JP4828376B2 - High frequency oscillation source - Google Patents

Description

  The present invention relates to a low-phase noise high-frequency oscillation source that oscillates a high-frequency signal in, for example, a microwave band or a millimeter wave band.

  As a conventional high-frequency oscillation source, to establish frequency synchronization with an amplifying unit having an active element for oscillation, a load resistor connected to the output side of the amplifying unit, and a resonance circuit connected to the input side of the amplifying unit There is an injection-locked oscillator including a reference signal source (see, for example, Non-Patent Document 1).

  The oscillation operation of this injection locked oscillator is as follows. While noise in the oscillator circuit is amplified by the active element, a part of the amplified power is returned to the active element by a reactance circuit such as a capacitor, inductor, and resonance circuit connected to each terminal of the active element. Then, the oscillation operation is performed by further amplifying the power by the active element.

  The oscillation power is output from the load resistor, but when there is no injection signal, the oscillation frequency of the high-frequency oscillation source is roughly determined by the resonance frequency of the resonance circuit, and the phase noise largely depends on the load Q value of the resonance circuit. . When the signal of the reference signal source is injected, the oscillation frequency is synchronized with the frequency of the reference signal source, and phase noise equivalent to the signal of the reference signal source is obtained.

"A 60-GHz-band Subharmonically Injection Locked VCO MMIC Operating over Wide Temperature Range", 2005 IEEE MTT-S International Microwave Symposium Digest, TH3A-2, June 2005.

  In the conventional high-frequency oscillation source, when there is no low-phase noise reference oscillation source that becomes an injection signal, the phase noise largely depends on the load Q value of the resonance circuit. A high Q resonant circuit is required. However, since it is difficult to realize a high-Q resonance circuit that can handle high-frequency electrical signals, there is a problem that it is difficult to reduce the phase noise of electrical signals when oscillating high-frequency electrical signals. It was.

  When injection locking is performed by injecting a signal from the reference signal source, since the phase noise depends on the phase noise of the injection signal, an oscillator that oscillates the injection signal with low phase noise is required. Therefore, mounting a crystal oscillator with low phase noise with a low oscillation frequency and multiplying the signal oscillated from the crystal oscillator to the desired frequency will generate many harmonics. It is difficult to obtain an oscillation frequency of

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a high-frequency oscillation source capable of reducing the phase noise of an electric signal without using a high-Q resonance circuit. .

The high-frequency oscillation source according to the present invention includes a light source having a frequency f ₁ , first to N-th delay devices connected to N (N is an integer of 1 or more) stages alternately to the output terminal of the light source, and the first to The first to N-th optical phase modulators that modulate the light wave delayed by the N-th delay device with the input oscillation wave, and the first to N-th optical phase modulators are _{supplied with} an oscillation wave of frequency fr. Microwave oscillation means for output, an O / E converter connected to the output terminal of the Nth optical phase modulator, and a passband (2N · f _r ) band connected to the O / E converter And a pass filter.

Further, the high frequency source in accordance with another invention, a light source of frequency f _l, and the optical filter passband f _l which is connected to the output terminal of the light source, a first delay circuit connected to said optical filter An optical phase modulator connected to the first delay device for modulating an optical wave delayed by the first delay device with an input oscillation wave; and a second delay connected to the optical phase modulator. And a delay circuit loaded reciprocating optical modulator having a filter and an optical filter having a passband (f ₁ + N · f _r ) and (f ₁ −N · f _r ) connected to the second delay unit, a microwave oscillator for outputting an oscillation wave having a frequency f _r to said delay circuit loading reciprocating light modulator, the O / E converter connected to the output terminal of the delay circuit loading reciprocating light modulator, the O a band-pass filter the pass band (2N · f _r) to / connected to E converter It includes those were.

  According to the present invention, it is possible to reduce the phase noise of an electric signal without using a high-Q resonance circuit.

Embodiment 1 FIG.
1 is a block diagram showing a configuration of a high-frequency oscillation source according to Embodiment 1 of the present invention. As shown in FIG. 1, in the high-frequency oscillation source according to the first embodiment, the delay devices 3 and the optical phase modulators 4 are alternately connected in a plurality of stages, the light source 1 is connected to the first delay device 3, and the final An O / E modulator 5 and a subsequent band pass filter 6 are connected to the optical phase modulator 4 in the stage.

