Purely Gain-Coupled Distributed-Feedback Bragg Semiconductor Laser Diode Emitting at 770 nm

Chunkao Ruan,Li Qin,Zaijin Li,Nan Zhang,Yongyi Chen,Peng Jia,Yuxin Lei,Zhijun Zhang,Yugang Zeng,Yue Song

doi:10.3390/app11041531

Abstract

The transition lines of Mg, K, Fe, Ni, and other atoms lie near 770 nm, therefore, this spectral region is important for helioseismology, solar atmospheric studies, the pumping of atomic clocks, and laser gyroscopes. However, there is little research on distributed-feedback (DFB) semiconductor lasing at 770 nm. In addition, the traditional DFB semiconductor laser requires secondary epitaxy or precision grating preparation technologies. In this study, we demonstrate an easily manufactured, gain-coupled DFB semiconductor laser emitting at 770 nm. Only micrometer scale periodic current injection windows were used, instead of nanoscale grating fabrication or secondary epitaxy. The periodically injected current assures the device maintains single longitudinal mode working in the unetched Fabry–Perot cavity under gain coupled mechanism. The maximum continuous-wave output power reached was 116.3 mW at 20 °C, the maximum side-mode-suppression ratio (SMSR) was 33.25 dB, and the 3 dB linewidth was 1.78 pm.

Highlights

Distributed feedback (DFB) semiconductor lasers, characterized by high power and efficiency [1,2], narrow linewidth [3,4], and tunable wavelength [5] have many applications in laser communication [6,7], in radar [8], and as a pumping source [9]
Semiconductor lasers emitting at 770 nm are not based on DFB, but on quantum dots [16], distributed Bragg reflector arrays [17], or vertical-external-cavity surface-emitting laser arrays [18]; DFB lasers emitting at 770 nm still remain more explored
We only use i-line-lithography technology to form a gain contrast in the active region [29,30] through surface periodic electrical injection, by modulating the imaginary part of the refractive index and obtaining a gain-coupled DFB semiconductor laser emitting at 770 nm that requires neither secondary epitaxy nor precision lithography

Summary

Introduction

Distributed feedback (DFB) semiconductor lasers, characterized by high power and efficiency [1,2], narrow linewidth [3,4], and tunable wavelength [5] have many applications in laser communication [6,7], in radar [8], and as a pumping source [9]. The portion of the spectrum near 770 nm, which contains the transition lines of Mg, K, Fe, Ni, and many other atoms [10], has many applications. It is used in helioseismology studies with resonance cells [11], the estimation of solar atmospheric parameters [12], and pumps for alkali-metal atomic clocks [13]. Semiconductor lasers emitting at 770 nm are not based on DFB, but on quantum dots [16], distributed Bragg reflector arrays [17], or vertical-external-cavity surface-emitting laser arrays [18]; DFB lasers emitting at 770 nm still remain more explored

Methods

Results

Conclusion