linewidth compression circuit is also 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 also configured to modulate the transmitted optical signal based on the phase-modulated signal and output it to form an outgoing light; the outgoing light forms an echo light after being reflected by an object; and a receiving component, which is configured to receive the echo light.

[0166] In some embodiments of the present disclosure, the transmitting assembly is the transmitting assembly of the present invention. The specific technical solution of the transmitting assembly is referred to the embodiment of the transmitting assembly described above. The present invention will not be repeated here.

[0167] In some embodiments of the present disclosure, the laser radar is a frequency-modulated continuous-wave laser radar. After receiving the echo light, the laser radar couples the echo light with the local oscillator light separated from the outgoing light to form coherent light for detection. The frequency-modulated light source in the transmitting assembly produces light with a narrower linewidth and higher frequency modulation linearity, enabling higher-precision, faster-speed, and longer-range laser detection.

[0168] In summary, 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, thereby generating a phase-modulated signal. The linewidth compression circuit also modulates the transmitted optical signal according to the phase-modulated signal and outputs it. This modulates the transmitted optical signal according to the phase-modulated signal and outputs it, resulting in a wider feedback loop bandwidth and significantly improving the performance of the frequency-modulated light source.

[0169] It should be understood that the division of the modules and units in the above system is only a division of logical functions. In actual implementation, there may be other division methods. In actual implementation, they may be fully or partially integrated into a physical entity, or they may be physically separated. In addition, the modules and units in the device can be implemented in the form of a processor calling software; for example, the device includes a processor, the processor is connected to a memory, and the memory stores instructions. The processor calls the instructions stored in the memory to implement any of the above methods or realize the functions of the modules and units of the device. The processor is, for example, a general-purpose processor, such as a central processing unit (CPU) or a microprocessor, and the memory is a memory within the system or a memory outside the system. Alternatively, the modules and units in the device can be implemented in the form of hardware circuits, and the functions of some or all modules can be realized by designing the hardware circuits. The hardware circuit 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 functions of some or all of the above modules are realized by designing the logical relationship between the components in the circuit. For another example, in another implementation, the hardware circuit can be implemented by a programmable logic device (PLD), which can include a large number of logic gate circuits. The logical relationship between the logic gate circuits is configured through a configuration file, thereby realizing the functions of some or all of the above modules. All modules of the above system can be implemented in the form of a processor calling a program, or in the form of a hardware circuit, or in part by a processor calling a program, and the rest by a hardware circuit.

[0170] Although the present disclosure is disclosed as above, the present disclosure is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present disclosure. Therefore, the scope of protection of the present disclosure should be based on the scope defined by the claims.

Claims

1. A frequency modulated light source, characterized in that: include: Lasers and linewidth compression circuits; The laser is configured to generate initial light; The linewidth compression circuit is configured to receive a first optical signal, which includes at least a portion of the initial light or an 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 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; and the linewidth compression circuit is further configured to modulate the transmitted optical signal based on the phase modulation signal and output it.

2. The frequency modulated light source according to claim 1, wherein The linewidth compression circuit includes: a conversion circuit, a signal generating 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 end of the signal generating circuit is connected to the output end of the conversion circuit, and is configured to receive the electrical signal and output the phase modulated signal; The first modulator is configured to modulate the transmitted optical signal according to the phase modulation signal and then output the modulated optical signal.

3. The frequency modulated light source according to claim 2, wherein: 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.

4. The frequency modulated light source according to claim 3, wherein: The frequency discriminator includes at least one of a Mach-Zehnder interferometer, a fiber Bragg grating, a bandpass filter, and a microring.

5. The frequency modulated light source according to claim 3, wherein: 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.

6. The frequency modulated light source according to claim 3, wherein: 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 generating circuit generates a phase modulation signal according to the first electrical signal and the second electrical signal.

7. The frequency modulated light source according to claim 6, wherein: The photoelectric conversion circuit is further configured to separate 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 according to the third electrical signal and provide the center frequency feedback signal to the laser or the second modulator in the conversion circuit.

8. The frequency modulated light source according to claim 2, wherein: 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 and then output the modulated light; The linewidth compression circuit further includes a first optical splitter, wherein an input end of the first optical splitter is connected to the first modulator, a first output end of the first optical splitter outputs the first optical signal, and a second output end of the first optical splitter outputs outgoing light.