  Here, a unit in which the delay unit 3 and the optical phase modulator 4 are alternately connected from the delay unit 3 in N (N is an integer of 1 or more) stages is configured, and the optical phase modulator 4 at the final stage of this unit is connected to the O phase modulator 4. An / E converter (optical / electrical converter) 5 and a subsequent band pass filter 6 are connected. The delay device 3 is mainly assumed to be a low-loss optical fiber, but other devices may be used as long as they cause a delay. The O / E converter 5 is generally considered to be a photodiode, but any O / E converter 5 may be used as long as it can demodulate a light wave modulated by a microwave to obtain a microwave signal. The band pass filter 6 may be a filter using a chip capacitor and a chip inductor, a filter using a pattern line, or the like.

Next, the operation will be described. Light wave frequency f _l which is output from the light source 1 is delayed by the first delay unit 3, and output to the optical phase modulator 4 leading to the next stage of the delay element 3. In the optical phase modulator 4 modulates the input signal delayed by the first delay device 3 in the oscillation wave having a frequency f _r inputted from the microwave oscillator 2, a frequency of the sum of the frequency of each signal (f _l + f _r ) And a signal having a difference frequency (f ₁ −f _r ) are generated and output to the delay unit 3 connected to the next stage.

The next-stage delay unit 3 delays the input signal from the previous-stage optical phase modulator 4 and outputs the delayed signal to the optical phase modulator 4 connected to the next stage. In this optical phase modulator 4, the signal input from the preceding delay device 3 is modulated by the oscillation wave input from the microwave oscillator 2, and the difference between the signal of the sum frequency (f ₁ + 2 · f _r ) in each signal is obtained. The signal of the frequency ( _fl- 2 * _fr ) is produced | generated. These signals are output to the delay unit 3 connected to the next stage of the optical phase modulator 4.

By repeating the above-described operation at each stage, the Nth optical phase modulator 4 modulates the input signal from the preceding delay unit 3 with the input signal from the microwave oscillator 2 and calculates the sum of the signals. generating a signal of frequency _{(f l + N · f r} ) of the signal and the difference frequency _{(f l -N · f r)} . These signals are input to the O / E converter 5 without going through the delay unit 3.

The O / E converter 5 mixes the signal of the sum frequency (f ₁ + N · f _r ) and the signal of the difference frequency (f ₁ −N · f _r ), and the difference frequency (2N · f 2). An output wave of f _r ) is obtained. This output wave is filtered by a band pass filter 6 having a pass band (2N · f _r ) connected to the next stage, and is output after removing excess frequency components.

  The optical phase modulator 4 at each stage adds the oscillation wave of the originally input microwave oscillator 2 and its phase noise PN in a coherent manner, but is sufficient for the input signal via the delay unit 3 as described above. By adding a delay, the phase noise PN is added incoherently. For this reason, the average power of the phase noise PN is suppressed as compared with the case of coherent addition. Therefore, by giving the delay N times, the phase noise is sequentially added incoherently, and a sufficient phase noise reduction effect can be obtained.

  The following equation (1) represents the phase noise PN when no delay is given to the signal, and the following equation (2) represents the phase noise PN when the delay is given as described above.

Where ω _m is the detuning angular frequency,

Is the root mean square with respect to the time of phase fluctuation.

The formula (1) and (2) As is clear from, by performing N times the delay by the delay unit 3, the phase noise PN in the output wave of the frequency 2N · f _r is the phase noise of an oscillation wave having a frequency f _r (10 LogN + 20 Log2) is added (when there is a sufficient delay in the above equation (2)). On the other hand, the phase noise PN when obtaining the oscillation wave of 2N times the frequency without giving a delay becomes a value obtained by adding the phase noise of the (20Log2N) of the oscillation wave having a frequency f _r, when given a delay, The phase noise PN will be improved by 10 LogN.

