Shanghai Jiao Tong University

Chinese Academy of Sciences

Zhipeng Qin

Guoqiang Xie

Peng Yuan

Liejia Qian

Yi Zhou

Jianxin Chen

Zhen Qiao

Lingchen Kong

Fuyong Wang

A mid-infrared semiconductor saturable absorber mirror based on InAs/GaSb superlattice comprises a GaSb substrate with an anti-reflection film coated on the lower surface of the GaSb substrate; InAs/GaSb superlattice which has a specific structure and thickness and is arranged on the GaSb substrate; and Bragg reflection film which is arranged on the InAs/GaSb superlattice, wherein Bragg reflection film is composed of multiple pairs of ZnS and YbFfilm layers with a thickness of ¼ wavelength, and the YbFfilm layer is connected with the InAs/GaSb superlattice. The device not only has a mid-infrared working range with a broadband operation bandwidth, but also has the advantages of designable parameters, outstanding robustness, high damage threshold and the like, and sets a foundation for the development of mid-infrared ultrafast mode-locked lasers.

Mid-infrared semiconductor saturable absorber mirror based on INAS/GASB superlattice and preparation method thereof

A method for generating femtosecond vortex beams with high spatial intensity contrast, where a noncollinearly pumped HG beam femtosecond laser generates femtosecond HG beam and a cylindrical lens mode converter converts the femtosecond HG beam to femtosecond LG vortex beam. The HG beam femtosecond laser comprises a pump source, a gain medium, a saturable absorption mirror as mode-locker, and an output coupler with a noncollinear angle between the laser beam and the pump beam in the gain medium, which enables the laser to generate pure, order-tunable femtosecond HG beams. Femtosecond vortex beams obtained after the cylindrical lens converter have high-intensity-contrast, and are topological charge-tunable.

Method for generating femtosecond vortex beams with high spatial intensity contrast

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.

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

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Zhipeng Qin