JP2745234B2 - Frequency stabilized light source - Google Patents

Description

The present invention relates to a light source used in optical communication, and more particularly to a laser light source that stabilizes the frequency of output light.

(Prior Art) As a frequency stabilizing light source for stabilizing the frequency of output light of a laser light source, output light of a frequency reference light source and a stabilized light source is made incident on an optical resonator, and one of the resonance frequencies of the optical resonator And stabilizing the optical resonator by controlling the resonance frequency to be equal to the frequency of the reference light source, and stabilizing the frequencies of one to three stabilized light sources using the resonator. Proposed.

FIG. 1 shows the configuration of a frequency stabilizing light source using a conventionally proposed optical resonator. In the figure, 1 is a frequency reference light source,
20, 22, and 24 are stabilized light sources, 15 is an optical resonator, 80, 81, and
‥ 84,85 is a receiver, 91 is an optical resonator control device, 90,92, ‥‥ 9
4 is a stabilized light source control device. The broken line represents the flow of the optical signal, and the solid line represents the flow of the electric signal. Arrows indicate the direction in which the signal flows. L ₁ , L ₂₀ , L ₂₂ , ‥
‥ L ₂₄ is a frequency reference light source 1, a stabilized light source 20, 22,
‥‥ 24 output light, S ₈₀ , S ₈₁ , ‥‥ S ₈₄ , S ₈₅ are output signals of photodetectors ₈₀ , ₈₁ , ‥‥ ₈₄ , ₈₅ , respectively, S ₁₅ is optical resonator control device
Signal for 91 controls the optical resonator _{15, S 20, S 22,} ‥‥ S
₂₄ the stabilizing light source control device 90, 92, ‥‥ 94 respectively to be stabilized light source 20, 22 is a signal for controlling the ‥‥ 24.

Optical resonator controller 91 is modulated with the resonance frequency of the optical resonator 15 with a suitable amplitude and modulation frequency f _m. The output light L ₁ of the frequency reference source 1 is received by the photodetector 85 through the optical resonator 15. Suitable 1 f _rsr resonance frequency f _rs of the optical resonator 15 is made to be in the vicinity of the frequency f _fr of the frequency reference source. In the optical resonator control device 91, the signal _{S85 is changed} to the frequency f _m
To detect the difference between the reference frequency f _fr and the resonance frequency f _rsr, and control the optical resonator so that the two frequencies match. The stabilized light source 20, 22, the output of the ‥‥ 24 light L _20, L _22, ‥‥ L
₂₄ also passes through spatially different regions of the optical resonator and is received by the light receivers 80, 81, and 84. Stabilized light source
20,22, ‥‥ 24 are the appropriate resonance frequencies of optical resonator 15.
f _rs1, f _rs2, ‥‥ f is in the neighborhood of _rsn, the stabilizing light source control device 92, 92, ‥‥ 94 each of the stabilized light source 20, 22 by synchronous detection at the frequency f _m in, ‥‥ 24 And the corresponding resonance frequency are detected, and the frequencies of the stabilized light sources 20, 22, and 24 are controlled so that the two coincide with each other.

(Problems to be Solved by the Invention) In the above-mentioned conventional frequency stabilized light source, the light of the frequency reference light source and the light of the stabilized light source use spatially different regions of one resonator. , So that each light can be separated and received. Since the resonance frequency of an optical resonator is mainly determined by the optical path length of light in the resonator, any change that changes the optical path length will change the resonance frequency. One of the factors that change the optical path length is the condition of incidence on the optical resonator. In a resonator composed of two plane mirrors, the resonance frequency changes when the angle of incidence on the resonator changes. In a confocal optical resonator,
The resonance frequency depends on both the angle of incidence and the position of incidence. Furthermore, in the above-mentioned conventional frequency stabilized light source, the conditions for the incidence of the output light of the frequency reference light source to the optical resonator and the conditions for the incidence of the output light of each stabilized light source to the optical resonator do not always change the same. In addition, it is extremely difficult to stabilize the frequency of the stabilized light source to a high degree because these incident conditions may change over time or over time.