As described above, according to the first embodiment, the light source 1 a frequency f _l, a delay unit 3 and the optical phase modulator 4 are N stages connected alternately to an output terminal of the light source 1, the first the N-th and microwave oscillator 2 that outputs an oscillation wave having a frequency f _r in the optical phase modulator 4, the N-th connected to the optical phase modulator 4 O / E converter 5 and band connected thereto (2N Since the phase noise PN is added incoherently in the optical phase modulator 4 at each stage by providing the band pass filter 6 of f _r ), the phase noise can be obtained without using a high-Q resonance circuit. An oscillation wave having a frequency (2N · f _r ) with a reduced frequency can be obtained, and the phase noise of the high-frequency signal source can be reduced.

Embodiment 2. FIG.
FIG. 2 is a block diagram showing a configuration of a high-frequency oscillation source according to Embodiment 2 of the present invention. As shown in FIG. 2, the high frequency oscillation source according to the second embodiment, the first embodiment is, as microwave oscillation means for outputting an oscillation wave having a frequency f _r in the optical phase modulator 4 Nos. 1 through N relative to the first outputs from the first oscillation wave of each frequency f _r in the optical phase modulator 4 of the N has a microwave oscillator 2 of the N, single outputting an oscillation wave having a frequency f _r And a distributor 7 for distributing an output wave of the microwave oscillator 2 to N-th optical phase modulator 4 and outputting it to each of the first to N-th optical phase modulators 4.

That is, in the configuration shown in the first embodiment, a distributor 7 is connected to each optical phase modulator 4 interposed between the first delay device 3 and the O / E converter 5 instead of the microwave oscillator 2. is doing. Distributor 7 is connected microwave oscillator 2 both distributes the oscillation wave having a frequency f _r outputted from the microwave oscillator 2 to the optical phase modulator 4. In FIG. 2, the same reference numerals are given to the same or corresponding components as in FIG. 1, and description thereof is omitted.

Next, the operation will be described. Light wave frequency f _l which is output from the light source 1 is delayed by the first delay unit 3, and output to the optical phase modulator 4 leading to the next stage of the delay element 3. In the optical phase modulator 4, a signal input from the delay unit 3, and modulated by the oscillation wave having a frequency f _r which is input through the distributor 7, the sum of the frequency of each signal frequency (f _l + f and it generates a signal of the signal _r) and the frequency difference (f _l -f _r) and outputs to the delay unit 3 connected to the next stage.

The next-stage delay unit 3 delays the input signal from the previous-stage optical phase modulator 4 and outputs the delayed signal to the optical phase modulator 4 connected to the next stage. In the optical phase modulator 4, the signal input from the preceding delay device 3 is modulated by the oscillation wave input from the distributor 7, and the difference from the signal of the sum frequency (f ₁ + 2 · f _r ) in each signal. The signal of the frequency ( _fl- 2 * _fr ) is produced | generated. These signals are output to the delay unit 3 connected to the next stage of the optical phase modulator 4.

By repeating the above-described operation at each stage, the Nth optical phase modulator 4 modulates the input signal from the preceding delay unit 3 with the oscillation wave input from the distributor 7, thereby signal to generate the sum frequency _{(f l + N · f r} ) of the signal and the difference frequency _{(f l -N · f r)} , and output to the O / E converter 5.

The O / E converter 5 mixes the signal of the sum frequency (f ₁ + N · f _r ) and the signal of the difference frequency (f ₁ −N · f _r ), and the difference frequency (2N · f 2). An output wave of f _r ) is obtained. This output wave is filtered by a band-pass filter having a pass band (2N · f _r ) connected to the next stage, and is output after removing excess frequency components.

Phase noise PN in the oscillating wave of the frequency 2N · f _r has a value obtained by adding the phase noise of the (10LogN + 20Log2) in the oscillation wave having a frequency f _r, when obtaining the oscillation wave of 2N times the frequency without giving a delay Compared with the phase noise (= 20 Log2N), it is improved by 10 LogN.

