Spectral dynamics of picosecond gain-switched pulses from nitride-based vertical-cavity surface-emitting lasers.
Short pulses generated from low-cost semiconductor lasers by a simple gain-switching technique have attracted enormous attention because of their potential usage in wide applications. Therein, reducing the durations of gain-switched pulses is a key technical point for promoting their applications. Therefore, understanding the dynamic characteristics of gain-switched pulses is highly desirable. Herein, we used streak camera to investigate the time- and spectral-resolved lasing characteristics of gain-switched pulses from optically pumped InGaN single-mode vertical-cavity surface-emitting lasers. We found that fast initial components with ultra-short durations far below our temporal resolution of 5.5 ps emerged on short-wavelength sides, while the entire pulses were down-chirped, resulting in the simultaneous broadening of the spectrum and pulse width. The measured chirp characteristics were quantitatively explained using a single-mode rate-equation model, combined with carrier-density-dependent gain and index models. The observed universal fast short-wavelength components can be useful in generating even shorter pulses from gain-switched semiconductor lasers.
Institute for Solid State Physics, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581, Japan.
Shaoqiang
S
Chen
Institute for Solid State Physics, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581, Japan.
Takashi
T
Ito
Institute for Solid State Physics, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581, Japan.
Akifumi
A
Asahara
Institute for Solid State Physics, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581, Japan.
Masahiro
M
Yoshita
Department of Physics & Department of Electronic Engineering, Xiamen University, Xiamen 361005, Fujian, China.
Wenjie
W
Liu
Department of Physics & Department of Electronic Engineering, Xiamen University, Xiamen 361005, Fujian, China.
Jiangyong
J
Zhang
Department of Physics & Department of Electronic Engineering, Xiamen University, Xiamen 361005, Fujian, China.
Baoping
B
Zhang
Institute for Solid State Physics, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581, Japan.
Tohru
T
Suemoto
Institute for Solid State Physics, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581, Japan.
Hidefumi
H
Akiyama