The present invention addresses this problem of conventional frequency stabilized light sources,
It is an object of the present invention to provide a more stable frequency stabilized light source which does not depend on the incident condition.

(Means for Solving the Problems) In order to achieve this object, a frequency stabilized light source according to the present invention uses a frequency reference light source to stabilize the frequencies of a plurality of stabilized light sources. In the light source, a plurality of frequency modulators having the same number as the total number of the frequency reference light source and the stabilized light source for frequency modulating the output light of the frequency reference light source and the stabilized light source; One optical coupler that combines the outputs of the plurality of frequency modulators, one optical interference system that interferes with the output of the optical coupler, and one photodetector that converts the output of the optical interference system into an electric signal A plurality of modulation signals corresponding to the plurality of frequency modulators, and an interference system control signal and an interference system control signal obtained from the optical interference system and the plurality of stabilized light sources in accordance with an electric signal output from the light receiver. Stabilized light source control Signal, the frequency difference between the reference frequency of the optical interference system corresponding to the frequency at which the transmittance of the optical interference system is maximum or minimum and the frequency of the output light from the frequency reference light source, and the plurality of stabilizations. And a control unit that controls the frequency difference between the frequency of the output light of the light source and the corresponding reference frequency of the optical interference system to be zero. An input-side directional coupler that divides into two outputs at the same ratio, an optical delay circuit that receives one output of the input-side directional coupler, and an optical path that receives the other output of the input-side directional coupler A length control unit, an output directional coupler that receives the outputs of the delay circuit and the optical path length control unit and divides the power of one input light into two outputs at substantially the same ratio, and the directional coupler on the input side. The optical delay circuit, the optical path length control unit, and the output An optical fiber for interconnection with directional coupler has a structure which is characterized in that is used.

(Operation) In the present invention, all test lights enter the optical interference system 7 under the same incident conditions, and all test lights propagate through substantially the same optical path in the optical interference system. Therefore, unlike the conventional light source device, the conditions under which the test light of the reference light source and the test light of the stabilized light source enter the optical interference system do not differ from each other.

 Hereinafter, embodiments will be described.

Embodiment 1 FIG. 2 shows a configuration of a first embodiment of the present invention. 1 is a frequency reference source, L ₁ is an output light, in this embodiment has also become the test light for monitoring the frequency of the optical interference system. 20,22, ‥‥ 24 are stabilized light sources, L ₂₀ , L
₂₂ and ‥‥ L ₂₄ are their output lights, and 40, 42 and ‥‥ 44 are light splitters, and output lights L ₂₀ , L ₂₂ ,
‥‥ L ₂₄ is converted to the output light L ₄₁ , L ₄₃ ,
And ‥‥ L _45, the test light L _40, L ₄₂ of each of the stabilized light source is divided into ‥‥ L _44. 3 frequency modulator for frequency modulating the test light L ₁ of the frequency reference source 1, L ₃ is a test light that is frequency modulated by the frequency modulator 3. 30, 32 and ‥‥ 34 are frequency modulators for frequency-modulating the test light L ₄₀ , L ₄₂ and ‥‥ L ₄₄ of the stabilized light source, respectively, and L ₃₀ , L ₃₂ and ‥‥ L ₃₄ are The test light is frequency-modulated by the frequency modulators 30, 32, and. Reference numeral 5 denotes an optical coupler that couples the frequency-modulated test lights L ₃ , L ₃₀ , L ₃₂ , and ΔL ₃₄ and outputs them from one optical fiber or substantially overlaps spatially. It is output as a single ray. L ₅ is output light of the optical coupler 5 and is introduced into the optical interference system 7. L ₇ is output light of the optical interference system 7, and 8 is one or a plurality of light receivers for receiving the output light. 9 is a control unit, the frequency modulator 3,30,32, ‥‥ 34 respectively frequency-modulated signal S _3, S _30, with S ₃₂ for frequency modulating the drive to test light by ‥‥ S _34, the light receiving receiving signal optical interference system from S ₈ 7 and the stabilization source 20, 22 output to the vessel 8, ‥‥ 24
Are extracted, and are controlled by the interference system control signal S ₇ , the stabilized light source control signals S ₂₀ , S ₂₂ , and ΔS ₂₄ , respectively. Connection between the components from the frequency reference light source 1 to the light receiver 8, and the respective stabilized light sources 20, 2
The connection between the components from 2, 24 to the light receiver 8 is made using spatially propagating light or an optical fiber.

