Dynamical Characteristics of External Cavity Quantum Cascade Lasers

Hamadou Abdelouahab

doi:10.35840/2631-5092/4520

Abstract

In this paper, we calculate the dynamical characteristics such as delay time, rise time, and time to steady state establishment, of a mid infrared quantum cascade laser coupled to external cavity. The approach is based on the three-level rate equations including the dependence of the loss on external cavity parameters. We find in particular that the threshold current of external cavity is strongly influenced by the external reflectivity and external cavity length. In addition, the equations that allow for the determination of the dynamical characteristics are derived within the premises of our model in the general case. The effects of the external cavity parameters on dynamical characteristics are also explored.

Highlights

After the first demonstration of the quantum cascade (QC) laser by Faist in 1994 [1], external cavity (EC) QC laser was demonstrated for the first time by Luo in 2001 [2]
It is well known that EC strongly affects the losses, photon lifetime and threshold current of QC laser, and influence the turn on delay time where it decreases with increasing external reflectivity [10,11,14,15]
6b, and Figure 6c, where we show the variation of the delay time tdEC, (b) rise time ∆trEisCe, and (c) to steady state establishment (TSSE)

Summary

Introduction

After the first demonstration of the quantum cascade (QC) laser by Faist in 1994 [1], external cavity (EC) QC laser was demonstrated for the first time by Luo in 2001 [2]. 2, τ3 is the lifetime of the upper level and defined as τ3 = 1 / (1 / τ32 +1 / τ31) , τout is the electron escape time between two adjacent stages [16], β defines the fraction of the spontaneous emission light emitted in the lasing mode [17], N p is the number of stages, ρcav = 1+ Lext / (neff L) is the ratio of optical path lengths of the FP and the external cavity [18] where neff is the effective refractive index of FP active region, and GEC and GEC are the gain coefficients per period in the FP and in the external cavity respectively The latter is defined through [14]. With the help of Eq(9) we get after easy algebra for the following expression e

FP th pG

Findings

Conclusion