CN107508127A - A kind of microwave photon signal frequency multiplication method and device with amplitude equalization effect - Google Patents

Abstract

The invention discloses a microwave photon signal frequency doubling method and device with amplitude equalization effect. The method utilizes the injection locking phenomenon and light-optical modulation in semiconductor lasers to realize frequency doubling and amplitude equalization of microwave photon signals; the method The devices used include light source and modulation device, polarization controller A, optical coupler A, optical circulator, semiconductor laser, adjustable optical delay line, optical bandpass filter, optical coupler B, polarization controller B and optical amplifier . The frequency multiplier of the present invention not only has the function of injection-locked frequency multiplication, but also balances the amplitude of the frequency-multiplied microwave photon signal, and at the same time, the working wavelength of the optical signal can realize broadband tunability. The invention improves the utilization rate of the device, has a simple structure and low cost ,easy to use.

Description

A microwave photon signal frequency doubling method and device with amplitude equalization effect

technical field

The invention relates to the field of communication technology, in particular to a microwave photon signal frequency multiplication method and device with an amplitude equalization effect.

Background technique

A frequency multiplier is a circuit that makes the output signal frequency equal to an integer multiple of the input signal frequency. The input frequency is f1, then the output frequency is f0=nf1, and the coefficient n is any positive integer, which is called the number of times of multiplication. The frequency multiplier has a wide range of uses, such as the transmitter can make the main oscillator oscillate at a lower frequency to improve frequency stability; the frequency multiplier is used to increase the frequency offset in the frequency modulation equipment; Among them, the frequency multiplier is an important component of the carrier recovery circuit.

Injection locking refers to the frequency effect that a simple harmonic oscillation is disturbed by another simple harmonic oscillation with a similar frequency. When the frequency of the second simple harmonic oscillation is close enough to the first one and the coupling is large enough, it will completely occupy the first oscillation, that is, the first oscillation follows the second oscillation. In the frequency doubler, when the frequency difference between a certain mode of the master laser and the free oscillation mode of the slave laser is not large, this mode can be effectively injected into the slave laser, and the free oscillation mode of the slave laser is suppressed, and its frequency and phase follow the master laser phenomenon of operation. The frequency range in which injection locking can occur is called the injection locking range. When the master laser carries an RF signal with frequency f and its N -order sideband falls within the injection-locked range of the slave laser, the optical signal is injected into the slave laser, and the frequency and phase of the slave laser follow the N -order sideband. The sideband is selectively amplified, that is, the signal light is frequency multiplied by N after injection locking.

However, there is a general disadvantage in the method of frequency doubling of microwave photonic signals relying on injection locking, that is, the interference of low-order harmonic components, which is manifested in the time domain as the amplitude of the N -time frequency signal is not flat. The existence of this shortcoming makes it difficult to directly apply the frequency multiplied signal of the existing injection-locked frequency multiplier in practice.

There have been extensive researches on this type of problem.

For example, there is a paper entitled "Peak equalization of rational-harmonic-mode-locking fiberized semiconductor laser pulse via optical injection induced gain modulation" in Optics Express, Vol.43, No. 2, pp. 850-859, 2009. The paper discloses a method for injecting a predistortion pulse train into a mode-locked laser to obtain a rational number frequency multiplied mode-locked signal output with balanced amplitude. In this method, the mode-locked laser itself can output a frequency-doubled microwave photon signal. Like the signal light injected into the locked output, the amplitude of the frequency-doubled signal is interfered by the low-order harmonic component, resulting in uneven signal amplitude. By injecting additional signal light into the ring laser, the frequency-doubled signal is shaped, so that the amplitude of the final output frequency-doubled signal is balanced. However, this method requires an additional laser, and the injected predistortion signal needs to be precisely controlled, increasing the cost and complexity.

In Acta Optics Sinica, Vol. 36, No. 3, 0306003, 2016, there is an article titled "Using Active Filters to Realize Equalization of Harmonic Mode-Locked Optical Pulses". This paper reports a method of injecting the multiplied frequency mode-locked signal with unbalanced amplitude into the active loop filter for secondary filtering to achieve amplitude flattening. In the active loop filter, the semiconductor optical amplifier is used as a gain medium and an optical-optical modulation device, and the optical delay line in the filter is tuned to change the free spectral range (FSR), the spectral components of a specific frequency interval pass, and other components are suppressed, Amplitude equalization of frequency doubled microwave photon signals is realized. However, such methods require the use of additional active devices, and the functions of the devices are not fully explored.