Next, the operation of the control unit 9 and the method of frequency stabilization in this embodiment will be further described. For purposes of explanation, of the frequency at which the transmittance of the optical interference system 7 becomes maximum or minimum, the frequency of monitoring by the test light L ₁ and f _oir, the stabilization source 20, 22, the frequency of ‥‥ 24 f ₁₁ , f _12, the frequency at which the transmittance of the optical interference system 7 which is a reference to stabilize the ‥‥ f _1n is maximum or minimum _f oi1, f oi2, and ‥‥ f _oin. Also,
The frequency at which the transmittance of the optical interference system 7 is maximum or minimum is called the reference frequency of the optical interference system. Test light _{L 1, L 40, L 42} ,
The modulation frequencies f _fmr , f _fm1 , f of the periodic frequency modulation that ‥‥ L ₄₄ receives by the frequency modulators 3, 30, 32, and そ れ ぞ れ 34, respectively.
_fm2, by ‥‥ f _fmn is set so mutually differently, using a suitable means such as a filter, a signal corresponding to each test light controller 9 can be selectively extracted from the received signal S ₈ To do. The control unit 9 synchronously detects a signal component corresponding to each of the extracted test lights at the same frequency as that of the frequency-modulated signal that modulates the frequency of the test light by using a signal having an appropriate phase as a reference signal, thereby obtaining a frequency reference light source. Difference Δ between the frequency f _fr of the optical interference system and the reference frequency f _oir of the optical interference system
f _r , and frequency differences Δf ₁ , Δf ₂ , between the frequencies f ₁₁ , f ₁₂ , ‥‥ f _{1n of the} respective stabilized light sources and the corresponding reference frequencies f _oi1 , f _oi2 , ‥‥ f _oin of the optical interference system. Obtain information about ‥‥ and Δf _n .
Thus, in this embodiment, the frequency difference is adjusted by the interference control signals S ₇ an optical interference system 7 so as to zero the Delta] f _r, the reference frequency f of the optical interference system 7 relative to the frequency f _fr of the frequency reference light source 1 Stabilize _oir . Also, the frequency differences Δf ₁ , Δf ₂ ,
The frequency of the output light of each stabilized light source is adjusted by the stabilized light source control signals S ₂₀ , S ₂₂ and ‥‥ S ₂₄ so as to make ‥‥ Δf _n zero, and the reference frequency f _oi1 of the optical interference system 7 is _adjusted. , f _oi2 , ‥‥
Frequency f of stabilized light source 20, 22, ‥‥ 24 based on f _oin
11 , f ₁₂ and 12f _1n are stabilized.

Embodiment 2 FIG. 3 shows an embodiment of an optical interference system 7 using an optical fiber interference system for preserving the plane of polarization of light passing therethrough. 71 and 72 are directional couplers, 75 and 76 are two input terminals of the directional coupler 71, 750 and 760 are output terminals of the directional coupler 71, and 770 and 780 are input terminals of the directional coupler 72. , 77 and 78 are output terminals. The directional couplers 71 and 72 are optical directional couplers having a so-called coupling ratio of 1: 1 that output the power of light input from one input terminal from two output terminals at substantially the same ratio. 7
4 is an optical path length control unit, and 73 is a delay line. As the optical directional couplers 71 and 72, for example, an optical fiber directional coupler in which a region of an appropriate length of two optical fibers is arranged such that the cores of the optical fibers are close to each other can be used. Further, as the delay line 73, an optical fiber having an appropriate length can be used.

In the embodiment using such an optical interference system 7, the output light of the optical coupler 5 can be input from only one of the input terminals 75 and 76, or an appropriate number of output lights can be input. Can be input from the input terminal 75, and the rest can be input from the input terminal 76.

