Directly-coupled well-wire hybrid quantum confinement lasers with the enhanced high temperature performance

Abstract

It is well known that the laser diode performance will inevitably deteriorate when the device is heated. It has been a difficult issue to solve to date. In this letter, we are reporting a new solution to improve high-temperature performance of the laser diodes. The device uses a kind of directly-coupled well-wire hybrid quantum confinement (HQC) structure of the active medium based on the InGaAs-GaAs-GaAsP material system. This special HQC structure is constructed based on the strain-driven indium (In)-segregation effect and the growth orientation-dependent on-GaAs multi-atomic step effect. The measurement and analysis for the HQC laser sample show that the carrier leakage loss, the Auger recombination and gain-peak shifting due to heating are reduced in the HQC structure. It therefore increases the optical gain for lasing at high temperature. The power conversion efficiency is enhanced by > 57% and the threshold carrier density drops by > 24% at T ≥ 360 K, in comparison to the traditional quantum-well laser performance. A higher characteristic temperature of 240 K is obtained as well. It implies the better thermal stability of the HQC laser structure. These achievements show a significant prospect for developing high thermo-optic performance of laser diodes.

Ultra-broadband depolarization based on directly-coupled quantum wire-to-well modulation and their aliasing effect for polarization-insensitive light-emitting diodes

“…Previous research on this hybrid quantum-confined nanostructure focused mainly on its gain-broadening (super-gain) property due to the joint role of well and wires, 32 as well as the improvement in the high-temperature performance of the device due to the reduction in non-radiative recombination under the action of quantum wires. 33 Recently, a distinguished depolarization property due to wire-to-well strain modulation in this well–wire-hybrid nanostructure was observed in our experiments for the first time. This depolarization effect is associated with an interesting quantum well–wire interaction mechanism, which is different from traditional ones and has not been reported in any previous literature.…”

“…This is achieved by utilizing the orientation-dependent on-GaAs multi-atomic step effect in the material growth. 32–34 A high In-content of 0.17 is applied for the InGaAs active structure (including the well and wires), ensuring that the strain-driven In-segregation effect would occur and promoting In-atom migration under the In-segregation effect during the material growth. 35,36 Owing to the In-segregation effect, the In-contents in both well and wires would vary continuously along the growth direction, resulting in the band-gap of the active structure changing accordingly.…”

“…All the above structural characterization data are consistent with our previous research results. 32,33…”

“…In view of the above considerations, we are proposing a novel depolarization solution and the corresponding quantum structure to realize ultra-broadband depolarization for strained light-emitting diodes. It is based on a kind of quantum well–wire-hybrid nanostructure recently proposed by our group, 32,33 where the quantum wires are formed directly on the well in a self-assembling way. This hybrid quantum-confined structure has displayed some special advantages over traditional quantum wells or dots.…”

Removing Thermal Gain–Cavity Detuning Effect Based on Supergain Quantum Well–Wire Hybrid Nanostructures for Single-Frequency Laser Diodes

“…It is based on the fundamental change of a traditional gain distribution to a supergain spectrum by utilizing a complex self-assembled quantum well–wire hybrid (WWH) nanostructure with an InGaAs material system. The WWH nanostructure is a kind of newly reported and investigated hybrid quantum structure and has displayed the possibilities of realizing a supergain spectrum and reducing thermal carrier loss for the improvement of thermal performance of laser diodes from the recent research. , This previous research and results on the WWH nanostructure and its properties have inspired us to discover a new mechanism and approach to solve the thermal gain–cavity detuning problem for single-frequency laser diodes by means of the supergain spectrum that may be formed in the WWH nanostructure. To the best of our knowledge, no literature has reported the investigation of removing the thermal gain–cavity detuning effect with a hybrid quantum nanostructure for single-frequency laser diodes so far.…”