CN210326461U

CN210326461U - Low-phase noise photoelectric oscillator

Info

Publication number: CN210326461U
Application number: CN201921492794.2U
Authority: CN
Inventors: 于晋龙; 马闯
Original assignee: Nanjing Hetai Photoelectric Technology Co ltd
Current assignee: Nanjing Hetai Photoelectric Technology Co ltd
Priority date: 2019-09-09
Filing date: 2019-09-09
Publication date: 2020-04-14
Anticipated expiration: 2029-09-09

Abstract

The utility model discloses a low phase noise optoelectronic oscillator, phase modulator pass through first polarization controller and second polarization controller and connect laser instrument and polarization beam splitter respectively, laser instrument output direct current light signal gets into phase modulator through first polarization controller, the light signal after the phase modulator modulation is incided into polarization beam splitter through second polarization controller, adjust second polarization controller and make the light signal 45 degrees angle get into polarization beam splitter, phase signal converts two way intensity signal that power equals; the utility model discloses the photoelectric oscillator of structure only satisfies the mode that inside first loop decided and the signal of the mode that the second loop decided simultaneously just can the oscillation starting, and other modes have obtained good suppression, can obtain single longitudinal mode output, and suppression side mode that not only can be better combines double balance photoelectric detector can restrain and fall the loop common mode noise including laser instrument relative strength noise, guarantees output signal's signal quality.

Description

Low-phase noise photoelectric oscillator

Technical Field

The utility model relates to a microwave technique and optoelectronics technical field especially relate to a low phase noise optoelectronic oscillator.

Background

The photoelectric oscillator is a kind of optical, electric microwave/millimeter wave signal generator, and its basic structure is a feedback loop formed by light source, photoelectric modulator, photoelectric detector and electric filter, but one of the main problems of the photoelectric oscillator system is the contradiction between high Q value of signal and side mode suppression.

The existing solutions for solving the contradiction mainly include the following schemes, firstly, the multiple loop structure is adopted, and the multiple loop photoelectric oscillator structure of photoelectric mixing in the multiple loop structure has the problems that multiple sets of photoelectric conversion devices are used, and the noise of the system and the cost of the system are increased; the optical domain coupling multi-loop structure photoelectric oscillators in the multi-loop structure are divided into two types, one type is a polarization dual-loop OEO, and the scheme needs to carefully control the polarization states of two paths of optical fields in the cavity; one is a wavelength multi-loop OEO, which requires multiple lasers with different wavelengths and wavelength division multiplexers corresponding to the wavelengths, thus increasing the cost of the system to some extent, and the deterioration of the output signal will be aggravated by the jitter of the wavelengths of the multiple lasers; secondly, a cascade filtering mode is adopted, and the problems of overlarge insertion loss, poor tunability and extra increased cavity loss exist in the echo corridor filtering mode scheme in the cascade filtering mode, so that the Q value of the resonant cavity is reduced, and the phase noise of an output signal is deteriorated; the scheme has the defect of limited side mode inhibiting effect by embedding a ring filter or an F-P filter in an OEO resonant cavity; thirdly, side modes are inhibited by adopting injection locking and injection locking DFB laser, and the problem that the phase noise of an output signal is rapidly deteriorated exists; direct outside microwave signal injection optoelectronic oscillator, the phase noise that has the phase noise direct influence OEO output signal of injection signal makes its long chamber lose the problem of meaning, consequently the utility model provides a low phase noise optoelectronic oscillator to solve the weak point among the prior art.

SUMMERY OF THE UTILITY MODEL

To the above problem, the utility model provides a low phase noise optoelectronic oscillator, the utility model discloses the optoelectronic oscillator of structure only satisfies the mode of inside first loop decision and the signal of the mode of second loop decision simultaneously just can start shaking, and other modes have obtained good suppression, can obtain single vertical mode output, suppression limit mould that not only can be better, combines double balance photoelectric detector can restrain and falls the loop common mode noise including laser instrument relative strength noise, guarantees output signal's signal quality.