  As described above, according to the second embodiment, the distribution of the oscillation wave of the microwave oscillator 2 to each optical phase modulator 4 interposed between the first delay device 3 and the O / E converter 5 is performed. Since the device 7 is provided, the same effect as in the first embodiment can be obtained without providing the microwave oscillator 2 in the high-Q resonance circuit or the optical phase modulator 4 in each stage.

Embodiment 3 FIG.
FIG. 3 is a block diagram showing a configuration of a high-frequency oscillation source according to Embodiment 3 of the present invention. As shown in FIG. 3, the high-frequency oscillation source according to the third embodiment includes an optical filter 8a that inputs a light wave from the light source 1, a delay device 8b that delays a passing signal of the optical filter 8a, and a light wave that is delayed by the delay device 8b. Is modulated with an oscillation wave input from the microwave oscillator 2, an optical filter 8d for inputting the optical wave modulated by the optical phase modulator 8c, and an O / E converter 5 for inputting the output of the optical filter 8d. And a band-pass filter 6 connected thereto. Reference numerals 8a to 8d form one unit and are called a delay circuit loaded reciprocating optical modulator 8 loaded with a delay circuit.

Further, as shown in FIG. 3, the optical filter 8a, passes the signal of frequency f _l is the optical filter 8d, the frequency _{(f l + N · f r} ) and the frequency (f _l -N · f _r) and the The signal passes.

Next, the operation will be described. Light wave frequency f _l which is output from the light source 1 is inputted to the optical filter 8a, and output to the delay unit 8b connected to the next stage through the optical filter 8a. The delay unit 8b delays the input signal from the optical filter 8a and outputs the delayed signal to the optical phase modulator 8c connected to the next stage.

In the optical phase modulator 8c, a light wave of a frequency f _l which is input via a delay unit 8b, and modulated by the oscillation wave having a frequency f _r from the microwave oscillator 2, a frequency of the sum of the frequency of each signal (f _l + F _r ) signal and difference frequency (f ₁ −f _r ) signal are generated and output to the optical filter 8d connected to the next stage. In this way, by providing a delay at each stage and inputting it to the optical phase modulator 8c, the phase noise is added incoherently, and is suppressed compared to when the average power of the phase noise is added coherently.

Further, the optical filter 8d frequency _{(f l + N · f r} ), passed through a signal _{(f l -N · f r)} , the optical filter 8b passes the signal of frequency f _l. For this reason, the signals of the frequencies (f ₁ + f _r ) and (f ₁ −f _r ) from the optical phase modulator 8 c are returned to the optical filter 8 b and delayed again, and the delayed signal is reduced by the optical phase modulator 8 c. It is modulated by the oscillation wave having a frequency f _r from a wave oscillator 2.

In this way, signals of frequencies other than the passbands of the optical filters 8a and 8d reciprocate between the optical filters, resulting in signals of frequencies (f ₁ + N · f _r ) and (f ₁ −N · f _r ). The signal is modulated with a delay. At this time, since the phase noise PN is added incoherently every time it is modulated by the optical phase modulator 8c, a sufficient phase noise reduction effect can be obtained.

Delay and modulation is repeated N times modulated frequency _{(f l + N · f r} ), modulated wave (f _l -N · f _r) is input through the optical filter 8d to the O / E converter 5 Is done. The O / E converter 5 mixes the signal of the sum frequency (f ₁ + N · f _r ) and the signal of the difference frequency (f ₁ −N · f _r ), and the difference frequency (2N · f 2). An output wave of f _r ) is obtained. This output wave is filtered by a band-pass filter having a pass band (2N · f _r ) connected to the next stage, and is output after removing excess frequency components.

Phase noise PN in the oscillating wave of the frequency 2N · f _r has a value obtained by adding the phase noise of the (10LogN + 20Log2) in the oscillation wave having a frequency f _r, when obtaining the oscillation wave of 2N times the frequency without giving a delay Compared with the phase noise (= 20 Log2N), it is improved by 10 LogN.

