Signal generating device and method

Abstract

The application provides a signal generation device and method, comprising: at least two local oscillation lasers for generating at least two laser signals with different frequencies; an oscillation loop for oscillating based on the at least two laser signals with different frequencies to generate a first radio frequency signal corresponding to each frequency of the laser signals; a feedback controller corresponding to each of the local oscillation lasers for generating a feedback signal based on the first radio frequency signal corresponding to each frequency of the laser signals, and inputting the feedback signal into the corresponding local oscillation laser to adjust the frequency of the laser signal output by the local oscillation laser; wherein after the frequencies of the at least two laser signals generated by the at least two local oscillation lasers are locked to different resonance peaks of an optical filter in the oscillation loop, the optical filter is further used for outputting a first optical carrier terahertz signal, and the frequency of the first optical carrier terahertz signal is an integer multiple of the free spectral range of the optical filter.

Description

Technical Field

[0001] This invention relates to the field of signal generation technology, and more specifically to a signal generation device and method. Background Technology

[0002] High-quality microwave signals have wide applications in communications, radar, and measurement. Phase noise in microwave signals often affects system performance in various scenarios. In wireless communication systems, excessive phase noise in the microwave signal used as the transmit carrier can lead to crosstalk between adjacent channels, thus affecting communication quality. In radar systems, microwave signal phase noise directly impacts radar resolution and detection range. With the increasing demand for high-bit-rate wireless services, ultra-high-definition video, and data downloads, higher-speed information transmission is an inevitable trend. To meet future communication bandwidth requirements, it is necessary to explore higher frequency resources. The terahertz band possesses enormous bandwidth, enabling ultra-high wireless communication rates even with relatively low spectral efficiency. Therefore, the generation of high-quality terahertz and microwave signals is crucial for improving system performance. Summary of the Invention

[0003] In view of the above problems, the present invention provides a signal generation device and method.

[0004] According to a first aspect of the present invention, a signal generating apparatus is provided, comprising: at least two local oscillator lasers for generating at least two laser signals of different frequencies; an oscillation loop for oscillating based on the at least two laser signals of different frequencies to generate a first radio frequency signal corresponding to each laser signal of frequency; and a feedback controller, corresponding one-to-one with the local oscillator lasers, for generating a feedback signal based on the first radio frequency signal corresponding to each laser signal of frequency, and inputting the feedback signal to the corresponding local oscillator laser to adjust the frequency of the laser signal output by the local oscillator laser; wherein, after the frequencies of the at least two laser signals generated by the at least two local oscillator lasers are locked to different resonant peaks corresponding to the optical filter in the oscillation loop, the optical filter is further configured to output a first optical terahertz signal, the frequency of which is an integer multiple of the free spectrum range of the optical filter.

[0005] According to an embodiment of the present invention, the device further includes: a first optical coupler, the input end of which is connected to the output ends of at least two local oscillator lasers, for outputting a second optical terahertz signal after the frequencies of at least two laser signals generated by the at least two local oscillator lasers are locked to different resonant peaks corresponding to the optical filter, wherein the frequency of the second optical terahertz signal is continuously adjustable.

[0006] According to an embodiment of the present invention, the device further includes: an optoelectronic frequency divider, disposed at the output end of the optical filter or the output end of the first optical coupler, for performing optoelectronic conversion and frequency division on the first optical terahertz signal to obtain a first microwave signal, or for performing frequency division on the second optical terahertz signal to obtain a second microwave signal.

[0007] According to an embodiment of the present invention, the oscillation loop includes: an optical phase modulator, corresponding one-to-one with a local oscillator laser, for modulating the laser signal output by the corresponding local oscillator laser to obtain multiple modulated optical signals; a second optical coupler, for combining the multiple modulator optical signals into one channel to obtain a combined signal; an optical filter, for performing concave filtering on the combined signal to obtain a concave-filtered optical signal; a first photodetector, for performing beat frequency analysis on the concave-filtered optical signal to obtain a second radio frequency signal; a first radio frequency power divider, for splitting the second radio frequency signal into at least two channels of second radio frequency signals with equal power; and a first radio frequency filter, corresponding one-to-one with a local oscillator laser, each first radio frequency filter being used to process one channel of second radio frequency signal. A first RF amplifier, corresponding to a first RF filter, amplifies the third RF signal output from the corresponding first RF filter to obtain the first RF signal. The frequency of the first RF signal is determined by the frequency of the corresponding local oscillator laser and the resonant peak angular frequency of the optical filter. A second RF power divider, corresponding to a first RF amplifier, splits the first RF signal into two equal-power first RF signals, inputting one of the first RF signals into the corresponding optical phase modulator. A feedback controller generates a feedback signal based on the other first RF signal and inputs the feedback signal into the corresponding local oscillator laser to adjust the frequency of the laser signal output by the local oscillator laser.