In the optical interference system as shown in FIG. 3, the light input from the input terminal 75 adjusts the frequency or the difference between the optical path length between the terminals 750 and 770 and the optical path length between the terminals 760 and 780, and By changing the reference frequency of the system, the output terminal
The output from 77 can be maximum (the output from 78 is minimum), and conversely, the output from output terminal 78 can be maximum (the output from 77 is minimum). Input terminal 76
The same applies to the light input from. Therefore, no matter what combination of test light is input from the two input terminals 75 and 76 of the optical directional coupler 71, only the specific test light is output from the output terminal 77 or 78 of the optical directional coupler 72. Can be output from any one of.

If a component that preserves the plane of polarization of light is used as the component shown in FIG. 3, it is possible to separate the light from the frequency reference light source and the light from the stabilized light source using the difference in the polarization plane. A frequency stabilized light source can be configured.

Embodiment 3 FIG. 4 shows an embodiment using the optical interference system shown in FIG. 3 and utilizing two inputs and two outputs of the optical interference system. Those corresponding to the various light sources, light splitters, and frequency modulators in FIG. 1 are not described. The test light of the frequency reference light source is input from the input terminal 76 of the directional coupler 71 and output from the output terminal 78 of the directional coupler 72. 80 and 81 are receivers, S
₈₀ and S81 are light receiving signals output from the light receivers ₈₀ and ₈₁ , respectively. An optical coupler 51 couples the modulated output of the stabilized light source. Other than these means the same as those in FIG. 2 and FIG. Test light L ₃ of the frequency reference source is input to the input terminal 75, the test light from the stabilization source is inputted from the input terminal 76. By adjusting the optical path length by the optical path length control unit 74, only test light derived from the frequency reference light source is output from the output terminal 77, for example, and all test light derived from the stabilized light source is output from the output terminal 78. , And separate them.

(Embodiment 4) FIG. 5 shows an embodiment in which separation between signals by the plane of polarization of test light is performed in the embodiment of FIG.
In the figure, reference numerals 10 and 11 denote polarization splitters, which divide incident light into two according to its polarization direction. 80, 81, 82, 83 are receivers, S ₈₀ , S
₈₁ , S82, and _S83 are light receiving signals output from the light receivers 80, ₈₁ , ₈₂ , and ₈₃ , respectively, and the others are the same as those in the previous figures. If there are only three stabilized light sources,
One polarization plane of the test light of the frequency reference light source and the test light of the stabilized light source are set to be orthogonal, and the polarization planes of the test light of the remaining two stabilized light sources are set to be orthogonal to each other. With this arrangement, it is possible to receive the test light after passing through the optical interference system with different light receivers.

(Embodiment 5) FIGS. 6, 7, and 8 show an embodiment of an optical path length control unit 74 made of an optical fiber or a polarization-maintaining optical fiber.
In the figure, 741 is a piezoelectric element or an electrostrictive element. Hereinafter, it is simply called a piezoelectric element. 742,743 are electrodes of the piezoelectric element 741. 740 is an optical fiber or a polarization maintaining optical fiber. Reference numeral 749 is a fixing base.

In the optical path length control unit 74 in FIG. 6, when a voltage is applied between the electrodes 742 and 743, the piezoelectric element 741 expands and contracts in the longitudinal direction. The optical fiber 740 is fixed to the piezoelectric element 741 along the longitudinal direction thereof. Therefore, since the optical fiber 740 expands and contracts according to the piezoelectric element, the optical path length for light passing through the optical fiber 740 can be controlled by adjusting the magnitude and direction of the voltage applied between the electrodes.

In the optical path length control unit 74 shown in FIG. 7, the piezoelectric element 741 is a laminated element, and one end is fixed to the optical fiber 740 at the contact 748, and the other end is fixed to the base. Optical fiber 740 is base 7
Both 49 are fixed at the contact 747. As in FIG. 6, the optical fiber 740 is expanded and contracted via the piezoelectric element by the voltage applied between the electrodes 742 and 743, and the optical path length is controlled.

