Wavelength detuning of DFB laser incorporating compressively strained MQW and automatically buried absorptive grating

Abstract

The thermal effect on wavelength detuning of the uncooled packaged complex (loss)-coupled distributed feedback (DFB) edge emitting 1.55-mu m laser has been investigated for wide temperature range of -40 degrees C to 85 degrees C. The InGaAsP/InP laser diode incorporates a thin 1% compressively strained multiple quantum well (MQW) structure as well as an automatically buried InAsP buried layer in the grating region to simplify the steps of the epitaxial growth during the fabrication processes. As an experimental result, it has been found that the wavelength detuning between the gain medium (Fabry-Perot cavity) and the Bragg grating (for distributed feedback) should be optimized around -10 nm at the room temperature to accommodate their differently shifting center wavelengths for temperature changes where the gain profile changes faster than DFB wavelength for predicting a single mode operation in a wide temperature range. Based on the measured optical characteristics (threshold current, slope efficiency) of the fabricated diode laser, the characteristic temperature was estimated to be approximately 46 K and the slope efficiency ratio between room and high temperatures was around 70%. (C) 2011 Elsevier GmbH. All rights reserved.