1.3 μm p-Modulation Doped InGaAs/GaAs Quantum Dot Lasers with High Speed Direct Modulation Rate and Strong Optical Feedback Resistance

Xia-Yida Maxueer,Zhong-Kai Zhang,Dan Lu,Yi-Ming He,Xiao-Guang Yang,Tao Yang,Hong-Yu Chai,Zun-Ren Lv

doi:10.3390/cryst10110980

Abstract

Aiming to realize high-speed optical transmitters for isolator-free telecommunication systems, 1.3 μm p-modulation doped InGaAs/GaAs quantum dot (QD) lasers with a 400 μm long cavity have been reported. Compared with the un-doped QD laser as a reference, the p-doped QD laser emits at ground state, with an ultra-low threshold current and a high maximum output power. The p-doped QD laser also shows enhanced dynamic characteristics, with a 10 Gb/s large-signal direct modulation rate and a 7.8 GHz 3dB-bandwidth. In addition, the p-doped QD laser exhibits a strong coherent optical feedback resistance, which might be beyond −9 dB.

Highlights

In telecommunication systems based on traditional quantum well (QW) lasers, optical isolators are indispensable devices
Under the bias current of 65 mA, the p-doped device emits at a wavelength of 1315 nm, which is under the ground state [17]
The addition of p-doping in the active region of quantum dot (QD) could increase the probability of holes occupying the ground state of the valence band, increasing the ground state energy level mode gain

Summary

Introduction

In telecommunication systems based on traditional quantum well (QW) lasers, optical isolators are indispensable devices. Quantum dot (QD) lasers have been suggested as an alternative to QW devices to realize low-cost and isolator-free applications. Due to the behavior of three-dimensional carrier confinement, QD lasers show a stronger damping effect and a lower linewidth enhancement factor (α-factor), which contribute to the resistance of undesired optical feedback [4,5,6,7]. A representative work has reported on a 25 Gb/s error-free transmission with an integrated InGaAs/GaAs QD laser transmitter based on Si substrate without optical isolators for core input/output (I/O) applications [8]. QD lasers have exhibited many superior properties, such as ultra-low threshold current density [9,10,11], high temperature stability and high working temperature [12,13]

Methods

Results

Conclusion