The utility model provides a low phase noise optoelectronic oscillator, including phase modulator, polarization beam splitter, first optical amplifier, second optical amplifier and two balanced photoelectric detector, the phase modulator passes through first polarization controller and second polarization controller and connects laser instrument and polarization beam splitter respectively, laser instrument output direct current light signal gets into the phase modulator through first polarization controller, the light signal after the phase modulator modulation is incident to polarization beam splitter through the second polarization controller, adjusts the second polarization controller makes light signal 45 degrees angle get into polarization beam splitter, phase signal conversion is two way intensity signal that the power equals, first optical amplifier and second optical amplifier connect two balanced photoelectric detector, intensity signal gets into two balanced photoelectric detector ports through optic fibre, tunable light extension line, second optical amplifier all the way, the other path of intensity signal enters a port of the double-balanced photoelectric detector through the optical fiber, the variable optical attenuator and the first optical amplifier to be converted into an electric signal, the electric signal is fed back through the microwave amplifier, the band-pass filter and the electric coupler, and the fed-back electric signal drives the phase modulator to form a closed-loop oscillation circuit.

The further improvement lies in that: the optical fiber comprises a first optical fiber and a second optical fiber, and the polarization beam splitter is respectively connected with the tunable optical extension line and the adjustable optical attenuator through the first optical fiber and the second optical fiber.

The further improvement lies in that: the phase modulator is a lithium niobate phase modulator.

The further improvement lies in that: the first optical amplifier and the second optical amplifier are both semiconductor optical amplifiers.

The further improvement lies in that: the second optical fiber is connected with the first optical amplifier through the adjustable optical attenuator.

The utility model has the advantages that: the utility model discloses the photoelectric oscillator of structure only satisfies the signal of the mode of inside first loop decision and the mode of second loop decision simultaneously and just can start shaking, other modes have obtained good suppression, single longitudinal mode output can be obtained, the chamber length through tunable light extension line matching first loop and second loop, can select required start shaking mode in the band-pass filter bandwidth, the loss of whole loop has been reduced through phase modulator's use, the Q value of loop has been increased, the output of high quality signal has been guaranteed, optical power that can guarantee a loop and second loop through adjusting tunable optical attenuator equals, the suppression side mode that not only can be better, combine double balance photoelectric detector can restrain and fall the loop common mode noise including laser instrument relative intensity noise, guarantee output signal's signal quality, working current through adjusting first optical amplifier and second optical amplifier can further restrain and get into double balance photoelectric detection and survey the entering The power of the signal of the device fluctuates to ensure output of a high quality signal.

Drawings

Fig. 1 is a schematic view of the structure of the present invention.

Wherein: 1. a phase modulator; 2. a polarizing beam splitter; 3. a first optical amplifier; 4. a second optical amplifier; 5. a double balanced photodetector; 6. a laser; 7. a first polarization controller; 8. a second polarization controller; 9. a tunable optical extension line; 10. a variable optical attenuator; 11. a microwave amplifier; 12. a band-pass filter; 13. an electric coupler; 14. a first optical fiber; 15. a second optical fiber.

Detailed Description

The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative work belong to the protection scope of the present invention.

According to fig. 1, the embodiment provides a low phase noise optoelectronic oscillator, which includes a phase modulator 1, a polarization beam splitter 2, a first optical amplifier 3, a second optical amplifier 4, a double-balanced photodetector 5, and a laser 6, where the phase modulator 1 is connected to the laser 6 and the polarization beam splitter 2 through a first polarization controller 7 and a second polarization controller 8, respectively, the laser 6 outputs a dc optical signal and enters the phase modulator 1 through the first polarization controller 7, the optical signal modulated by the phase modulator 1 enters the polarization beam splitter 2 through the second polarization controller 8, the second polarization controller 8 is adjusted to make the optical signal enter the polarization beam splitter 2 at an angle of 45 degrees, the phase signal is converted into two paths of intensity signals with equal power, the first optical amplifier 3 and the second optical amplifier 4 are connected to the double-balanced photodetector 5, one path of intensity signal enters a port of a double-balanced photoelectric detector 5 through an optical fiber, a tunable optical extension line 9 and a second optical amplifier 4, the other path of intensity signal enters the port of the double-balanced photoelectric detector 5 through the optical fiber, a tunable optical attenuator 10 and a first optical amplifier 3 and is converted into an electric signal, the electric signal is fed back through a microwave amplifier 11, a band-pass filter 12 and an electric coupler 13, and the fed-back electric signal drives a phase modulator 1 to form a closed-loop oscillation circuit.

The optical fibers comprise a first optical fiber 14 and a second optical fiber 15, and the polarization beam splitter 2 is respectively connected with the tunable optical extension line 9 and the adjustable optical attenuator 10 through the first optical fiber 14 and the second optical fiber 15. The phase modulator 1 is a lithium niobate phase modulator. The first optical amplifier 3 and the second optical amplifier 4 are both semiconductor optical amplifiers. The second optical fiber 15 is connected to the first optical amplifier 3 through the variable optical attenuator 10.

