DFB lasers with ultrashort cavities or integrated passive waveguide reflectors are frequently proposed to realize directly modulated (DMLs) for carrying ultrahigh data rate signals. The former suffers from poor heatsink and laser cleavage yield, while the single-mode stability of latter scheme is seldom addressed. mode selection device performance a well known be very sensitive facet reflection...

In this work, quantum cascade lasers (QCLs) based on strain compensation combined with two-phonon resonance design are presented. Distributed feedback (DFB) laser emitting at ~ 4.76 μm was fabricated through a standard buried first-order grating and buried heterostructure (BH) processing. Stable single-mode emission is achieved under all injection currents and temperature conditions without any...

Abstract This study aimed to determine the relationship between L2 learners' autonomy and their cognitive style focusing on reflectivity. It was conducted with 140 Iranian M.A. EFL learners from Department of English at Islamic Azad University of Najafabad. In order to have a homogeneous sample, the second version of Quick Placement Test (QPT) was administered. Then, 85 lower ...

As reflective practice has become an influential factor in teacher professional development, teachers need some techniques to enhance their reflective teaching. In this light, this study was intended to examine: (a) whether self-evaluation techniques could promote English as Foreign Language (EFL) teachers’ reflective teaching, (b) whether EFL teachers who used self-evaluation techniques would ...

In this thesis, the optical characteristics of all-active microring resonators as lasers are studied. The structure of a semiconductor microring laser coupled to a bus waveguide is investigated. The scope of the study is to examine the microring’s laser operation and also emphasize the influence of the key design parameters on single mode and/or unidirectional operation, both being of major con...

is a genuine feature of this laser configuration, that also appears in other calculations. As can be concluded from Fig. 3, the use of a.efI in eqn. 1 is essential for a reasonable linewidth calculation of DFB lasers with a reflecting end facet. It can be shown that a comparably strong effect also occurs for two reflecting end facets with KL>2 and in the case of the phase-shifted DFB laser with...

This review focuses on theoretical foundations, experimental implementation and an overview of experimental results of the thermoreflectance spectroscopy as a powerful technique for temperature monitoring and analysis of thermal processes in semiconductor lasers. This is an optical, non-contact, high spatial resolution technique providing high temperature resolution and mapping capabilities. Th...

This review focuses on theoretical foundations, experimental implementation and an overview of experimental results of the thermoreflectance spectroscopy as a powerful technique for temperature monitoring and analysis of thermal processes in semiconductor lasers. This is an optical, non-contact, high spatial resolution technique providing high temperature resolution and mapping capabilities. Th...