Cunda Wang

Competitive behavior of photons contributing to junction voltage jump in narrow band-gap semiconductor multi-quantum-well laser diodes at lasing threshold

The junction behavior of different narrow band-gap multi-quantum-well (MQW) laser diodes (LDs) confirmed that the jump in the junction voltage in the threshold region is a general characteristic of narrow band-gap LDs. The relative change in the 1310 nm LD is the most obvious. To analyze this sudden voltage change, the threshold region is divided into three stages by Ithl and Ithu, as shown in Fig. 2; Ithl is the conventional threshold, and as long as the current is higher than this threshold, lasing exists and the IdV/dI-I plot drops suddenly; Ithu is the steady lasing point, at which the separation of the quasi-Fermi levels of electron and holes across the active region (Vj) is suddenly pinned. Based on the evolutionary model of dissipative structure theory, the rate equations of the photons in a single-mode LD were deduced in detail at Ithl and Ithu. The results proved that the observed behavior of stimulated emission suddenly substituting for spontaneous emission, in a manner similar to biological evo...

Operational characteristics of a LD-pumped novel Yb,Y:CaF2 mode-locked laser using a SESAM

A LD-pumped novel Yb,Y:CaF2 femtosecond laser is demonstrated for the first time. The continuous-wave and mode-locked operational characteristics of the co-doped fluoride crystal are described in detail. With intracavity dispersion management using a prism-pair, a 330 fs pulse at a centre wavelength of 1049 nm is obtained. The average output power is 224 mW at a repetition rate of ~83 MHz.