Therefore, the existing injection-locked frequency multiplier has the problem that the amplitude of the frequency-multiplied signal is not flat when multiplying the microwave photon signal, and the frequency-multiplied signal is difficult to be directly applied, and the device utilization of the existing injection-locked frequency multiplier is low. The cost is higher and the operation is complicated.

Contents of the invention

The object of the present invention is to provide a microwave photon signal frequency doubling method and device with amplitude equalization effect. The frequency multiplier of the present invention not only has the function of injection-locked frequency multiplication, but also balances the amplitude of the frequency-multiplied microwave photon signal, and at the same time, the working wavelength of the optical signal can realize broadband tunability. The invention improves the utilization rate of the device, has a simple structure and low cost ,easy to use.

The technical scheme of the present invention: a microwave photon signal frequency doubling method with amplitude equalization effect, characterized in that: the method uses the injection locking phenomenon and light-light modulation in semiconductor lasers to realize the frequency doubling and amplitude of microwave photon signals balanced.

In the aforementioned microwave photon signal frequency doubling method with amplitude equalization effect, the injection locking phenomenon is achieved by setting the wavelength of laser A , so that the Nth-order sideband of its modulated signal falls into the wavelength In the injection-locked region of the semiconductor laser, the N-order sideband is selectively amplified, and the injection-locked frequency doubling phenomenon of the microwave photon signal is realized.

In the aforementioned microwave photon signal frequency doubling method with amplitude equalization effect, the light-light modulation effect is to form an active ring filter by setting semiconductor lasers, optical delay lines and optical filters, and by adjusting the optical delay line, so that the frequency-spaced optical frequency comb passes through the active ring filter with maximum efficiency, and realizes the amplitude equalization of N-multiple microwave photon signals.

In the aforementioned microwave photon signal frequency doubling method with amplitude equalization effect, the wavelength of the optical filter , using the injection locking phenomenon and light-light modulation in semiconductor lasers to achieve frequency doubling and amplitude equalization of microwave photon signals.

The aforementioned device constructed by microwave photon signal frequency doubling method with amplitude equalization effect includes a light source and a modulation device, the light source and the modulation device are connected to the input end of the optical coupler A through the polarization controller A, and the output of the optical coupler A Port 1 of the optical circulator is connected to port 1 of the optical circulator, port 2 of the optical circulator is connected to the semiconductor laser, port 3 of the optical circulator is connected to the optical band-pass filter through an adjustable optical delay line, and the optical band-pass filter is connected to the optical coupling The input end of the optical coupler B is connected, the optical coupler B also includes an output port and a signal output port, the output port of the optical coupler B is connected to the polarization controller B, the polarization controller B is connected to the input end of the optical amplifier, and the optical amplifier The output end is connected with the input end of the optocoupler A.

In the aforementioned device, the light source and the modulation device are indirect modulation structures, including a laser A, the laser A is connected to the optical input end of the modulator, and the output end of the radio frequency source A is connected to the radio frequency input end of the modulator; the laser A is a wavelength tunable continuous light laser.

In the aforementioned device, the modulator is an electro-optic modulator, and the electro-optic modulator is a Mach-Zehnder modulator, a phase modulator or an electro-absorption modulator.

In the aforementioned device, the light source and the modulation device are direct modulation structures, including a laser B and a radio frequency source B, the output end of the radio frequency source B is connected to the radio frequency input end of the laser B; the laser B is a wavelength tunable semiconductor direct Modulate the laser.

In the aforementioned device, the semiconductor laser is a distributed feedback laser or a Fabry-Perot (F-P) cavity semiconductor laser.

In the aforementioned device, the optical amplifier is an erbium-doped optical fiber amplifier, a semiconductor optical amplifier or a fiber Raman amplifier.

Disconnect the connection between polarization controller B and coupler A, and adjust the wavelength of laser A (main laser) in the light source and modulation module , so that the Nth -order sideband of the output modulation signal of the module falls into the wavelength The injection-locked region of the semiconductor laser (that is, the slave laser). After injection locking, N -times frequency-multiplied microwave photon signals are obtained from the laser, but with low-order harmonic components.

