Single-mode InGaAs submonolayer quantum dot photonic crystal VCSELs

Abstract

An InGaAs submonolayer (SML) quantum dot photonic crystal vertical-cavity surface-emitting laser (QD PhC-VCSEL) for fibre-optic applications is demonstrated for the first time. The active region of the device contains three InGaAs SML QD layers. Each of the InGaAs SML QD layers is formed by alternate deposition of InAs (<1 ML) and GaAs. Single-fundamental-mode CW output power of 3.8 mW at 28 mA has been achieved in the 990 nm range, with a threshold current of 0.9 mA. A side-mode suppression ratio (SMSR) larger than 35 dB has been observed over the entire current operating range.

VCSEL structures used to suppress higher-order transverse modes

“…Currently, PC VCSELs suffer from relatively high electrical (see Table 1) and thermal resistances and very low efficiency (see values of the slope efficiency given in Table 1). The highest RT SFM output obtained in PC VCSELs equals 3.8 mW in the 10−μm device [58] emitting the 996−nm radiation and its lower RT threshold current was equal to only 0.9 mA (1.15 kA/cm 2 ). PC VCSELs are very promising devices potentially offering relatively high SFM outputs, but their development has just been started, so they need more time necessary for their modelling and structure optimization [62][63][64] to reach an essential improvement.…”

“…This fact is used in photonic−crystal (PC) VCSELs, in which the unaffected central VCSEL region (being the line crystal defect) is sur− rounded by the photonic crystal composed of a few periods of air columns etched parallel to the VCSEL axis [ Fig. 5(d)] [56][57][58][59][60] (lines 26-28, 35, and 43). The photonic crystal works here as an effective index radial cladding.…”

High Power and Single Mode Lasing Characteristics in Vertical Cavity Surface Emitting Laser by Varying Photonic Bandgap Structures

“…반면에 광 결정을 이용한 수직공진 표면발광 레이저는 기 존의 기술을 이용하여 홀을 식각함으로써 손쉽게 단일모드 로 구동하는 수직공진 표면발광 레이저를 구현할 수 있기 때 문에 광 결정에 대한 연구가 활발하게 진행되고 있다. [8,9,10] 일반적인 산화 수직공진 표면발광 레이저에서는 산화구경 의 크기를 3 μm이하로 작게 할 경우 단일모드를 구현할 수 있지만, 일단 산화구경을 작게 조절하는 것이 어렵고, 저항 이 증가한다. 또한 변조 대역폭에 한계가 있으며, 속도가 감 소하고 소자수명에도 영향을 미치게 되어 통신용 광소자로 서는 부적합하다.…”