In the optical path length control 74 shown in FIG. 8, a cylindrical piezoelectric element is used.
An optical fiber is wrapped around the 741 and fixed. As in FIG. 6, the optical fiber 740 is expanded and contracted via the piezoelectric element by the voltage applied between the electrodes 742 and 743, and the optical path length is controlled. That is, the piezoelectric element expands and contracts in the radial direction,
Control the optical path length.

The optical path length control unit as shown in FIGS. 6, 7, and 8 can also be used as a frequency modulator used in the present invention.
Assuming that the reference frequencies of the optical interference system are arranged at intervals of several tens of MHz to several hundreds of MHz, it is sufficient if the magnitude of the frequency shift of the frequency modulation applied to the test light is about several MHz. When the piezoelectric element is used near the resonance frequency of the mechanical vibration, such a frequency shift can be easily obtained. In addition, in the laminated piezoelectric element as shown in FIG. 7, a displacement of slightly less than 0.1 μm / V is obtained, so that a frequency shift of several MHz is obtained at an applied voltage of 100 V. Further, the same frequency shift can be obtained with a flat-plate-shaped piezoelectric element, and with a cylindrical piezoelectric element, the frequency shift is increased by the number of times of winding.

(Embodiment 6) FIG. 9 is an embodiment of the present invention in a case where the optical interference system 7 as shown in FIG. 3 is used and the separation between signals is performed by using a polarization filter by using a polarization filter. is there. It should be noted that there is only one stabilized light source, 26 in the figure. L ₂₆ is the output light of the stabilized light source 26, 46 is an optical splitter, is taken out of the test light L ₄ and the output light L ₄₇ as a stabilizing light source by dividing the output light L _26. 36 and 3 are the test light L _{46 of the} stabilized light source, respectively.
And the frequency of the test light L ₁ of the frequency reference source 1 is a frequency modulator for frequency modulation. S ₃₆ and S ₃ are the control unit 9
Are frequency modulation signals for driving the frequency modulators 36 and 3, respectively. L ₃₆ and L ₃ are test lights frequency-modulated by the frequency modulators ₃₆ and ₃ , respectively. L ₇₇ and L ₇₈ are output lights of the optical interference system, and 12 and 13 are polarization filters that transmit only light of a specific polarization plane in the incident light. L ₁₂ and L ₁₃ are output lights of the polarization filters 12 and 13, respectively, and ₈₆ and ₈₅ are light receivers, respectively, which receive the output lights L ₁₂ and L ₁₃ of the polarization filters and generate light reception signals S ₈₆ and S ₈₅ , respectively. Output. S ₇₄ is the optical path length control signals for driving the optical path length control section 74 is the same as the optical interference system control signal S ₇ in Figure 2. Further, S ₂₆ is to be stabilized light source control signal for controlling the frequency of the stabilized light source 26. In addition, symbols not described here have the same meanings as those in the previous drawings.

Therefore, in the present embodiment, the polarization planes of the two test lights incident on the optical interference system are set to be orthogonal to each other. Also,
Appropriately selecting a reference frequency for stabilizing the optical path length control unit 74 and the stabilized light source 26, the test light of the frequency reference light source is mainly output from the output terminal 78, and the test of the stabilized light source is output from the output terminal 77. Light is mainly output. Further, the polarization filters 12, 13 are used to remove other leaked test light components. Thereby, the performance as a stabilized light source is improved.

In the embodiment of FIG. 9, instead of using the frequency modulators 36 and 3, an optical path length control signal for driving the optical path length control unit 74 is used.
By keep superimposing an AC signal of appropriate frequency and amplitude to S _74, the equivalent effect as the frequency modulation is obtained test light.

In the present invention, ordinary optical resonators such as Fabry-Perot etalons and confocal etalons can also be used as the optical interference system. Further, a so-called optical fiber resonator in which a reflecting mirror made of a dielectric multilayer film is formed at both ends of an ordinary length of a normal optical fiber or a polarization-maintaining optical fiber, which is optically polished, may be used. Similar to the reference frequency of the optical interference system shown in FIG. 3, the resonance frequency of the optical fiber resonator hardly changes depending on the incident conditions. Therefore, as in a stabilized light source using a conventional optical resonator as a reference, the fluctuation of the frequency due to the incident condition can be suppressed to an extremely low level.