[0008] According to an embodiment of the present invention, the oscillation loop includes: an optical phase modulator, corresponding one-to-one with a local oscillator laser, used to modulate the laser signal output by the corresponding local oscillator laser to obtain multiple modulated optical signals; a polarization adjuster, used to be disposed at the output end of some optical phase modulators to adjust the polarization state of the modulated optical signal output by the corresponding optical phase modulator, so that the polarization state of the modulated optical signal after polarization state adjustment is orthogonal to the polarization state of the modulated optical signal after polarization state adjustment; a polarization combiner, used to combine the modulated optical signal after polarization state adjustment and the modulated optical signal after polarization state adjustment into one path to obtain a combined signal; an optical filter, used to perform concave filtering on the combined signal to obtain a concave-filtered optical signal; a polarization beam splitter, used to split the concave-filtered optical signal into at least two concave-filtered optical signals; and a first optical... Each photodetector corresponds to a local oscillator laser. Each first photodetector is used to beat the filtered optical signal to obtain a second radio frequency (RF) signal. A first radio frequency amplifier corresponds to a first radio frequency (RF) filter and amplifies the third RF signal output by the corresponding first RF filter to obtain a first RF signal. The frequency of the first RF signal is determined by the frequency of the corresponding local oscillator laser and the resonant peak angular frequency of the optical filter. A second RF power divider corresponds to a first RF amplifier and splits the first RF signal into two equal-power first RF signals, inputting one of these signals to the corresponding optical phase modulator. A feedback controller generates a feedback signal based on the other first RF signal and inputs the feedback signal to the corresponding local oscillator laser to adjust the frequency of the laser signal output by the local oscillator laser.

[0009] According to an embodiment of the present invention, the oscillation loop includes: an optical phase modulator, corresponding one-to-one with a local oscillator laser, used to modulate the laser signal output by the corresponding local oscillator laser to obtain multiple modulated optical signals; a first optical wavelength division multiplexer, used to combine the multiple modulated optical signals into one path to obtain a combined signal; an optical filter, used to perform concave filtering on the combined signal to obtain a concave-filtered optical signal; a second optical wavelength division multiplexer, used to split the concave-filtered optical signal into at least two concave-filtered optical signals; and a first photodetector, corresponding one-to-one with a local oscillator laser, each first photodetector being used to beat one concave-filtered optical signal to obtain a second radio frequency signal; the second... A radio frequency amplifier, corresponding one-to-one with the first radio frequency filter, is used to amplify the third radio frequency signal output by the corresponding first radio frequency filter to obtain the first radio frequency signal; the frequency of the first radio frequency signal is determined by the frequency of the corresponding local oscillator laser and the resonant peak angular frequency of the optical filter; a second radio frequency power divider, corresponding one-to-one with the first radio frequency amplifier, is used to split the first radio frequency signal into two first radio frequency signals with equal power, and input one of the first radio frequency signals into the corresponding optical phase modulator; wherein, a feedback controller is used to generate a feedback signal based on the other first radio frequency signal, and input the feedback signal into the corresponding local oscillator laser to adjust the frequency of the laser signal output by the local oscillator laser.

[0010] According to an embodiment of the present invention, the oscillation loop includes: a third optical coupler for merging at least two laser signals with different frequencies into a single laser signal; an optical phase modulator for modulating the single laser signal to obtain a modulated optical signal; an optical filter for performing concave filtering on the modulated optical signal to obtain a concave-filtered optical signal; a first photodetector for performing beat frequency analysis on the concave-filtered optical signal to obtain a second radio frequency signal; a first radio frequency power divider for splitting the second radio frequency signal into at least two equal-power paths; a first radio frequency filter, corresponding one-to-one with the local oscillator laser, each first radio frequency filter filtering one path of the second radio frequency signal to obtain a third radio frequency signal; and a first radio frequency amplifier, connected to the first radio frequency filter... Each of the following components corresponds to a first RF amplifier: a second RF power divider, which amplifies the third RF signal output from the corresponding first RF filter to obtain a first RF signal; the frequency of the first RF signal is determined by the frequency of the corresponding local oscillator laser and the resonant peak angular frequency of the optical filter; a second RF power divider, which corresponds to the first RF amplifier, is used to split the first RF signal into two first RF signals with equal power; an RF combiner is used to combine the first RF signals output from each of the second RF power dividers into a fourth RF signal, and input the second RF signal into the optical phase modulator; and a feedback controller is used to generate a feedback signal based on the other first RF signal, and input the feedback signal into the corresponding local oscillator laser to adjust the frequency of the laser signal output by the local oscillator laser.

[0011] According to an embodiment of the present invention, the device further includes: a fourth optical coupler disposed at the output end of the optical filter, used to split the first optical terahertz signal to obtain two first optical terahertz signals; and a second photodetector disposed at the output end of the fourth optical coupler or the output end of the first coupler, used to beat the first optical terahertz signal to obtain a first terahertz signal, or to beat the second optical terahertz signal to obtain a second terahertz signal.

[0012] According to an embodiment of the present invention, the feedback controller generates a feedback signal based on a first radio frequency signal corresponding to a laser signal of each frequency, including: mixing a radio frequency reference signal with the first radio frequency signal, extracting the change in the center angular frequency of the local oscillator laser relative to the center angular frequency of the optical filter, obtaining an error signal, and generating a feedback signal based on the error signal.

[0013] According to a second aspect of the present invention, a signal generation method is provided, which is implemented based on the above-described signal generation apparatus. The method includes: generating at least two laser signals of different frequencies using at least two local oscillator lasers; oscillating based on the at least two laser signals of different frequencies using an oscillation loop to generate a first radio frequency signal corresponding to each laser signal of a given frequency; generating a feedback signal based on the first radio frequency signal corresponding to each laser signal of a given frequency using a feedback controller; and inputting the feedback signal to the corresponding local oscillator laser to adjust the frequency of the laser signal output by the local oscillator laser; wherein the feedback controller corresponds one-to-one with the local oscillator laser; and after the frequencies of the at least two laser signals generated by the at least two local oscillator lasers are locked to different resonant peaks corresponding to the optical filters in the oscillation loop, a terahertz signal or a microwave signal is output.