Connect polarization controller B and coupler A to tune the center wavelength of the optical bandpass filter , only such that the wavelength is The light field passes through the filter and can form an oscillation in the ring cavity; at this time, the ring cavity is equivalent to an active ring filter: the optical amplifier provides gain for the oscillating light field; the nonlinear effect occurs in the semiconductor laser Light-to-light modulation, the wavelength is The light field is subject to , Modulation of two light fields. By adjusting the adjustable optical delay line and changing the length of the cavity, the FSR corresponding to the ring cavity changes, and only the optical frequency components of the frequency interval Nf pass through, while the optical frequency components of other intervals pf ( p=1,2,…, N-1 ) component is suppressed; finally, at the signal output of coupler B the wavelength is N -fold frequency amplitude equalization of microwave photonic signals.

Compared with the existing technology, the set semiconductor laser can not only realize injection-locked N -frequency multiplication as a slave laser, but also participate in the amplitude equalization of N -multiplication microwave photon signals as an optical-optical modulator in the ring cavity, fully The function of the device is called, the utilization rate of the device is improved, the structure is simple, and the cost is low; in addition, by setting the optical band-pass filter, the optical band-pass filter is an optical band-pass filter with adjustable center wavelength, the filter The device can determine the wavelength of the final frequency multiplied optical signal, so the working wavelength of the optical signal can be tunable in broadband. In summary, the frequency multiplier of the present invention not only has the function of injection-locked frequency multiplication, but also has the amplitude balance of the frequency-multiplied microwave photon signal, and at the same time, the working wavelength of the optical signal can realize broadband tunability, and the present invention improves the utilization rate of the device. The structure is simple, the cost is low, and the operation is simple.

Description of drawings

Fig. 1 is the structural representation of embodiment 1 of the present invention;

Fig. 2 is the structural representation of embodiment 2 of the present invention;

Fig. 3 is a schematic diagram of the principle of achieving N -multiplied frequency after the microwave photon signal is injection-locked.

The marks in the drawings are: 1-light source and modulation device, 1a-laser A, 1b-modulator, 1c-radio frequency source A, 1d-laser B, 1e-radio frequency source B, 2-polarization controller A, 3- Optical coupler A, 4-optical circulator, 4a-port one, 4b-port two, 4c-port three, 5-distributed feedback laser, 6-adjustable optical delay line, 7-optical bandpass filter, 8 - optical coupler B, 9 - polarization controller B, 10 - erbium-doped fiber amplifier.

detailed description

The present invention will be further described below in conjunction with the accompanying drawings and embodiments, but not as a basis for limiting the present invention.

Example 1. A microwave photon signal frequency doubling method and device with amplitude equalization effect, as shown in Figure 1 and Figure 3, the method is to use the injection locking phenomenon and light-light modulation in semiconductor lasers to realize the frequency doubling and Balanced amplitude.

The injection locking phenomenon is achieved by setting the wavelength of laser A , so that the Nth-order sideband of its modulated signal falls into the wavelength In the injection-locked region of the semiconductor laser, the N-order sideband is selectively amplified, and the injection-locked frequency doubling phenomenon of the microwave photon signal is realized; the light-light modulation effect is constituted by setting a semiconductor laser, an optical delay line and an optical filter. The source ring filter, by adjusting the optical delay line, makes the optical frequency comb of the frequency interval pass through the active ring filter with maximum efficiency, and realizes the amplitude equalization of the N-fold frequency microwave photon signal; the wavelength of the optical filter , using the injection locking phenomenon and light-light modulation in semiconductor lasers to achieve frequency doubling and amplitude equalization of microwave photon signals.

The device constructed by the microwave photon signal frequency multiplication method with amplitude equalization effect includes a light source and a modulation device 1, the light source and the modulation device 1 are connected to the input terminal 3a of the optical coupler A3 through the polarization controller A2, and the optical coupler A3 The output terminal of the optical circulator 4 is connected with the port one 4a of the optical circulator 4, the port two 4b of the optical circulator 4 is connected with the semiconductor laser 5, the port three 4c of the optical circulator 4 is connected with the optical bandpass filter through the adjustable optical delay line 6 7 is connected, the optical bandpass filter 7 is connected to the input end of the optical coupler B8, and the optical coupler B8 also includes an output port 8a and a signal output port 8b, and the output port 8a of the optical coupler B8 is connected to the polarization controller B9, The polarization controller B9 is connected to the input end of the optical amplifier 10, and the output end of the optical amplifier 10 is connected to the input end 3b of the optical coupler A3.