The laser 6 outputs a direct current optical signal which enters the phase modulator 1 through the first polarization controller 7, the optical signal modulated by the phase modulator 1 enters the polarization beam splitter 2 through the second polarization controller 8, the second polarization controller 8 is adjusted to enable the optical signal to enter the polarization beam splitter 2 at an angle of 45 degrees, therefore, phase signals are converted into two paths of intensity signals with equal power, one path of intensity signal passes through the first optical fiber 14 and the tunable optical extension line 9, the second optical amplifier 4 enters the port of the double-balanced photoelectric detector 5, the other path of intensity signal passes through the second optical fiber 15, the adjustable optical attenuator 10 and the first optical amplifier 3 and enters the port of the double-balanced photoelectric detector 5, the intensity signal is converted into an electric signal by the double-balanced photoelectric detector 5, the electric signal is fed back through the microwave amplifier 11, the band-pass filter 12 and the electric coupler 13, and the fed-back electric signal drives the phase modulator 1 to form a closed-loop oscillation circuit.

The photoelectric oscillator of the structure of the utility model can start oscillation only if the signal of the mode determined by the internal first loop and the mode determined by the second loop are simultaneously satisfied, other modes are well inhibited, single longitudinal mode output can be obtained, the cavity length of the first loop and the second loop is matched through the tunable light extension line 9, the oscillation starting mode required in the bandwidth of the band-pass filter 12 can be selected, the loss of the whole loop is reduced through the use of the phase modulator 1, the Q value of the loop is increased, the output of high-quality signals is ensured, the optical power of the first loop and the second loop can be ensured to be equal through adjusting the tunable optical attenuator 10, not only the side mode can be better inhibited, the loop common mode noise including the relative intensity noise of the laser 6 can be inhibited through combining the double-balanced photoelectric detector 5, the signal quality of output signals is ensured, the power fluctuation of the signal entering the double balanced photodetector 5 can be further suppressed by adjusting the operating currents of the first optical amplifier 3 and the second optical amplifier 4 to ensure the output of a high quality signal.

The foregoing illustrates and describes the principles, general features, and advantages of the present invention. It will be understood by those skilled in the art that the present invention is not limited to the above embodiments, and that the foregoing embodiments and descriptions are provided only to illustrate the principles of the present invention without departing from the spirit and scope of the present invention. The scope of the invention is defined by the appended claims and equivalents thereof.

Claims

1. A low phase noise optoelectronic oscillator, comprising: the phase modulator (1) is respectively connected with the laser (6) and the polarization beam splitter (2) through a first polarization controller (7) and a second polarization controller (8), the laser (6) outputs direct current optical signals to enter the phase modulator (1) through the first polarization controller (7), the optical signals modulated by the phase modulator (1) enter the polarization beam splitter (2) through the second polarization controller (8), the second polarization controller (8) is adjusted to enable the optical signals to enter the polarization beam splitter (2) at an angle of 45 degrees, the phase signals are converted into two paths of intensity signals with equal power, the first optical amplifier (3) and the second optical amplifier (4) are connected with the double-balanced photoelectric detector (5), one path of intensity signal enters a port of a double-balanced photoelectric detector (5) through an optical fiber, a tunable optical extension line (9) and a second optical amplifier (4), the other path of intensity signal enters the port of the double-balanced photoelectric detector (5) through the optical fiber, a tunable optical attenuator (10) and a first optical amplifier (3) to be converted into an electric signal, the electric signal is fed back through a microwave amplifier (11), a band-pass filter (12) and an electric coupler (13), and the fed-back electric signal drives a phase modulator (1) to form a closed-loop oscillation circuit.

2. A low phase noise optoelectronic oscillator according to claim 1, wherein: the optical fiber comprises a first optical fiber (14) and a second optical fiber (15), and the polarization beam splitter (2) is respectively connected with the tunable light extension line (9) and the adjustable optical attenuator (10) through the first optical fiber (14) and the second optical fiber (15).

3. A low phase noise optoelectronic oscillator according to claim 1, wherein: the phase modulator (1) is a lithium niobate phase modulator.

4. A low phase noise optoelectronic oscillator according to claim 1, wherein: the first optical amplifier (3) and the second optical amplifier (4) are both semiconductor optical amplifiers.

5. A low phase noise optoelectronic oscillator according to claim 2, wherein: the second optical fiber (15) is connected with the first optical amplifier (3) through an adjustable optical attenuator (10).