[0014] The signal generation apparatus and method provided by this invention have at least the following technical effects:

[0015] This device and method can lock at least two different local oscillator lasers to different resonant peaks of the same optical filter, outputting a terahertz signal with high frequency stability. The frequency of the terahertz signal can be changed by adjusting the frequency of the local oscillator laser, and the frequency is limited only by the adjustment range of the local oscillator laser frequency and the bandwidth of the photodetector. The frequency of the generated optical terahertz signal is limited only by the frequency adjustment range of the laser. The frequency stability of the generated terahertz signal is limited by the relative fluctuations between different resonant frequencies of the optical filter.

[0016] This device and method can achieve two ways of outputting optical terahertz signals. One way is to directly output from the bandpass filter output port of the optical filter, and the frequency of the first optical terahertz signal is an integer multiple of the free spectrum range of the optical filter. The other way is to combine the locked two local oscillator lasers through an optical coupler, and the resulting second terahertz signal can be continuously adjusted in frequency.

[0017] Since at least two different local oscillator lasers are locked to different resonant peaks of a unified optical filter, and a portion of the optical path is shared, the beat-frequency terahertz signal can remove some common-mode noise, resulting in a terahertz signal with phase noise lower than that of a single-channel locked local oscillator laser.

[0018] The device and method can also be combined with frequency division to generate microwave signals with lower phase noise. After the optical terahertz signal is frequency divided, the phase noise of the generated microwave signal is reduced. Attached Figure Description

[0019] The above-described features, other objects, and advantages of the present invention will become clearer from the following description of embodiments of the invention with reference to the accompanying drawings, in which:

[0020] Figure 1 A schematic diagram of a signal generating apparatus according to a first embodiment of the present invention is shown.

[0021] Figure 2 A schematic diagram of a signal generating apparatus according to a second embodiment of the present invention is shown.

[0022] Figure 3 A schematic diagram of a signal generating apparatus according to a third embodiment of the present invention is shown.

[0023] Figure 4 The schematic diagram illustrates the spectral diagram and radio frequency spectrum diagram corresponding to each signal during the signal generation process according to an embodiment of the present invention;

[0024] Figure 5 A schematic diagram of a signal generating apparatus according to a fifth embodiment of the present invention is shown.

[0025] Figure 6 A schematic diagram of a signal generating apparatus according to a sixth embodiment of the present invention is shown.

[0026] Figure 7 A schematic diagram of a signal generating apparatus according to a seventh embodiment of the present invention is shown.

[0027] Figure 8 A flowchart illustrating a signal generation method according to an embodiment of the present invention is shown schematically;

[0028] Figure 9 A phase noise diagram according to an embodiment of the present invention is illustrated schematically;

[0029] Figure 10 The diagram illustrates the phase noise measurement results when the beat frequency signal frequency interval is 10 GHz and 20 GHz according to an embodiment of the present invention. Detailed Implementation

[0030] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the invention. In the following detailed description, numerous specific details are set forth to provide a thorough understanding of the embodiments of the invention for ease of explanation. However, it will be apparent that one or more embodiments may be practiced without these specific details. Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concept of the invention.

[0031] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention. The terms “comprising,” “including,” etc., as used herein indicate the presence of the stated features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.

[0032] All terms used herein (including technical and scientific terms) have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein are to be interpreted in a manner consistent with the context of this specification, and not in an idealized or overly rigid way.

[0033] When using expressions such as "at least one of A, B and C", they should generally be interpreted in accordance with the meaning that is commonly understood by those skilled in the art (e.g., "a system having at least one of A, B and C" should include, but is not limited to, a system having A alone, a system having B alone, a system having C alone, a system having A and B, a system having A and C, a system having B and C, and / or a system having A, B and C, etc.).

[0034] In developing this invention, the applicant discovered that traditional microwave signal generation methods typically involve direct generation via an oscillator. However, the phase noise of the generated microwave signal is limited by the quality factor of the resonator. The quality factor of traditional microwave resonators decreases rapidly with increasing resonant frequency, making it difficult to directly generate high-frequency, low-phase-noise microwave signals. Crystal oscillators have extremely high quality factors, but their resonant frequencies are often low, requiring frequency doubling to bring the low-frequency signal to a higher frequency range. However, frequency doubling leads to severe phase noise degradation. Optoelectronic oscillators utilize long, low-loss optical fibers to construct a high-quality optoelectronic hybrid resonator, and the phase noise of the generated RF signal does not deteriorate with increasing microwave signal frequency. However, resonant cavities using long optical fibers are more susceptible to environmental temperature and noise, and the longer fibers result in smaller mode frequency spacing, making the optoelectronic oscillator prone to higher spurious emissions or even mode hopping, affecting its stability.

[0035] Terahertz signal generation can be divided into two categories: electronic schemes and photonic-assisted schemes. Electronic schemes can generate signals through mixing or direct generation. The former features high integration and high output power, while the latter has a wider output frequency range but lower output power. Electronic systems offer high transmission power, supporting long-distance wireless transmission, but suffer from significant harmonic interference, high phase noise, and poor frequency stability. Furthermore, the capacity of purely electronic systems is limited by the operating bandwidth and modulation efficiency of electronic devices. Photonic-assisted schemes can be further divided into optical heterodyne generation and direct generation based on the signal generation method. The former offers the advantage of flexible and tunable output frequency, while the latter boasts higher output power and a wider output frequency range, but requires a low-temperature operating environment.

[0036] In view of this, embodiments of the present invention provide a signal generating device, and the above-described signal generating device will be described below with reference to specific embodiments.

[0037] Figure 1 A schematic diagram of a signal generating apparatus according to a first embodiment of the present invention is shown.