The light source and modulating device 1 is an indirect modulation structure, including a laser A1a, the laser A1a is connected to the optical input end of the modulator 1b, and the output end of the radio frequency source A1c is connected to the radio frequency input end of the modulator 1b; the laser A1a is A wavelength tunable continuous optical laser; the semiconductor laser 5 is a distributed feedback laser or a Fabry-Perot F-P cavity semiconductor laser; the optical amplifier 10 is an erbium-doped optical fiber amplifier, a semiconductor optical amplifier or a fiber Raman amplifier.

The modulator 1b is an electro-optic modulator, and the electro-optic modulator is a Mach-Zehnder modulator, a phase modulator or an electro-absorption modulator.

How it works: First, disconnect polarization controller B9 from coupler A3. Laser A1a produces a wavelength of The light enters the input end of the modulator 1b, the light field is modulated by the RF signal of frequency f sent by the radio frequency source 1c, and the polarization controller A2 adjusts the wavelength to The polarization state of the optical field is injected into the wavelength of The distributed feedback laser 5; adjust the wavelength of laser A1a , so that its N -order sideband falls into the injection-locked range of the distributed feedback laser 5, and the port three 4c of the optical circulator 4 outputs a microwave photon signal with an envelope frequency of Nf ; at this time, it is affected by other optical sidebands, including There is interference of low-order harmonic components with frequency pf ( p=1,2,…,N-1 ) in the electric spectrum of the envelope signal, and the envelope amplitude is not flat. Then, connect the polarization controller B9 and the coupler A3, And the central wavelength of the tuned optical bandpass filter 7 is and . At this time, only the wavelength The optical field passes through the optical bandpass filter 7, and the feedback is injected into the distributed feedback laser 5 to form an oscillation in the ring cavity; the ring cavity is equivalent to an active ring filter: the optical amplifier provides gain for the oscillating light field; the distributed feedback The laser 5 is a light-light modulation device with a wavelength of The light field is subject to , The modulation of the two light fields; the adjustable optical delay line 6 adjusts the cavity length of the ring cavity; the optical bandpass filter 7 determines the working wavelength of the output light as ; The optical coupler B8 outputs the final light field; the polarization controller B9 adjusts the wavelength as The polarization state of the light field. Properly adjust the adjustable optical delay line 6 to change the length of the cavity, so that the FSR corresponding to the ring cavity changes, and only the optical frequency components of the frequency interval Nf pass through, while other intervals pf ( p=1,2,…,N-1 ) The optical frequency components are suppressed. Finally, the wavelength obtained at the signal output of the coupler B8 is N -fold frequency amplitude equalization of microwave photonic signals.

Example 2. A microwave photon signal frequency doubling method and device with amplitude equalization effect, as shown in Figure 2 and Figure 3, the method is to use the injection locking phenomenon and light-light modulation in semiconductor lasers to realize the frequency doubling and Balanced amplitude.

The injection locking phenomenon is achieved by setting the wavelength of laser A , so that the Nth-order sideband of its modulated signal falls into the wavelength In the injection-locked region of the semiconductor laser, the N-order sideband is selectively amplified, and the injection-locked frequency doubling phenomenon of the microwave photon signal is realized; the light-light modulation effect is constituted by setting a semiconductor laser, an optical delay line and an optical filter. The source ring filter, by adjusting the optical delay line, makes the optical frequency comb of the frequency interval pass through the active ring filter with maximum efficiency, and realizes the amplitude equalization of the N-fold frequency microwave photon signal; the wavelength of the optical filter , using the injection locking phenomenon and light-light modulation in semiconductor lasers to achieve frequency doubling and amplitude equalization of microwave photon signals.

The device constructed by the microwave photon signal frequency multiplication method with amplitude equalization effect includes a light source and a modulation device 1, the light source and the modulation device 1 are connected to the input terminal 3a of the optical coupler A3 through the polarization controller A2, and the optical coupler A3 The output terminal of the optical circulator 4 is connected with the port one 4a of the optical circulator 4, the port two 4b of the optical circulator 4 is connected with the semiconductor laser 5, the port three 4c of the optical circulator 4 is connected with the optical bandpass filter through the adjustable optical delay line 6 7 is connected, the optical bandpass filter 7 is connected to the input end of the optical coupler B8, and the optical coupler B8 also includes an output port 8a and a signal output port 8b, and the output port 8a of the optical coupler B8 is connected to the polarization controller B9, The polarization controller B9 is connected to the input end of the optical amplifier 10, and the output end of the optical amplifier 10 is connected to the input end 3b of the optical coupler A3; the semiconductor laser 5 is a distributed feedback laser or a Fabry-Perot F-P cavity semiconductor laser ; The optical amplifier 10 is an erbium-doped fiber amplifier, a semiconductor optical amplifier or a fiber Raman amplifier.