As described above, according to the third embodiment, the optical filter 8a for entering light waves from a light source 1 of the frequency f _l, delayer 8b for delaying the passage signal of the optical filter 8a, delayed by the delay element 8b An optical phase modulator 8c that modulates an optical wave with an oscillation wave from the microwave oscillator 2, a delay unit 8b that delays the output of the optical phase modulator, and a signal in a predetermined band from the optical wave delayed by the delay unit 8b. Since the optical filter 8d, the O / E converter 5 that demodulates the output of the optical filter 8d into a microwave, and the band-pass filter 6 that passes only a signal in a predetermined band from the output of the O / E converter 5 are provided. An oscillation wave having a frequency (2N · f _r ) with reduced phase noise can be obtained without providing a Q resonance circuit or a plurality of stages of delay devices 8b and optical phase modulators 8c. Noise Rukoto can.

Embodiment 4 FIG.
4 is a block diagram showing a configuration of a high-frequency oscillation source according to Embodiment 4 of the present invention. As shown in FIG. 4, the high-frequency oscillation source according to the fourth embodiment is different from the configuration according to the third embodiment in that an injection locking oscillator 12 is used instead of connecting the microwave oscillator 2 to the delay circuit loaded reciprocating optical modulator 8. connect to connect the distributor 9 to the bandpass filter 6, to connect one of the distribution signals to 1 / (2N) divider 10, a frequency dividing circuit 10, a signal of a frequency f _r is passed The harmonics are connected to the low-pass filter 11 that blocks the harmonics, and the output of the low-pass filter 11 is input to the injection locked oscillator 12.

The injection locked oscillator 12 outputs a signal having the same frequency as the input signal to the reciprocating optical modulator 8 loaded with a delay circuit in synchronization with the frequency of the input (injected) signal. Divider 10 is converted by the O / E converter 5, to extract a portion of the signal power of a frequency 2N · f _r is the output wave is filtered by the band pass filter 6 low-pass filters 11 and this To the injection-locked oscillator 12 connected to. In FIG. 4, the same or corresponding components as those in FIG.

Next, the operation will be described. Light wave frequency f _l which is output from the light source 1 is input into Reciprocating optical modulator 8 loaded with delay circuit. In Reciprocating optical modulator 8, the frequency _{(f l + N · f r} ), is modulated while being given a delay until the signal _{(f l -N · f r)} . At this time, since the phase noise PN is added incoherently every time it is modulated by the optical phase modulator 8c, a sufficient phase noise reduction effect can be obtained.

The light wave output from the reciprocating optical modulator 8 loaded with the delay circuit is input to the O / E converter 5. In the O / E converter 5, the signal of the frequency (f ₁ + N · f _r ) and the signal of the frequency (f ₁ −N · f _r ) are mixed, and the difference frequency (2N · f _r ) is mixed. An output wave is obtained. This output wave is filtered by a band-pass filter 6 having a pass band (2N · f _r ) connected to the next stage, and is output to a distributor 9 after removing excess frequency components.

Phase noise PN in the oscillating wave of the frequency 2N · f _r has a value obtained by adding the phase noise of the (10LogN + 20Log2) in the oscillation wave having a frequency f _r, when obtaining the oscillation wave of 2N times the frequency without giving a delay Compared with the phase noise (= 20 Log2N), it is improved by 10 LogN.

Also, if you enter a portion of the distributed signal distributor 9 to the divider 10, the divider 10 extracts a signal of a frequency f _r the signal by 2N dividers. At this time, the signal of the frequency f _r, since not given a delay, the phase noise is lower by 20Log2N.

Therefore, the phase noise PN frequency f _r of the signal outputted from the frequency divider 10, (phase noise + 10LogN + 20Log2 signal of the original frequency _{f r) - (20Log2N) =} ( signal of the original frequency f _r the phase noise −10 LogN), which indicates that the phase noise has been sufficiently reduced.

The signal of the low phase noise frequency f _r, is injected into the injection-locked oscillator 12, phase noise of the oscillation wave output from the injection locked oscillator 12 is equal to the phase noise of the injected signal. For this reason, the phase noise PN is improved as described above. Further, by repeating this, the phase noise of the oscillation wave injected by the injection locking oscillator 12 can be further reduced.

