Parity-time symmetric gratings in 1550  nm distributed-feedback laser diodes: insight on device design rules

Abstract

We build up on former results from our work on parity-time symmetric gratings implemented in 1550 nm distributed feedback laser diodes to address the design issues raised by the first observed trends. These laser diodes are of "complex-coupled" nature, with modulations of both real and imaginary part of effective index, with relative phase π related to the parity-time symmetry. The unidirectionality of the photonic behavior in reflection mode is dependent on the level of extra losses incurred by the metallic grating used to implement fixed loss modulation onto a nearly uniform gain, either as a first order or as a third order grating. The observed behavior suggests that facets play a large role in setting the desired "unidirectional" lasing operation points, with preferential emission on one side. We explore this issue, of generic interest for the coupling of parity-time symmetric structures to open space.

Superluminality in parity-time symmetric Bragg gratings

“…Numerous important review articles [8-12, 60, 61] have explained the state-of-the-art experimental advancements in  symmetry within photonic lattices, photonic crystals, and metasurfaces/ metamaterials. We also note that Benisty et al have recently provided insights into device design rules for  -symmetric gratings operating at 1550nm [62]. For more detailed information about the advancement of PTBGs in experiments, we refer readers to this literature [62] and the references therein.…”

“…We also note that Benisty et al have recently provided insights into device design rules for  -symmetric gratings operating at 1550nm [62]. For more detailed information about the advancement of PTBGs in experiments, we refer readers to this literature [62] and the references therein.…”

Advances in Semiconductor Lasers Based on Parity–Time Symmetry

“…After reaching the threshold for the PT symmetry current, mode degeneracy and doubling of the mode spacing were observed. In 2021, de la Perrière et al of the Center for Nanosciences and Nanotechnologies in France [45,57] experimentally realized a DFB laser based on PT-symmetric dual gratings, with a central wavelength of 1550 nm. The laser structure used lateral ripple gratings to modulate the real part of the refractive index and deposited lateral metal stripes to modulate the imaginary part of the refractive index, as shown in Figure 4.…”