The light source and modulation device 1 is a direct modulation structure, including a laser B1d and a radio frequency source B1e, the output of the radio frequency source B1e is connected to the radio frequency input of the laser B1d; the laser B1d is a wavelength tunable semiconductor direct modulation laser.

Working principle: Laser B1d produces a wavelength of The light field is modulated by the RF signal of frequency f from the radio frequency source 1c. The output end of the semiconductor directly modulated laser 1d is connected to one end of the polarization controller A2. All the other are with embodiment 1.

Claims (10)

1. A kind of 1. microwave photon signal frequency multiplication method with amplitude equalization effect, it is characterised in that：This method is to utilize partly to lead The frequency multiplication and amplitude equalization of microwave photon signal are realized in injection locking phenomena and light-light modulation effect in body laser.
2. 2. a kind of microwave photon signal frequency multiplication method with amplitude equalization effect according to claim 1, its feature exist In：The injection locking phenomena is the wavelength by setting laser ASo that the N rank sidebands of its modulated optical signal fall into ripple It is a length ofSemiconductor laser injection ' locked ' zone, N ranks sideband be chosen amplification, realize the injection of microwave photon signal Lock frequency multiplication phenomenon.
3. 3. a kind of microwave photon signal frequency multiplication method with amplitude equalization effect according to claim 1, its feature exist In：The light-light modulation effect is by setting semiconductor laser, optical delay line and optical filter to form active loop filtering Device, by adjusting optical delay line so that the optical frequency comb of frequency interval by the active loop filter, is realized in maximum efficiency The amplitude equalizations of N frequency multiplication microwave photon signals.
4. 4. a kind of microwave photon signal frequency multiplication method with amplitude equalization effect according to claim 3, its feature exist In：The wavelength of the optical filter, made using the injection locking phenomena in semiconductor laser and light-light modulation With realizing the frequency multiplication and amplitude equalization of microwave photon signal.
5. 5. according to a kind of microwave photon signal frequency multiplication side with amplitude equalization effect described in claim 1-4 any claims The device of method structure, it is characterised in that：Including light source and modulating device（1）, light source and modulating device（1）Through Polarization Controller A （2）With photo-coupler A（3）Input（3a）Connection, photo-coupler A（3）Output end and optical circulator（4）Port one （4a）Connection, optical circulator（4）Port two（4b）With semiconductor laser（5）Connection, optical circulator（4）Port three（4c） Through adjustable optical delay line（6）With optical band pass filter（7）Connection, optical band pass filter（7）With photo-coupler B（8）Input Connection, the photo-coupler B（8）Also include output port（8a）And signal output port（8b）, photo-coupler B（8）Output end Mouthful（8a）With Polarization Controller B（9）Connection, Polarization Controller B（9）With image intensifer（10）Input connection, image intensifer （10）Output end and photo-coupler A（3）Input（3b）Connection.
6. 6. device according to claim 5, it is characterised in that：The light source and modulating device（1）For indirect modulation type knot Structure, including laser A（1a）, laser A（1a）With modulator（1b）Light input end connection, radio frequency source A（1c）Output end With modulator（1b）Rf inputs connection；The laser A（1a）For the continuous light laser of tunable wave length.
7. 7. device according to claim 6, it is characterised in that：The modulator（1b）For electrooptic modulator, the electric light is adjusted Device processed is Mach-Zehnder modulators, phase-modulator or electroabsorption modulator.
8. 8. device according to claim 5, it is characterised in that：The light source and modulating device（1）For direct modulation type knot Structure, including laser B（1d）With radio frequency source B（1e）, radio frequency source B（1e）Output end and laser B（1d）Rf inputs Connection；The laser B（1d）Laser is directly modulated for tunable wavelength semiconductor.
9. 9. device according to claim 5, it is characterised in that：The semiconductor laser（5）For distributed feedback laser Or Fabry-Perot（F-P）Cavity semiconductor laser.
10. 10. device according to claim 5, it is characterised in that：The image intensifer（10）For erbium-doped fiber amplifier, half Conductor image intensifer or fiber Raman amplifier.