[0038] like Figure 1 As shown, the signal generation device of this embodiment includes: at least two local oscillator lasers for generating at least two laser signals with different frequencies; an oscillation loop for oscillating based on the at least two laser signals with different frequencies to generate a first radio frequency signal corresponding to each laser signal; and a feedback controller, corresponding one-to-one with the local oscillator lasers, for generating a feedback signal based on the first radio frequency signal corresponding to each laser signal, and inputting the feedback signal to the corresponding local oscillator laser to adjust the frequency of the laser signal output by the local oscillator laser. Wherein, after the frequencies of the at least two laser signals generated by the at least two local oscillator lasers are locked to different resonant peaks corresponding to the optical filter in the oscillation loop, the optical filter is further used to output a first optical terahertz signal, the frequency of which is an integer multiple of the free spectrum range of the optical filter.

[0039] This device uses oscillation feedback to lock two local oscillator laser sources with different frequencies to the same optical reference, and can obtain high-quality terahertz signals through heterodyne detection.

[0040] It should be noted that the quality of the generated terahertz signal is limited by the stability of the optical filter, so an optical filter with high frequency stability is required.

[0041] Figure 2 A schematic diagram of a signal generating apparatus according to a second embodiment of the present invention is shown.

[0042] like Figure 2As shown, based on the signal generating device of the foregoing embodiment, the oscillation loop in the signal generating device of this embodiment may include:

[0043] An optical phase modulator, corresponding one-to-one with a local oscillator laser, is used to modulate the laser signal output by the corresponding local oscillator laser to obtain multiple modulated optical signals.

[0044] The second optical coupler is used to combine multiple modulator optical signals into a single line to obtain a merged signal.

[0045] An optical filter is used to perform concave filtering on the combined signal to obtain a concave-filtered optical signal.

[0046] The first photodetector is used to beat the dimmed filtered optical signal to obtain the second radio frequency signal.

[0047] The first radio frequency power divider is used to split the second radio frequency signal into at least two channels of the second radio frequency signal with equal power.

[0048] The first radio frequency filter corresponds one-to-one with the local oscillator laser. Each first radio frequency filter is used to filter one channel of second radio frequency signal to obtain the third radio frequency signal.

[0049] The first radio frequency amplifier corresponds one-to-one with the first radio frequency filter and is used to amplify the third radio frequency signal output by the corresponding first radio frequency filter to obtain the first radio frequency signal; the frequency of the first radio frequency signal is determined by the frequency of the corresponding local oscillator laser and the resonant peak angular frequency of the optical filter.

[0050] The second RF power divider corresponds one-to-one with the first RF amplifier. It is used to split the first RF signal into two first RF signals with equal power, and input one of the first RF signals into the corresponding optical phase modulator.

[0051] The feedback controller is used to generate a feedback signal based on another first radio frequency signal, and input the feedback signal into the corresponding local oscillator laser to adjust the frequency of the laser signal output by the local oscillator laser.

[0052] It should be noted that, Figure 2 The example described uses two local oscillator lasers, but the number of local oscillator lasers is not limited in this invention.

[0053] Figure 3 A schematic diagram of a signal generating apparatus according to a third embodiment of the present invention is shown.

[0054] like Figure 3 As shown, based on the above-described signal generating device, in the second embodiment of the present invention, the signal generating device may further include:

[0055] A first optical coupler, the input of which is connected to the output of at least two local oscillator lasers, is used to output a second optical terahertz signal after the frequencies of at least two laser signals generated by the at least two local oscillator lasers are locked to different resonant peaks corresponding to the optical filter. The frequency of the second optical terahertz signal is continuously adjustable.

[0056] Based on the above-described signal generating device, in the fourth embodiment of the present invention, the signal generating device may further include:

[0057] An optoelectronic frequency divider is located at the output end of an optical filter or the output end of a first optical coupler. It is used to perform optoelectronic conversion and frequency division on a first optical terahertz signal to obtain a first microwave signal, or to divide a second optical terahertz signal to obtain a second microwave signal.

[0058] Figure 4 The schematic diagram illustrates the spectral diagram and radio frequency spectrum diagram corresponding to each signal during the signal generation process according to an embodiment of the present invention.

[0059] like Figure 3 and Figure 4 As shown, taking two local oscillator lasers as an example, in the optical terahertz signal generation link, two local oscillator lasers with different frequencies are locked to the transmission peaks of different frequencies of the same reference optical filter. The locked two local oscillator lasers are combined through an optical coupler to obtain an optical terahertz signal with high frequency stability. The generated optical terahertz signal is then output through a photodetector beat frequency output to produce a terahertz signal with the same frequency stability.

[0060] In the link where the optical terahertz signal is generated, the two angular frequencies are respectively and The local oscillator lasers were respectively locked to the resonant peaks of different angular frequencies of the optical filter. and The local oscillator laser generates modulated optical signals after passing through phase modulators, which are then combined via optical couplers and input to an optical filter. Taking one path as an example, the upper sideband (frequency of...) of the modulated optical signal generated by the local oscillator laser... One of the resonant frequencies of the optical filter Equal, the light after being filtered by the optical filter's notch generates a beat frequency at the photodetector with the same frequency. The frequency of the generated radio frequency signal is determined by the angular frequency of the local oscillator laser. Resonant peak angular frequency with optical filter Decision, that is The radio frequency signal output from the photodetector is split into two paths by a radio frequency power divider. One path, after passing through radio frequency filter 1, retains only the frequency of... The radio frequency signal, after passing through the radio frequency coupler, is partly input to optical phase modulator 1, and partly used for feedback control of local oscillator laser 1. Similarly, local oscillator laser 2 generates a frequency of... The radio frequency signal. At this time, local oscillator lasers 1 and 2 are simultaneously locked at different resonant peaks of the optical filter.

