Photonics based tunable multiband microwave filter

Patent metadata

Field	Value
Publication number	US-10547280-B2
Application number	US-201615557454-A
Country	US
Kind code	B2
Filing date	Mar 11, 2016
Priority date	Mar 12, 2015
Publication date	Jan 28, 2020
Grant date	Jan 28, 2020

Abstract

Various examples are provided for tunable radio frequency (RF) filtering. In one example, a RF multiband filter includes a Lyot filter including a tunable birefringence loop including a circulator and a polarization controller (PC) and a phase modulator (PM). The Lyot filter can generate an optical comb based at least in part upon a received optical signal and a polarization rotation angle of the polarization controller. The phase modulator (PM) can generate a modulated tap signal by modulating the optical comb by a RF input signal.

First claim

Therefore, at least the following is claimed:

1. A radio frequency (RF) filter, comprising:
a Lyot filter comprising a tunable birefringence loop comprising a length of polarization maintaining fiber (PMF), a circulator and a polarization controller (PC), the PC coupled to a distal end of the PMF through the circulator, where a received optical signal is provided to the PMF through a loop coupling circulator coupled to a proximal end of the PMF, the Lyot filter configured to generate an optical comb based at least in part upon the received optical signal and a polarization rotation angle of the PC; and
a phase modulator (PM) configured to generate a modulated tap signal by modulating the optical comb by a RF input signal.

2. The RF filter of claim 1 , wherein the circulator coupled via the PMF is the only circulator coupled to the loop coupling circulator.

3. The RF filter of claim 1 , wherein the PC is configured to adjust the polarization rotation angle in a range from 0° to 90°.

4. The RF filter of claim 1 , wherein the received optical signal is received by the loop coupling circulator through a first polarizer of the Lyot filter.

5. The RF filter of claim 4 , wherein the optical comb is provided to the PM through a second polarizer of the Lyot filter.

6. The RF filter of claim 5 , wherein the optical comb provided to the PM is amplified.

7. The RF filter of claim 1 , wherein the Lyot filter comprises a second tunable birefringence loop comprising a second circulator and a second PC, the second tunable birefringence loop coupled in series by a second loop coupling circulator.

8. The RF filter of claim 7 , wherein each tunable birefringence loop comprises single corresponding loop coupling circulator coupled to a single corresponding circulator via the corresponding PMF.

9. The RF filter of claim 7 , wherein the second tunable birefringence loop comprises a second PMF, the second PC coupled to a distal end of the second PMF via the second circulator.

10. The RF filter of claim 9 , wherein an output from the tunable birefringence loop is provided to a proximal end of the second PMF via the second loop coupling circulator.

11. The RF filter of claim 10 , wherein the output from the tunable birefringence loop is provided to the proximal end of the second PMF via a third PC.

12. The RF filter of claim 7 , wherein the received optical signal is received by the loop coupling circulator through a first polarizer of the Lyot filter.

13. The RF filter of claim 12 , wherein the optical comb is provided to the PM through a second polarizer after the second loop coupling circulator.

14. The RF filter of claim 7 , comprising a photo-detector (PD) configured to generate a RF output signal based upon the modulated tap signal.

15. The RF filter of claim 14 , wherein the RF output signal comprises six passbands or more.

16. The RF filter of claim 15 , wherein the RF output signal comprises ten passbands or more.

17. The RF filter of claim 14 , wherein passbands of the RF output signal comprise an even 3-dB bandwidth of 200 MHz and greater than 30 dB sidelobe suppression.

18. The RF filter of claim 14 , comprising a piece of dispersion compensating fiber (DCF) between the PM and the PD to provide a linear delay for wavelengths of the modulated tap signal.

19. The RF filter of claim 1 , wherein the received optical signal comprises a broadband optical signal filtered by a Gaussian optical filter.

20. The RF filter of claim 19 , wherein the Gaussian optical filter apodizes amplitudes of the modulated tap signal.

Assignees

• Univ Georgia

Inventors

• Fok Mable P
• Ge Jia

Classifications

• G02B6/274

  based on light guide birefringence, e.g. due to coupling between light guides (G02B6/105, G02B6/024 take precedence; mechanically induced birefringence G02F1/0134) · CPC title

• G02B6/29395

  configurable, e.g. tunable or reconfigurable (switching G02B6/35) · CPC title

• H03H2/003 Primary

  comprising optical fibre network elements (optical elements per se G02B, G02F; transmission systems using light waves H04B10/00) · CPC title

• G02B6/29389 Primary

  Bandpass filtering, e.g. 1x1 device rejecting or passing certain wavelengths (G02B6/2938 takes precedence) · CPC title

• H04B2210/006

  Devices for generating or processing an RF signal by optical means · CPC title