9. The frequency modulated light source according to claim 2, wherein: The frequency-modulated light source also includes a second spectrometer, an input end of the second spectrometer receives the initial light or the initial frequency-modulated light, a first output end of the second spectrometer outputs the first optical signal, and a second output end of the second spectrometer outputs a third optical signal; an input end of the first modulator is connected to the second output end of the second spectrometer, and the first modulator is configured to modulate the third optical signal based on the phase modulation signal and output output light.

10. The frequency modulated light source according to claim 9, wherein: The frequency modulated light source further includes a delay device, wherein the input end of the delay device is connected to the second output end of the second optical splitter, and the output end of the delay device is connected to the input end of the first modulator.

11. The frequency modulated light source according to claim 2, wherein: The first modulator includes at least one of a phase modulator, an IQ modulator, a semiconductor optical amplifier, and an acousto-optic modulator.

12. The frequency modulated light source according to claim 2, wherein: When the initial light is frequency modulated light, or the linewidth compression circuit receives initial frequency modulated light, the signal generating circuit includes: an integrating circuit configured to receive the electrical signal and output the phase modulated signal.

13. The frequency modulated light source according to claim 2, wherein: The initial light is a fixed-frequency light, and the first modulator includes: an IQ modulator; the signal generating circuit includes an electrical signal coupler, and the electrical signal coupler is configured to output the phase modulated signal; The IQ modulator modulates the transmitted optical signal according to the phase modulation signal and outputs frequency modulated light.

14. The frequency modulated light source according to claim 13, wherein: The electrical signal coupler includes a voltage-controlled oscillator.

15. The frequency modulated light source according to claim 1, wherein: The frequency modulated light source comprises: a plurality of lasers, wherein the plurality of lasers generate a plurality of initial lights in a time-sharing manner; The difference in central wavelengths of initial light generated by different lasers is an integer multiple of a frequency discrimination period, where the frequency discrimination period is a period during which the amplitude of the second optical signal changes with the frequency of the first optical signal.

16. The frequency modulated light source according to claim 1, wherein: The laser generates multiple initial lights of different wavelengths in a time-sharing manner, and the difference in central wavelengths of the initial lights of different wavelengths is an integer multiple of a demodulation period, where the demodulation period is a period during which the amplitude of the second optical signal changes with the frequency of the first optical signal.

17. A launching assembly, characterized in that: include: A frequency modulated light source, comprising: a laser and a linewidth compression circuit; the laser being configured to generate initial light; the linewidth compression circuit being configured to receive a first optical signal, the first optical signal comprising at least a portion of the initial light or initial frequency-modulated light formed by modulating the initial light; the linewidth compression circuit being further configured to transmit the first optical signal and convert the frequency information of the first optical signal into light intensity information of a second optical signal; the linewidth compression circuit being further configured to obtain the frequency noise of the initial light based on the second optical signal to generate a phase modulation signal; and the linewidth compression circuit being further configured to modulate the transmitted optical signal based on the phase modulation signal and output the modulated signal to form output light.

18. The launch assembly according to claim 17, wherein: Also includes: At least one lens is located in a light path downstream of the outgoing light, and the at least one lens is configured to shape the outgoing light.

19. A laser radar, characterized in that: include: A transmitting assembly, comprising: a frequency-modulated light source, the frequency-modulated light source comprising: a laser and a linewidth compression circuit; the laser being configured to generate initial light; the linewidth compression circuit being configured to receive a first optical signal, the first optical signal comprising at least a portion of the initial light or initial frequency-modulated light formed by modulating the initial light; the linewidth compression circuit being further configured to transmit the first optical signal and convert the frequency information of the first optical signal into light intensity information of a second optical signal; the linewidth compression circuit being further configured to obtain frequency noise of the initial light based on the second optical signal to generate a phase-modulated signal; and the linewidth compression circuit being further configured to modulate the transmitted optical signal based on the phase-modulated signal and output the modulated signal to form output light. The outgoing light forms echo light after being reflected by the object; A receiving component is configured to receive the echo light.

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