Frequency-locking and threshold current-lowering effects of a quantum cascade laser and an application in gas detection field<xref ref-type="fn" rid="cpb141381fn1">*</xref>

Frequency-locking and threshold current-lowering effects of a quantum cascade laser and an application in gas detection field*

Chen Wei-Gen, Wan Fu†, Zou Jing-Xin, Gu Zhao-Liang, Zhou Qu

(a) Even and odd modes in vacuum. (b) Threshold current-lowering effect of optical feedback on QCL.