METHODS AND APPARATUS FOR POWER-EQUALIZED OPTICAL FREQUENCY COMB GENERATION

• US 20140178020A1
• Filed: 05/03/2013
• Published: 06/26/2014
• Est. Priority Date: 09/13/2012
• Status: Active Grant

• Current Assignee: Roshmere, Inc.
• Original Assignee: Ram Photonics, Llc
• Inventors: Kuo, Ping Piu, Myslivets, Yauheni
• Granted Patent: US 9,513,423 B2
• Time in Patent Office: Days
• US Class Current: 385/122
• CPC Class Codes: G02B 6/00 Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
• CPC Class Codes: G02B 6/02247 Dispersion varying along the longitudinal direction, e.g. dispersion managed fibre
• CPC Class Codes: G02F 1/353 Frequency conversion, i.e. wherein a light beam is generated with frequency components different from those of the incident light beams
• CPC Class Codes: G02F 1/383 of the optical fibre type
• CPC Class Codes: G02F 1/39 for parametric generation or amplification of light, infrared or ultraviolet waves
• CPC Class Codes: G02F 2201/16 series; tandem
• CPC Class Codes: G02F 2203/26 Pulse shaping; Apparatus or methods therefor
• CPC Class Codes: G02F 2203/56 Frequency comb synthesizer

Abstract

An optical device for generating a frequency comb includes an optical source and a first waveguide comprising a nonlinear optical medium operable to mix at least two input optical waves to generate a plurality of first optical waves. The optical device also includes a second waveguide concatenated to the first waveguide and characterized by a first dispersion characteristics and operable to compress the waveforms of the plurality of first optical waves and to reduce a frequency chirp introduced by the first waveguide. The optical device additionally includes a third waveguide concatenated to the second waveguide. The third waveguide comprises a nonlinear optical medium and is operable to mix the plurality of first optical waves to generate a plurality of second optical waves and to increase a total number of second optical waves with respect to a total number of first optical waves.

Claims

1. An optical device for generating a frequency comb, the optical device comprising:

an optical source operable to provide at least two input optical waves characterized by a first input frequency and a second input frequency, respectively, wherein the first input frequency and the second input frequency are separated by a frequency spacing;

a first waveguide comprising a nonlinear optical medium characterized by a nonlinear optical response and operable to mix the at least two input optical waves to generate a plurality of first optical waves characterized by respective first frequencies separated from each other by the frequency spacing; and

a second waveguide concatenated to the first waveguide, wherein the second waveguide is characterized by a first dispersion characteristics such that the second waveguide is operable to compress the waveforms of the plurality of first optical waves.

2. The optical device of claim 1 wherein the plurality of first optical waves is characterized by a frequency chirp, and the second waveguide is operable to reduce the frequency chirp.

3. The optical device of claim 1 wherein the second waveguide is characterized by a chromatic dispersion parameter D.

4. The optical device of claim 3 wherein the chromatic dispersion parameter D has a value such that the second waveguide is operable to reduce a phase modulation introduced by the first waveguide.

5. The optical device of claim 1 comprising a third waveguide concatenated to the second waveguide, wherein the third waveguide comprises a nonlinear optical medium and is operable to mix the plurality of first optical waves to generate a plurality of second optical waves characterized by respective second frequencies separated from each other by the frequency spacing.

6. The optical device of claim 5 wherein the third waveguide is characterized by a second dispersion characteristics such that the third waveguide is operable to increase a total number of second optical waves with respect to a total number of first optical waves.

7. The optical device of claim 5 wherein the third waveguide is characterized by a dispersion slope that is not greater than about 10 ps/km-nm² within a spectral bandwidth of the plurality of second optical waves.

8. The optical device of claim 5 wherein the third waveguide is characterized by a unit-length chromatic dispersion that is not greater than about 2000 ps/km-nm within a spectral span of the frequency comb.

9. The optical device of claim 5 wherein each of the first waveguide and the third waveguide is characterized by a unit-length dispersion that is not greater than about 2000 ps/km-nm within a spectral bandwidth of the plurality of first optical waves and a spectral bandwidth of the plurality of second optical waves, respectively.