As described above, according to the fourth embodiment, the injection-locked oscillator 12 is connected to the reciprocating optical modulator 8 loaded with the delay circuit, and the reciprocating optical modulator 8 is connected to the injection-locked oscillator 12. Since the frequency divider 10 that divides the output wave and applies feedback is provided, an oscillation wave having a frequency (2N · f _r ) with reduced phase noise can be obtained without using a high-Q resonance circuit. Therefore, it is possible to reduce the phase noise of the high-frequency signal.

Embodiment 5 FIG.
5 is a block diagram showing a configuration of a high-frequency oscillation source according to Embodiment 5 of the present invention. As shown in FIG. 5, the high-frequency oscillation source according to the fifth embodiment has a configuration in which the injection-locked oscillator 12 is replaced with a voltage-controlled injection-locked oscillator 13 in the configuration according to the fourth embodiment. The voltage-controlled injection-locked oscillator 13 uses a variable reactance element in the resonance circuit, and is an injection-locked oscillator that can vary the self-oscillation frequency by a control voltage applied from the outside by the control voltage source 14. The variable reactance element may be a variable capacitance element using a varactor diode.

  In the injection-locked oscillator 12, the self-excited oscillation frequency is fixed, and when the difference between the frequency of the input (injection) signal and the self-excited oscillation frequency of the injection-locked oscillator 12 is larger than the synchronization width, the injection lock cannot be established. . Since the voltage-controlled injection-locked oscillator 13 can vary the frequency of self-excited oscillation by the control voltage, the self-excited oscillation frequency can be matched with the frequency of the injection signal, and the synchronization width is not restricted. Further, within the range in which the oscillation frequency of the voltage-controlled injection-locked oscillator 13 can be varied, the multiplication number of the reciprocating optical modulator 8 loaded with the delay circuit and the frequency division number of the frequency divider 10 can be freely selected.

Embodiment 6 FIG.
6 is a block diagram showing a configuration of a high-frequency oscillation source according to Embodiment 6 of the present invention. As shown in FIG. 6, the high-frequency oscillation source according to the sixth embodiment is the same as the configuration according to the fifth embodiment, except that the voltage controlled injection locked oscillator 13 is combined with the phase comparator 15a and the reference signal source 15b. The synchronous oscillator 15 is configured.

  By providing the phase-locked oscillator 15, the frequency stability is increased, and the phase noise near the carrier can be reduced to the same level as that of the reference signal source 15b. Since the reference signal source 15b can use an element having excellent frequency stability such as a crystal oscillator, the frequency stability of the phase-locked oscillator 15 can be very high. In addition, at a high detuning frequency, the phase noise is incoherently added by the multiplication operation in the round-trip optical modulator 8 equipped with the delay circuit, and the phase noise is coherent by the frequency division operation in the frequency divider 10. The phase noise can be reduced by the effect that the reduction of the phase noise of 10 LogN is repeatedly performed by simple subtraction.

Embodiment 7 FIG.
FIG. 7 is a block diagram showing a configuration of a high-frequency oscillation source according to Embodiment 7 of the present invention. As shown in FIG. 7, the high-frequency oscillation source according to the seventh embodiment has a configuration in which a 1 / (2N) frequency divider 10 is connected to the subsequent stage of the bandpass filter 6 in the configuration according to the third embodiment shown in FIG. is there.

Which is the output of the bandpass filter 6 by dividing the frequency of f _r by the divider 10 a signal of a frequency (2N · f _r), the output signal of the same frequency as the frequency f _r of the microwave oscillator 2 can get. In this case, the frequency divider 10 phase noise PN signal of a frequency f _r which is output from the (original frequency f _r of the signal phase noise + 10LogN + 20Log2) - (20Log2N ) = ( signal of the original frequency f _r the phase Noise−10 LogN), which indicates that the phase noise has been sufficiently reduced. Therefore, an effect of reducing phase noise can be obtained in an output signal having the same frequency as the input signal. The final-stage frequency divider 10 is effective when applied to all cases of the first to sixth embodiments.