[0061] The output optical terahertz signal can be directly output from the bandpass filter port of the optical filter, or it can be output from the local oscillator laser after being combined by an optical coupler. In the modulated optical signal generated by the local oscillator laser, the lower sideband frequency can also be equal to the resonant peak frequency of the optical filter.

[0062] It should be noted that in order to further reduce the impact of phase noise on the local oscillator laser source, it is necessary to ensure that the ratio of the delay of the optical filter to the radio frequency delay in the oscillation loop is as large as possible, that is, to increase the delay of the optical filter while reducing the delay of the radio frequency link.

[0063] Figure 5 A schematic diagram of a signal generating apparatus according to a fifth embodiment of the present invention is shown.

[0064] like Figure 5 As shown, based on the signal generating device of the foregoing embodiment, the oscillation loop in the signal generating device of this embodiment may include:

[0065] An optical phase modulator, corresponding one-to-one with a local oscillator laser, is used to modulate the laser signal output by the corresponding local oscillator laser to obtain multiple modulated optical signals.

[0066] A polarization modulator is used to adjust the polarization state of the modulated optical signal output by a portion of the optical phase modulator, so that the polarization state of the modulated optical signal after polarization adjustment is orthogonal to that of the modulated optical signal before polarization adjustment.

[0067] A polarization combiner is used to combine a modulated optical signal that has undergone polarization state adjustment with a modulated optical signal that has not undergone polarization state adjustment into a single signal, resulting in a combined signal.

[0068] An optical filter is used to perform concave filtering on the combined signal to obtain a concave-filtered optical signal.

[0069] A polarization beam splitter is used to split a concave-filtered optical signal into at least two concave-filtered optical signals.

[0070] The first photodetector corresponds one-to-one with the local oscillator laser. Each first photodetector is used to beat the filtered optical signal to obtain the second radio frequency signal.

[0071] The first radio frequency amplifier corresponds one-to-one with the first radio frequency filter and is used to amplify the third radio frequency signal output by the corresponding first radio frequency filter to obtain the first radio frequency signal; the frequency of the first radio frequency signal is determined by the frequency of the corresponding local oscillator laser and the resonant peak angular frequency of the optical filter.

[0072] The second RF power divider corresponds one-to-one with the first RF amplifier. It is used to split the first RF signal into two first RF signals with equal power, and input one of the first RF signals into the corresponding optical phase modulator.

[0073] The feedback controller is used to generate a feedback signal based on another first radio frequency signal, and input the feedback signal into the corresponding local oscillator laser to adjust the frequency of the laser signal output by the local oscillator laser.

[0074] It should be noted that, Figure 5 The example described uses two local oscillator lasers, but the number of local oscillator lasers is not limited in this invention.

[0075] Two local oscillator laser sources are simultaneously locked to an optical filter using polarization multiplexing. After passing through an optical coupler and a phase modulator, one path of the local oscillator laser source undergoes polarization state adjustment, causing the polarization state of the modulated optical signal to change by 90°, making it orthogonal to the polarization state of the other modulated optical signal (polarization state difference of 90°). This signal is then input to the optical filter after passing through a polarization combiner. The optical signal, after being filtered by the optical filter, is then separated into two orthogonal polarization states by a polarization beam splitter. These two beams are then input to photodetectors.

[0076] It should be noted that for details not covered in this embodiment, please refer to the foregoing embodiment section, which will not be repeated here.

[0077] Figure 6 A schematic diagram of a signal generating apparatus according to a sixth embodiment of the present invention is shown.

[0078] like Figure 6 As shown, based on the signal generating device of the foregoing embodiment, the oscillation loop in the signal generating device of this embodiment may include:

[0079] An optical phase modulator, corresponding one-to-one with a local oscillator laser, is used to modulate the laser signal output by the corresponding local oscillator laser to obtain multiple modulated optical signals.

[0080] The first optical wavelength division multiplexer is used to combine multiple modulated optical signals into one channel to obtain a combined signal.

[0081] An optical filter is used to perform concave filtering on the combined signal to obtain a concave-filtered optical signal.

[0082] The second optical wavelength division multiplexer is used to split the dimmed optical signal into at least two dimmed optical signals.

[0083] The first photodetector corresponds one-to-one with the local oscillator laser. Each first photodetector is used to beat the filtered optical signal to obtain the second radio frequency signal.

[0084] The first radio frequency amplifier corresponds one-to-one with the first radio frequency filter and is used to amplify the third radio frequency signal output by the corresponding first radio frequency filter to obtain the first radio frequency signal; the frequency of the first radio frequency signal is determined by the frequency of the corresponding local oscillator laser and the resonant peak angular frequency of the optical filter.

[0085] The second RF power divider corresponds one-to-one with the first RF amplifier. It is used to split the first RF signal into two first RF signals with equal power, and input one of the first RF signals into the corresponding optical phase modulator.

[0086] The feedback controller is used to generate a feedback signal based on another first radio frequency signal, and input the feedback signal into the corresponding local oscillator laser to adjust the frequency of the laser signal output by the local oscillator laser.

[0087] It should be noted that, Figure 6 The example described uses two local oscillator lasers, but the number of local oscillator lasers is not limited in this invention.

[0088] It should be noted that for details not covered in this embodiment, please refer to the foregoing embodiment section, which will not be repeated here.

[0089] Figure 7 A schematic diagram of a signal generating apparatus according to a seventh embodiment of the present invention is shown.

[0090] like Figure 7 As shown, based on the signal generating device of the foregoing embodiment, the oscillation loop in the signal generating device of this embodiment may include:

[0091] The third optical coupler is used to combine at least two laser signals with different frequencies into a single laser signal.

