Fabrication and modulation characteristics of InGaAsP/InGaAsP MQW DCPBH lasers at λ ～ 1.57 μm

摘要

InGaAsP/InGaAsP multiple-quantum-well (MQW) double-channel planar-buried heterostructure (DCPBH) lasers emitting at λ ～ 1.57 μm were fabricated by optimizing the epitaxial growth with material characterization. At 25 ℃ (85 ℃), a 1.8-μm-wide and 300-μm-long antireflectivity/high reflectivity coated laser exhibits a threshold current of 8 mA (23 mA) and a slope efficiency of 0.34 mW/mA (0.24 mW/mA) in continuous-wave mode (cw) as a result of the optimized thickness of the p-InP filling layer in the PBH structure with p-n-p-n current blocking layers. The maximum cw output power was approximately 20 MW at 25 ℃, which was reduced to 17 mW at 85 ℃. The peak wavelength varied from 1572 nm at 25 ℃ to 1602 nm at 100 ℃ for a fixed output power of 5 mW, indicating a temperature coefficient of ～ 0.4 nm/K. The resonance frequency in the small-signal modulation response of devices depends on the etching depth of the U-shaped double channel; it increases from 0.4 GHz without channel etching to 4.3 GHz with 7-μm-thick etching. The full-width at half maximum values in the horizontal and vertical far-field patterns were approximately 24.5° (25.2°) and 29.4° (30.1°), respectively, at 25 ℃ (85 ℃).