Tunable optical frequency converter based on a phase modulator

Patent metadata

Field	Value
Publication number	US-9235105-B2
Application number	US-201214360516-A
Country	US
Kind code	B2
Filing date	Oct 24, 2012
Priority date	Nov 23, 2011
Publication date	Jan 12, 2016
Grant date	Jan 12, 2016

Abstract

The present invention provides a tunable optical frequency converter based on a phase modulator, which comprises a laser, a first optical isolator and a circulating frequency shift module. Said circulating frequency shift module is composed of an optical coupler, a phase modulator, an optical amplifier, a second optical isolator, a first optical circulator, an optical fiber Bragg grating, a second optical circulator, a tunable filter and a tunable attenuator. Light outputted by said laser is inputted to said circulating frequency shift module to conduct frequency converting repeatedly after passing through the first optical isolator, and then separated by a tunable filter and a second optical circulator, then the frequency converted light is outputted from the port of the circulating frequency shift module. The frequency converter provided in the present invention has a compact volume and fewer optical components, which means it is easy to be integrated, a big frequency converting range, a high frequency converting efficiency and a high output power.

First claim

What is claimed is:

1. A tunable optical frequency converter based on a phase modulator, comprising:
a laser ( 1 ), a first optical isolator ( 2 ), and a circulating frequency shift module ( 3 ) based on the phase modulator, wherein
light output by the laser ( 1 ) is input to the circulating frequency shift module ( 3 ) to conduct frequency converting repeatedly after passing through the first optical isolator ( 2 ), separated by a tunable filter ( 38 ) and a second optical circulator ( 37 ) of the circulating frequency shift module ( 3 ), and frequency converted light is output from a port ( 4 ) of the circulating frequency shift module ( 3 ).

2. The tunable optical frequency converter according to claim 1 , wherein the laser ( 1 ) is a semiconductor laser, a gas laser, a solid laser, or a fiber laser with an operating wavelength in the 100 nm-100,000 nm band.

3. The tunable optical frequency converter according to claim 1 , wherein an optimum value of a closed-loop gain coefficient of the circulating frequency shift module ( 3 ) is 1.

4. The tunable optical frequency converter according to claim 1 , wherein the circulating frequency shift module ( 3 ) further comprises an optical coupler ( 31 ), a phase modulator ( 32 ), an optical amplifier ( 33 ), a second optical isolator ( 34 ), a first optical circulator ( 35 ), an optical fiber Bragg grating ( 36 ), and a tunable attenuator ( 39 ).

5. The tunable optical frequency converter according to claim 4 , wherein the phase modulator ( 32 ) includes a phase modulator and a frequency modulator.

6. The tunable optical frequency converter according to claim 4 , wherein a total power of two combined light beams of the optical coupler ( 31 ) cannot exceed a maximum allowable light power of the phase modulator ( 32 ).

7. The tunable optical frequency converter according to claim 4 , wherein the first optical circulator ( 35 ) is a 3-port circulator, wherein, a first port is connected to an output port of the second optical isolator ( 34 ), a second port is connected to an input port of the optical fiber Bragg grating ( 36 ), and a third port is connected to an absorbing load which absorbs reflected light from the optical fiber Bragg grating ( 36 ).

8. The tunable optical frequency converter according to claim 4 , wherein the second optical circulator ( 37 ) is a 3-port circulator, wherein, a first port thereof is connected to an output port of the optical fiber Bragg grating ( 36 ), a second port is connected to an input port of the tunable filter ( 38 ), and a third port serves as the port ( 4 ) of the circulating frequency shift module ( 3 ).

9. The tunable optical frequency converter according to claim 4 , wherein an operating frequency bandwidth of respective members in the circulating frequency shift module ( 3 ) converting the frequency based on the phase modulator is not less than a frequency difference between a maximum output frequency of the port ( 4 ) of the circulating frequency shift module ( 3 ) and that of the laser ( 1 ).

10. The tunable optical frequency converter according to claim 4 , wherein the operating wavelength bands of the first optical isolator ( 2 ) and respective members in the circulating frequency shift module ( 3 ) are consistent with that of the laser ( 1 ).

11. The tunable optical frequency converter according to claim 4 , wherein the tunable filter ( 38 ) is a narrow-band filter which reflects a narrow-band light desired to be filtered to the port ( 4 ) of the second optical circulator ( 37 ) so as to output it, and transmits the light with other frequencies to an input port of the tunable attenuator ( 39 ), a frequency variation of the frequency converter is equal to a difference between a frequency of the narrow-band output light of the tunable filter ( 38 ) and that of an output light of the laser ( 1 ), and a tunable frequency range of the frequency converter is not more than that of the narrow-band output light of the tunable filter ( 38 ).

12. The tunable optical frequency converter according to claim 11 , wherein the tunable filter ( 38 ) is a frequency-tunable filter manufactured by one-dimensional defect-photonic-crystal technology or optical-diffraction-grating technology.

13. The tunable optical frequency converter according to claim 12 , wherein a photonic bandgap of a one-dimensional photonic crystal is not less than a frequency tuning range of a final output light wave of the tunable optical frequency converter, the one-dimensional photonic crystal includes a refractive index adjustable defect layer, a refractive index adjusting method of which includes electro-induced refractive index change, magneto-induced refractive index change, acoustic-induced refractive index change, photo-induced refractive index change, force-induced refractive index change, or thermal-induced refractive index change, the one-dimensional photonic crystal has a defect mode which changes along with a change of the refractive index of the defect layer.

14. The tunable optical frequency converter according to claim 1 , wherein a closed-loop gain coefficient of the circulating frequency shift module ( 3 ) is a positive integer other than 1.

15. The tunable optical frequency converter according to claim 1 , wherein a closed-loop gain coefficient of the circulating frequency shift module ( 3 ) is a reciprocal value of a positive integer other than 1.

Assignees

• Univ Shenzhen

Inventors

• Ouyang Zhengbiao
• Qi Chunchao

Classifications

• G02F2203/055

  wavelength filtering · CPC title

• G02F2201/17

  Multi-pass arrangements, i.e. arrangements to pass light a plurality of times through the same element, e.g. by using an enhancement cavity · CPC title

• H01S3/06791

  Fibre ring lasers (fibre laser gyrometers G01C19/72) · CPC title

• G02F2201/307

  Reflective grating, i.e. Bragg grating · CPC title

• H01S3/1003

  tunable optical elements, e.g. acousto-optic filters, tunable gratings · CPC title