(Effects of the Invention) As will be understood from the above description, the following effects can be obtained by the present invention.

The conditions under which all test lights enter the optical interference system are the same.

Since all the test light propagates in the same optical path in the optical interference system, no difference occurs in the optical path for each test light.

Since the separation between the test lights is also performed by selecting the polarization plane, it is possible to extract a signal regarding the frequency difference between each test light and the reference frequency with a high degree of separation.

From these facts, the present invention realizes a frequency stabilized light source capable of extracting a plurality of output lights with high frequency stability with an extremely simple configuration.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a frequency stabilized light source based on a conventional resonator, FIG. 2 is a block diagram showing a configuration of an embodiment of the present invention, and FIG. 3 is an optical interference system used in the present invention. FIG. 4 is a block diagram showing an example of the configuration of FIG. 3, and FIG. 4 is an example of an input format of test light to the optical interference system and an output format of test light from the optical interference system when the optical interference system shown in FIG. 3 is used. FIG. 5 is a block diagram showing an example of an output format using a polarization separation element from an optical interference system, and FIG. 6 is a cross-sectional view showing an example of an optical path length control unit using an optical fiber. , Seventh
The figure is a side view showing an example of an optical path length control unit using an optical fiber, FIG. 8 is a perspective view showing an example of an optical path length control unit using an optical fiber, and FIG. FIG. 3 is a block diagram showing one embodiment of the present invention in the case of a plurality. 1 frequency reference light source, 3 frequency modulator for frequency-modulating the frequency of the test light of the frequency reference light source, 5.
Optical coupler group 6, coupling optical system 7, optical interference system 8,
…… Receiver, 9… Control unit, 10,11 …… Polarization separation element, 1
2,13 ... Polarization filter, 15 ... Optical resonator, 20,22, ... 24
…… Stabilized light source, 26 …… Stabilized light source, 30, 32,… 34
…… Frequency modulator for frequency-modulating the frequency of the test light of the stabilized light source, 36 …… Frequency modulator for frequency-modulating the frequency of the test light of the stabilized light source, 40,42,… 44
……………………………………………………………………………………………………………………………………………………………………………………………………………….
Optical path length control unit, 75, 76 ... Input terminal of directional coupler 71, 77, 78 ... Input terminal of directional coupler 72, 80, 81, 82, 83, ... 84 ... Receiver, 85 , 86 …… Receiver, 90 …… Stabilized light source control device, 91…
... Optical resonator control device, 92, ... 94 ... Stabilized light source control device, 740 ... Optical fiber or polarization-maintaining optical fiber, 741 ... Piezoelectric element (including electric conductive element), 742,743 ...
... Electrode of piezoelectric element 741, 745 ... Input terminal of optical fiber (optical path length controller), 746 ... Optical fiber (optical path length controller)
747, contact point between optical fiber 740 and base 749, 748 contact point between optical fiber 740 and piezoelectric element 741, 749
…… Base, 750,760 …… Output terminal of directional coupler 71, 77
Input terminal of 0,780 ...... directional coupler 72, L ₁ ...... frequency reference source of the output light and test light, L ₃ ...... frequency modulated frequency reference source of the test light, L ₅ ...... optical coupler group 5 output light, the output light of the L ₇ ...... optical interference system 7, the output light of the L _12, L ₁₃ ...... polarization filters _{12,13, L 20, L 22,} ...... L 24 ...... of the stabilization source of Output light, L ₂₆ …… Stabilized light source output light, L ₃₀ , L ₃₂ …… L
₃₄ …… Test light of frequency-modulated stabilized light source, L ₃₆ …
… Frequency-modulated test light of stabilized light source, L ₄₀ , L ₄₂ …
… L ₄₄ …… Test light of stabilized light source, L ₄₁ , L ₄₃ …… L ₄₅ ……
Output light as a frequency-stabilized light source, L ₄₆ …… Test light of a light source to be stabilized, L ₄₇ …… Output light as a frequency-stabilized light source, S ₃ …… A frequency modulation signal for driving a frequency modulator, S ₇
...... interference system control signal, an output for receiving signals S ₈ ...... photodetector 8, a signal for controlling the S ₁₅ ...... optical resonator, S _20, S ₂₂ ...
… S ₂₄ …… Stabilized light source control signal, S ₂₆ …… Stabilized light source control signal, S ₃₀ , S ₃₂ …… S ₃₄ …… Frequency modulation signal to drive the frequency modulator, S ₃₆ …… Frequency modulation Frequency modulation signal for driving the optical device, S ₇₄ ... Optical path length control signal for driving the optical path length control section, S ₈₀ , S ₈₁ , S ₈₂ , S ₈₃ ... S _84. , 82,83 …… 84
, S ₈₅ …… _Reception signal output from the receiver 85, S ₈₆ …… _Reception signal output from the receiver 86, f _fr …… Frequency of the frequency reference light source, f _fmr , f _fm1 , f _fm2 F _mfn frequency modulation frequency for modulating the test light, f _1s frequency of the stabilized light source, f ₁₁ , f ₁₂ , f _1n frequency of the stabilized light source, f _m Modulation frequency, f, that modulates the resonance frequency of the optical resonator
_oi ...... optical interference system of the reference frequency, f _oir ...... frequency reference source by the reference frequency of the optical interference system to be _monitored, f oi1, f oi2, a reference to stabilize the target-stabilized light source ...... f _oin ...... Reference frequency of optical interference system, f _rs ……
Resonance frequency of the optical resonator, the resonance frequency of the optical resonator monitored by f _rsr ...... frequency reference _{source, f rs1, f rs2, ......} f rsn
... The common frequency of the optical resonator as a reference for stabilizing the stabilized light source, Δf _r ... The difference between the frequency f _fr of the frequency reference light source and the reference frequency f _oir of the optical interference system, Δf ₁ , Δf ₂ , Δf _n ... The difference between the frequency of the stabilized light source and the reference frequency selected as a reference for stabilizing the frequency.