[0092] An optical phase modulator is used to modulate a single laser signal to obtain a modulated optical signal.

[0093] An optical filter is used to perform concave filtering on a modulated optical signal to obtain a concave-filtered optical signal.

[0094] The first photodetector is used to beat the dimmed filtered optical signal to obtain the second radio frequency signal.

[0095] The first radio frequency power divider is used to split the second radio frequency signal into at least two channels of the second radio frequency signal with equal power.

[0096] The first radio frequency filter corresponds one-to-one with the local oscillator laser. Each first radio frequency filter is used to filter one channel of second radio frequency signal to obtain the third radio frequency signal.

[0097] The first radio frequency amplifier corresponds one-to-one with the first radio frequency filter and is used to amplify the third radio frequency signal output by the corresponding first radio frequency filter to obtain the first radio frequency signal; the frequency of the first radio frequency signal is determined by the frequency of the corresponding local oscillator laser and the resonant peak angular frequency of the optical filter.

[0098] The second RF power divider corresponds one-to-one with the first RF amplifier and is used to split the first RF signal into two first RF signals with equal power.

[0099] The radio frequency combiner is used to combine the first radio frequency signal output by each of the second radio frequency power dividers into a fourth radio frequency signal, and input the second radio frequency signal into the optical phase modulator.

[0100] The feedback controller is used to generate a feedback signal based on another first radio frequency signal, and input the feedback signal into the corresponding local oscillator laser to adjust the frequency of the laser signal output by the local oscillator laser.

[0101] In this embodiment, the outputs of the two local oscillator lasers are combined via a third optical coupler. One path is used as the locked optical terahertz signal output, while the other is used for locking the local oscillator laser source with the optical filter. The combined optical signal is input to the optical phase modulator to generate a modulated optical signal. After filtering by the optical filter, the modulated optical signal is detected by a photodetector and outputs an oscillating radio frequency signal. The oscillating radio frequency signal is split into two paths by a radio frequency power divider. After passing through a radio frequency filter, only the frequency of the remaining path is equal to the difference between the angular frequency of the corresponding local oscillator laser and the resonant angular frequency of the optical filter. , The radio frequency (RF) signal is amplified and then split into two paths by an RF power divider. One path is used for feedback control of the local oscillator laser, and the other path is input to the RF port of the phase modulator after passing through an RF combiner.

[0102] It should be noted that, Figure 7 The example described uses two local oscillator lasers, but the number of local oscillator lasers is not limited in this invention.

[0103] It should be noted that for details not covered in this embodiment, please refer to the foregoing embodiment section, which will not be repeated here.

[0104] Continue to participate Figures 1-7 Based on the above embodiments, signal generation further includes:

[0105] The fourth optical coupler, located at the output of the optical filter, is used to split the first optical terahertz signal into two first optical terahertz signals.

[0106] The second photodetector is located at the output end of the fourth optical coupler or the output end of the first coupler. It is used to beat the first optical terahertz signal to obtain the first terahertz signal, or to beat the second optical terahertz signal to obtain the second terahertz signal.

[0107] Based on the above embodiments, the feedback controller generates a feedback signal based on the first radio frequency signal corresponding to the laser signal at each frequency, including: mixing the radio frequency reference signal with the first radio frequency signal, extracting the change in the center angular frequency of the local oscillator laser relative to the center angular frequency of the optical filter, obtaining an error signal, and generating a feedback signal based on the error signal.

[0108] Based on the signal generating apparatus provided in the above embodiments, embodiments of the present invention also provide a signal generating method.

[0109] Figure 8 A flowchart illustrating a signal generation method according to an embodiment of the present invention is shown schematically.

[0110] like Figure 8 As shown, the signal generation method includes operations S810 to S830.

[0111] When operating the S810, at least two laser signals with different frequencies are generated by at least two local oscillator lasers.

[0112] When operating S820, an oscillation loop is used to oscillate based on at least two laser signals of different frequencies to generate a first radio frequency signal corresponding to each laser signal of frequency.

[0113] In operation of S830, the feedback controller generates a feedback signal based on the first radio frequency signal corresponding to the laser signal of each frequency, and inputs the feedback signal to the corresponding local oscillator laser to adjust the frequency of the laser signal output by the local oscillator laser; the feedback controller corresponds one-to-one with the local oscillator laser.

[0114] Specifically, after at least two local oscillator lasers generate at least two laser signals whose frequencies are locked to different resonant peaks corresponding to the optical filters in the oscillation loop, a terahertz signal or a microwave signal is output.

[0115] It should be noted that for details not covered in this embodiment, please refer to the foregoing embodiment section, which will not be repeated here.

[0116] Figure 9 A phase noise diagram according to an embodiment of the present invention is illustrated schematically. Figure 10The diagram illustrates the phase noise measurement results when the beat frequency signal frequency interval is 10 GHz and 20 GHz according to an embodiment of the present invention.

[0117] like Figure 9 As shown, the phase noise of the locked beat frequency signal is lower than that of a single locked local oscillator laser, and much lower than that of the local oscillator laser before locking. Therefore, the generated terahertz or microwave signal has low phase noise. The phase noise of the microwave signal generated after N-fold division is reduced by 20*log10(N) dB. Therefore, the microwave signal after frequency division can also achieve low phase noise.

[0118] like Figure 10 As shown, the generated signal frequency has almost no effect on the phase noise. However, the bandpass-filtered optical signal output by the optical filter only contains signals with frequencies of... and The optical signal, specifically the optical terahertz signal, generates an angular frequency of [value missing] after being beat by a photodetector. Terahertz signals.