It is a block diagram which shows the structure of the high frequency oscillation source which concerns on Embodiment 1 of this invention. It is a block diagram which shows the structure of the high frequency oscillation source which concerns on Embodiment 2 of this invention. It is a block diagram which shows the structure of the high frequency oscillation source which concerns on Embodiment 3 of this invention. It is a block diagram which shows the structure of the high frequency oscillation source which concerns on Embodiment 4 of this invention. It is a block diagram which shows the structure of the high frequency oscillation source which concerns on Embodiment 5 of this invention. It is a block diagram which shows the structure of the high frequency oscillation source which concerns on Embodiment 6 of this invention. It is a block diagram which shows the structure of the high frequency oscillation source which concerns on Embodiment 7 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Light source, 2 Microwave oscillator, 3 Delay device, 4 Optical phase modulator, 5 O / E converter, 6 Bandpass filter, 7 Divider, 8 Round-trip optical modulator loaded with delay device, 8a Passband f _l optical filter, 8b delayer, 8c optical phase modulator, the optical filter 8d passband f _l + N · f _r and f _l -N · f _r, 9 distributor, 10 (1 / 2N) divider, 11 LPF, 12 injection locked oscillator of the pass band f _r, 13 voltage controlled injection locked oscillator, 14 a control voltage source, 15 a phase locked oscillator, 15a phase comparator, 15b reference signal source.

Claims (8)

A light source of frequency f ₁ ;
Oscillation waves to which light waves delayed by the first to Nth delay devices and the first to Nth delay devices connected to N (N: an integer of 1 or more) stages alternately are input to the output terminal of the light source 1st to Nth optical phase modulators that modulate at
A microwave oscillating means for outputting an oscillation wave having a frequency f _r to the optical phase modulator of the N from the first,
An O / E converter connected to an output terminal of the Nth optical phase modulator;
A high-frequency oscillation source comprising: a band-pass filter having a pass band (2N · f _r ) connected to the O / E converter. The high-frequency oscillation source according to claim 1,
Examples microwave oscillation means, the high frequency oscillation source, characterized in that it comprises a microwave oscillator of the first to N for outputting an oscillation wave of each frequency f _r to the optical phase modulator of the N from the first. The high-frequency oscillation source according to claim 1,
As the microwave oscillation means, a single microwave oscillator for outputting an oscillation wave having a frequency f _r, the outputs wave of the microwave oscillator to the N distribution to the optical phase modulator of the N from the first output A high-frequency oscillation source. A light source of frequency f _l,
Delay and optical filter passband f _l which is connected to the output terminal of the light source, a first delay circuit connected to said optical filter, connected to the first delay unit, by the first delay unit An optical phase modulator that modulates the input optical wave with an input oscillation wave, a second delay device connected to the optical phase modulator, and a passband ( _fl + N connected to the second delay device) A delay circuit loaded reciprocating optical modulator having an optical filter with f _r ) and (f ₁ −N · f _r );
A microwave oscillator for outputting an oscillation wave having a frequency f _r to said delay circuit loading Reciprocating light modulator,
An O / E converter connected to an output terminal of the delay circuit loaded reciprocating optical modulator;
A high-frequency oscillation source comprising: a pass-band (2N · f _r ) band-pass filter connected to the O / E converter. The high-frequency oscillation source according to claim 4,
The microwave oscillator is an injection locked oscillator,
A distributor connected to the output of the bandpass filter of the passband (2N · f _r ) and distributing the output in two;
A 1 / (2N) divider connected to one of the outputs of the distributor;
A high-frequency oscillation source, further comprising: a low-pass filter connected to the frequency divider, having a pass band of _fr , and an output of which is injected into the injection-locked oscillator. The high-frequency oscillation source according to claim 5,
A high-frequency oscillation source, wherein the injection-locked oscillator is a voltage-controlled injection-locked oscillator that can vary a self-excited oscillation frequency by an applied control voltage. The high-frequency oscillation source according to claim 6,
A phase comparator in which an input terminal is connected to a part of an output of the voltage-controlled injection-locked oscillator, and an output terminal is connected to a control terminal of the voltage-controlled injection-locked oscillator;
And a reference signal source connected to the phase comparator. A high frequency oscillation source, further comprising a 1 / (2N) frequency divider at a final output terminal of the high frequency oscillation source according to any one of claims 1 to 7.

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