Claims (2)

(57) [Claims] 1. A frequency stabilized light source for stabilizing the frequencies of a plurality of stabilized light sources using one frequency reference light source, wherein the frequency reference light source and the output light of the stabilized light source are frequency-modulated. A plurality of frequency modulators having the same number as the total number of the frequency reference light source and the stabilized light source; one optical coupler coupling outputs of the plurality of frequency modulators; and An optical interference system that interferes with the output of the optical interferometer, an optical receiver that converts the output of the optical interference system into an electric signal, and a plurality of modulation signals corresponding to the plurality of frequency modulators. An interference system control signal and a plurality of stabilized light source control signals obtained according to an electric signal output from the light receiver are sent to the interference system and the plurality of stabilized light sources, and the transmittance of the optical interference system is maximum or minimum. The light corresponding to a frequency The frequency difference between the reference frequency of the interference system and the frequency of the output light from the frequency reference light source and the frequency difference between the frequency of the output light of the plurality of stabilized light sources and the corresponding reference frequency of the optical interference system are set to zero. And a control unit for controlling the optical interference system, and the optical interference system has an input-side directional coupler that divides the power of one input light into two outputs at substantially the same ratio, and a directional coupler on the input side. An optical delay circuit for receiving one output of the optical device, an optical path length control unit for receiving the other output of the directional coupler on the input side, an output of the delay circuit and the optical path length control unit, and a power of one input light. Directional coupler on the output side, which divides the directional coupler into two outputs at substantially the same ratio; interconnection of the directional coupler on the input side, the optical delay circuit, the optical path length control unit, and the directional coupler on the output side It is characterized by using optical fiber and Frequency-stabilized light source to. 2. The apparatus according to claim 1, wherein a polarization separation element is disposed between said optical interference system and said light receiver.
The frequency stabilized light source according to the item.