[0119] The flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of systems and methods according to various embodiments of the present invention. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of code containing one or more executable instructions for implementing the specified logical function. It should also be noted that in some alternative implementations, the functions indicated in the blocks may occur in a different order than those indicated in the drawings. For example, two consecutively indicated blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in a block diagram or flowchart, and combinations of blocks in a block diagram or flowchart, may be implemented using a dedicated hardware-based system that performs the specified function or operation, or using a combination of dedicated hardware and computer instructions.

[0120] Those skilled in the art will understand that the features described in the various embodiments and / or claims of the present invention can be combined or combined in various ways, even if such combinations or combinations are not explicitly described in the present invention. In particular, the features described in the various embodiments and / or claims of the present invention can be combined or combined in various ways without departing from the spirit and teachings of the present invention. All such combinations and / or combinations fall within the scope of the present invention.

[0121] The embodiments of the present invention have been described above. However, these embodiments are merely illustrative and not intended to limit the scope of the invention. Although various embodiments have been described above, this does not mean that the measures in the various embodiments cannot be used advantageously in combination. The scope of the invention is defined by the appended claims and their equivalents. Various substitutions and modifications can be made by those skilled in the art without departing from the scope of the invention, and all such substitutions and modifications should fall within the scope of the invention.

Claims

1. A signal generating device, characterized by include: At least two local oscillator lasers are used to generate at least two laser signals with different frequencies; An oscillating loop is used to oscillate based on at least two laser signals of different frequencies to generate a first radio frequency signal corresponding to each laser signal, including: an angular frequency of ω. LO1 In the modulated optical signal generated by the first laser signal, its upper sideband resonates with the resonant frequency w of the optical filter corresponding to the first laser signal. O1 Equally, the light after being filtered by the notch filter produces a beat frequency of w at the photodetector. RF1 The radio frequency signal has a frequency of w RF1 The radio frequency signal is sequentially passed through a first radio frequency power divider, a first radio frequency filter corresponding to the first laser signal, and a first radio frequency amplifier corresponding to the first radio frequency filter to obtain a first radio frequency signal corresponding to the first laser signal; and so on, to generate a first radio frequency signal corresponding to the laser signal at each frequency. A feedback controller, corresponding one-to-one with the local oscillator laser, is used to generate a feedback signal based on the first radio frequency signal corresponding to the laser signal at each frequency, and input the feedback signal to the corresponding local oscillator laser to adjust the frequency of the laser signal output by the local oscillator laser. Wherein, after the frequencies of at least two laser signals generated by the at least two local oscillator lasers are locked to different resonant peaks corresponding to the optical filter in the oscillation loop, the optical filter is also used to output a first optical terahertz signal, the frequency of which is an integer multiple of the free spectrum range of the optical filter.

2. The apparatus of claim 1, wherein, The device further includes: A first optical coupler, the input of which is connected to the output of the at least two local oscillator lasers, is used to output a second optical terahertz signal after the frequencies of the at least two laser signals generated by the at least two local oscillator lasers are locked to different resonant peaks corresponding to the optical filter. The frequency of the second optical terahertz signal is continuously adjustable.

3. The apparatus of claim 2, wherein, The device further includes: An optoelectronic frequency divider is disposed at the output end of the optical filter or the output end of the first optical coupler. It is used to perform optoelectronic conversion and frequency division on the first optical terahertz signal to obtain a first microwave signal, or to perform frequency division on the second optical terahertz signal to obtain a second microwave signal.

4. The device according to any of claims 1-3, characterized in that The oscillation loop includes: An optical phase modulator, corresponding one-to-one with the local oscillator laser, is used to modulate the laser signal output by the corresponding local oscillator laser to obtain multiple modulated optical signals; The second optical coupler is used to combine multiple modulator optical signals into one channel to obtain a combined signal. The optical filter is used to perform concave filtering on the combined signal to obtain a concave-filtered optical signal. A first photodetector is used to beat the dimmed filtered optical signal to obtain a second radio frequency signal. The first radio frequency power divider is used to split the second radio frequency signal into at least two second radio frequency signals with equal power. Each of the first radio frequency (RF) filters corresponds one-to-one with the local oscillator laser. Each first RF filter is used to filter one channel of the second RF signal to obtain the third RF signal. The first radio frequency amplifier corresponds one-to-one with the first radio frequency filter and is used to amplify the third radio frequency signal output by the corresponding first radio frequency filter to obtain the first radio frequency signal; the frequency of the first radio frequency signal is determined by the frequency of the corresponding local oscillator laser and the resonant peak angular frequency of the optical filter. The second RF power divider corresponds one-to-one with the first RF amplifier and is used to split the first RF signal into two first RF signals with equal power, and input one of the first RF signals into the corresponding optical phase modulator. The feedback controller is used to generate a feedback signal based on another first radio frequency signal, and input the feedback signal into the corresponding local oscillator laser to adjust the frequency of the laser signal output by the local oscillator laser.

