Method for generating ultrashort femtosecond pulses in optical parametric oscillator pumped by long pulses

Patent metadata

Field	Value
Publication number	US-9366939-B2
Application number	US-201514846695-A
Country	US
Kind code	B2
Filing date	Sep 4, 2015
Priority date	Nov 6, 2014
Publication date	Jun 14, 2016
Grant date	Jun 14, 2016

Abstract

A method for generating ultrashort femtosecond pulses in the optical parametric oscillator pumped by long pulses, comprising governing dispersion and nonlinearity in the optical parametric oscillator, forming linearly-chirped long pulses with broad bandwidth in the optical parametric oscillator, compressing the linearly-chirped long pulses to femtosecond pulses by a second-order dispersion outside the optical parametric oscillator cavity. The ultrashort femtosecond pulse is generated in the OPO with long pulse pumping.

First claim

We claim:

1. A method for generating ultrashort femtosecond pulses, comprising:
selecting a desired signal wavelength,
setting self phase modulation elements in a cavity of an optical parametric oscillator to cause a third-order nonlinearity effect in the cavity of the optical parametric oscillator,
setting a net second-order dispersion in the cavity of the optical parametric oscillator and inserting a dispersive management element into the cavity of the optical parametric oscillator to guarantee that a sign of the intra-cavity net second-order dispersion is the same as a sign of the third-order nonlinearity, wherein the intra-cavity net dispersion is jointly provided by a nonlinear crystal and the dispersive management element,
setting a dispersion compensation device outside the cavity of the optical parametric oscillator to provide a dispersion with a sign being opposite to the sign of the intra-cavity net dispersion, determining the amount of the dispersion by an amount of signal chirp, dechirping signal pulses, and compressing the signal pulses to a femtosecond regime after dechirping, and
linearly chirping output idler pulses with a sign being opposite to the sign of the signal pulses, compensating for the second-order dispersion outside the cavity of the optical parametric oscillator, and compressing the idler pulses to the femtosecond regime.

2. The method for generating ultrashort femtosecond pulses according to claim 1 , wherein the third-order nonlinearity effect is caused by a nonlinear crystal of the optical parametric oscillator having a nonlinear refractive index of greater than an order of 10 −19 m 2 /W.

3. The method for generating ultrashort femtosecond pulses according to claim 2 , wherein when the third-order nonlinearity provided by the nonlinear crystal of the optical parametric oscillator is positive, and the sign of the intra-cavity net dispersion is positive; and when the third-order nonlinearity provided by the nonlinear crystal of the optical parametric oscillator is negative, the sign of the intra-cavity net dispersion is negative.

4. The method for generating ultrashort femtosecond pulses according to claim 1 , wherein the third-order nonlinearity effect is caused by a cascade nonlinearity in a nonlinear crystal where a phase-mismatched second-order optical parametric process of signal takes place.

5. The method for generating ultrashort femtosecond pulses according to claim 4 , wherein the sign of the intra-cavity net dispersion is determined by a sign of the cascade nonlinear phase shift, and
when the sign of the cascade nonlinear phase shift is positive, the sign of the intra-cavity net dispersion is positive, and when the sign of the cascade nonlinear phase shift is negative, the sign of the intra-cavity net dispersion is negative.

6. The method for generating ultrashort femtosecond pulses according to claim 1 , wherein the third-order nonlinearity effect is caused by inserting a third-order nonlinearity material into the cavity of the optical parametric oscillator to provide the third-order nonlinearity for broadening signal spectrum.

7. The method for generating ultrashort femtosecond pulses according to claim 6 , wherein when the third-order nonlinearity provided by the third-order nonlinearity material is positive, the sign of the intra-cavity net dispersion is positive; and when the third-order nonlinearity provided by the third-order nonlinearity material is negative, the sign of intra-cavity net dispersion is negative.

Assignees

• Univ Shanghai Jiaotong

Inventors

• Xie Guoqiang
• Qian Liejia
• Wang Fuyong
• Qin Zhipeng
• Yuan Peng

Classifications

• G02F2203/26

  Pulse shaping; Apparatus or methods therefor · CPC title

• G02F1/39 Primary

  for parametric generation or amplification of light, infrared or ultraviolet waves · CPC title

• G02F1/3551

  Crystals · CPC title

• G02F1/3532 Primary

  Arrangements of plural nonlinear devices for generating multi-colour light beams, e.g. arrangements of SHG, SFG, OPO devices for generating RGB light beams · CPC title

• G02F2001/392

  Physics · mapped topic