10. The optical device of claim 5 wherein each of the first waveguide and the third waveguide comprises an optical medium with a third-order nonlinear susceptibility greater than 1×

10<sup>−

23</sup> m²/V².

11. The optical device of claim 5 comprising a fourth waveguide concatenated to the third waveguide, wherein the fourth waveguide is characterized by a third dispersion characteristics such that the fourth waveguide is operable to reduce the frequency chirp in the plurality of second optical waves introduced by the third waveguide;

and

a fifth waveguide concatenated to the fourth waveguide, wherein the fifth waveguide comprises a nonlinear optical medium and is operable to mix the plurality of second optical waves to generate a plurality of third optical waves characterized by respective third frequencies separated from each other by the frequency spacing, and wherein the fifth waveguide is characterized by a fourth dispersion characteristics that increases a total number of third optical waves in comparison with the total number of second optical waves.

12. A method of generating a frequency comb comprising:

providing at least two input optical waves characterized by respective input frequencies separated from each other by a frequency spacing;

mixing, via a first waveguide, the at least two input optical waves to provide a plurality of first optical waves characterized by respective first frequencies separated from each other by the frequency spacing, wherein the first waveguide comprises a nonlinear optical medium; and

compressing, via a second waveguide concatenated to the first waveguide, the plurality of first optical waves to provide a plurality of first compressed optical waves.

13. The method of claim 12 wherein the first waveguide introduces a frequency chirp in the plurality of first optical waves, and the second waveguide is characterized by a first dispersion characteristics such that the second waveguide reduces the frequency chirp introduced by the first waveguide.

14. The method of claim 12 comprising mixing, via a third waveguide concatenated to the second waveguide, the plurality of first compressed optical waves to provide a plurality of second optical waves characterized by respective second frequencies separated from each other by the frequency spacing.

15. The method of claim 14 wherein the third waveguide is characterized by a second dispersion characteristics that increases a total number of second optical waves in comparison to a total number of first optical waves.

16. The method of claim 14 comprising:

compressing, via a fourth waveguide concatenated to the third waveguide, the plurality of second optical waves to provide a plurality of second compressed optical waves, wherein the fourth waveguide is characterized by a third dispersion characteristics such that the fourth waveguide reduces the frequency chirp introduced by the third waveguide; and

mixing, via a fifth waveguide concatenated to the fourth waveguide, the plurality of second compressed optical waves to provide a plurality of third optical waves characterized by respective third frequencies separated from each other by the frequency spacing, wherein the fifth waveguide is characterized by a fourth dispersion characteristics that maximizes a total number of third optical waves.

17. An optical device for generating a frequency comb, the optical device comprising:

an optical source operable to provide at least two input optical waves characterized by a first input frequency and a second input frequency, respectively, wherein the first input frequency and the second input frequency are separated by a frequency spacing; and

a first waveguide comprising a nonlinear optical medium characterized by a nonlinear optical response and operable to mix the at least two input optical waves to generate a plurality of first optical waves characterized by respective first frequencies separated from each other by the frequency spacing.

18. The optical device of claim 17 comprising a second waveguide concatenated to the first waveguide, wherein the second waveguide is characterized by a first dispersion characteristics such that the second waveguide is operable to compress the waveforms of the plurality of first optical waves.

19. The optical device of claim 18 comprising a third waveguide concatenated to the second waveguide, wherein the third waveguide comprises a nonlinear optical medium and is operable to mix the plurality of first optical waves to generate a plurality of second optical waves characterized by respective second frequencies separated from each other by the frequency spacing.

20. The optical device of claim 19 wherein:

the plurality of first optical waves is characterized by a frequency chirp;

the second waveguide is operable to reduce the frequency chirp introduced by the first waveguide; and

the third waveguide is characterized by a second dispersion characteristics such that the third waveguide is operable to increase a total number of second optical waves with respect to a total number of first optical waves.