5. The device of any one of claims 1-3, wherein, The oscillation loop includes: An optical phase modulator, corresponding one-to-one with the local oscillator laser, is used to modulate the laser signal output by the corresponding local oscillator laser to obtain multiple modulated optical signals; A polarization modulator is used to be installed at the output end of a portion of an optical phase modulator to adjust the polarization state of the modulated optical signal output by the corresponding optical phase modulator, so that the polarization state of the modulated optical signal after polarization state adjustment is orthogonal to that of the modulated optical signal before polarization state adjustment. A polarization combiner is used to combine a modulated optical signal that has undergone polarization state adjustment with a modulated optical signal that has not undergone polarization state adjustment into a single signal to obtain a combined signal. The optical filter is used to perform concave filtering on the combined signal to obtain a concave-filtered optical signal. A polarization beam splitter is used to split a notched filtered optical signal into at least two notched filtered optical signals. The first photodetector corresponds one-to-one with the local oscillator laser. Each first photodetector is used to beat the frequency of a channel of filtered optical signal to obtain a second radio frequency signal. The first radio frequency amplifier corresponds one-to-one with the first radio frequency filter and is used to amplify the third radio frequency signal output by the corresponding first radio frequency filter to obtain the first radio frequency signal; the frequency of the first radio frequency signal is determined by the frequency of the corresponding local oscillator laser and the resonant peak angular frequency of the optical filter. The second RF power divider corresponds one-to-one with the first RF amplifier and is used to split the first RF signal into two first RF signals with equal power, and input one of the first RF signals into the corresponding optical phase modulator. The feedback controller is used to generate a feedback signal based on another first radio frequency signal, and input the feedback signal into the corresponding local oscillator laser to adjust the frequency of the laser signal output by the local oscillator laser.

6. The device of any one of claims 1-3, wherein, The oscillation loop includes: An optical phase modulator, corresponding one-to-one with the local oscillator laser, is used to modulate the laser signal output by the corresponding local oscillator laser to obtain multiple modulated optical signals; The first optical wavelength division multiplexer is used to combine multiple modulated optical signals into one channel to obtain a combined signal; The optical filter is used to perform concave filtering on the combined signal to obtain a concave-filtered optical signal. The second optical wavelength division multiplexer is used to split the notched optical signal into at least two notched optical signals. The first photodetector corresponds one-to-one with the local oscillator laser. Each first photodetector is used to beat the frequency of a channel of filtered optical signal to obtain a second radio frequency signal. The first radio frequency amplifier corresponds one-to-one with the first radio frequency filter and is used to amplify the third radio frequency signal output by the corresponding first radio frequency filter to obtain the first radio frequency signal; the frequency of the first radio frequency signal is determined by the frequency of the corresponding local oscillator laser and the resonant peak angular frequency of the optical filter. The second RF power divider corresponds one-to-one with the first RF amplifier and is used to split the first RF signal into two first RF signals with equal power, and input one of the first RF signals into the corresponding optical phase modulator. The feedback controller is used to generate a feedback signal based on another first radio frequency signal, and input the feedback signal into the corresponding local oscillator laser to adjust the frequency of the laser signal output by the local oscillator laser.

7. The device of any one of claims 1-3, wherein, The oscillation loop includes: The third optical coupler is used to combine at least two laser signals with different frequencies into a single laser signal. An optical phase modulator is used to modulate a single laser signal to obtain a modulated optical signal. The optical filter is used to perform concave filtering on the modulated optical signal to obtain a concave filtered optical signal. A first photodetector is used to beat the dimmed filtered optical signal to obtain a second radio frequency signal. The first radio frequency power divider is used to split the second radio frequency signal into at least two second radio frequency signals with equal power. Each of the first radio frequency (RF) filters corresponds one-to-one with the local oscillator laser. Each first RF filter is used to filter one channel of the second RF signal to obtain the third RF signal. The first radio frequency amplifier corresponds one-to-one with the first radio frequency filter and is used to amplify the third radio frequency signal output by the corresponding first radio frequency filter to obtain the first radio frequency signal; the frequency of the first radio frequency signal is determined by the frequency of the corresponding local oscillator laser and the resonant peak angular frequency of the optical filter. The second RF power divider corresponds one-to-one with the first RF amplifier and is used to split the first RF signal into two first RF signals with equal power. The radio frequency combiner is used to combine the first radio frequency signals output by each of the second radio frequency power dividers into a fourth radio frequency signal, and input the second radio frequency signal into the optical phase modulator. The feedback controller is used to generate a feedback signal based on another first radio frequency signal, and input the feedback signal into the corresponding local oscillator laser to adjust the frequency of the laser signal output by the local oscillator laser.

8. The apparatus of claim 2, wherein, The device further includes: The fourth optical coupler is disposed at the output end of the optical filter and is used to split the first optical terahertz signal to obtain two first optical terahertz signals. The second photodetector is disposed at the output end of the fourth optical coupler or the output end of the first coupler, and is used to beat the first optical terahertz signal to obtain the first terahertz signal, or to beat the second optical terahertz signal to obtain the second terahertz signal.

9. The apparatus of claim 1, wherein, The feedback controller generates feedback signals based on the first radio frequency signals corresponding to laser signals of various frequencies, including: The radio frequency reference signal is mixed with the first radio frequency signal to extract the change in the center angular frequency of the local oscillator laser relative to the center angular frequency of the optical filter, thereby obtaining an error signal, and a feedback signal is generated based on the error signal.

10. A signal producing method characterized by comprising: The signal generation method is implemented based on the signal generation apparatus according to any one of claims 1-9, and the method includes: At least two laser signals with different frequencies are generated by at least two local oscillator lasers; An oscillating loop is used to oscillate based on at least two laser signals of different frequencies, generating a first radio frequency signal corresponding to each laser signal frequency. The feedback controller generates a feedback signal based on the first radio frequency signal corresponding to the laser signal at each frequency, and inputs the feedback signal to the corresponding local oscillator laser to adjust the frequency of the laser signal output by the local oscillator laser; the feedback controller corresponds one-to-one with the local oscillator laser. Specifically, after at least two local oscillator lasers generate at least two laser signals whose frequencies are locked to different resonant peaks corresponding to the optical filters in the oscillation loop, a terahertz signal or a microwave signal is output.

Images