Lowering the lasing threshold of distributed feedback lasers with loss

TL;DR

This paper demonstrates that in 1D distributed feedback lasers, increasing loss in absorbing layers can induce lasing at frequencies shifted towards the medium's transition frequency, thereby lowering the lasing threshold.

Contribution

It reveals a novel loss-induced lasing mechanism in DFB lasers, showing how loss can be used to control and reduce the lasing threshold.

Findings

Loss-induced lasing occurs when lasing frequency differs from medium's transition frequency.

Broadening of the resonator mode with increasing loss enhances cavity-medium interaction.

Lasing threshold is lowered due to mode broadening and frequency shift towards the transition frequency.

Abstract

We study laser generation in 1D distributed feedback lasers with amplifying and lossy layers. We show that when the lasing frequency differs from the transition frequencies of the amplifying medium, loss induced lasing may occur due to the broadening of the resonator mode with increasing loss in the absorbing layers. This broadening leads to a shift in the lasing frequency towards the transition frequency. As a result, the cavity mode interaction with the amplifying medium is enhanced, and the lasing threshold is lowered.