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Article
Thermal Management of Vertical External Cavity Surface Emitting Laser Grown on GaAs Substrate

Author: G. Balluo
Journal: Iraqi Journal of Applied Physics المجلة العراقية للفيزياء التطبيقية ISSN: 18132065 23091673 Year: 2017 Volume: 13 Issue: 2 Pages: 15-18
Publisher: iraqi society for alternative and renewable energy sources and techniques الجمعية العراقية لمصادر وتقنيات الطاقة البديلة والمستجدة

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Abstract

In a VECSELs, it seems that most of the heat comes from the pumping mechanism which is the external laser that is exciting the active medium. The pump photons have higher energy than the emitted photons and thus the energy difference is dissipated as heat in the active medium. As the temperature increases in the active medium the excited carriers star escaping the quantum wells until the laser gain is depleted and the power output decreases. Thermal management is crucial for VECSEL power performance and it is usually addressed by using heat spreader plates and heat sinks as will be explained next.


Article
Using Substrate Removal Technique for GaAs-Based VECSEL Optimization

Author: C.L. Yang
Journal: Iraqi Journal of Applied Physics المجلة العراقية للفيزياء التطبيقية ISSN: 18132065 23091673 Year: 2017 Volume: 13 Issue: 2 Pages: 23-26
Publisher: iraqi society for alternative and renewable energy sources and techniques الجمعية العراقية لمصادر وتقنيات الطاقة البديلة والمستجدة

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Abstract

A combination of two types of etching mechanisms: physical etching which relies on physical interaction of particles that erode the surface, and wet/dry etching that relies on chemical reactions to erode the surface, is used to remove substrates with thickness between 300 and 500µm. First, the substrate is mechanically thin down to about 100µm and then wet etching or dry etching is applied. The substrate removal of GaAs was successfully achieved as verified in the x-ray diffraction etch analysis.


Article
Synchronization in Optically Coupled Chaotic Systems by Optical Feedback
التوافق في الأنظمة الفوضوية المقترنة بصريا بواسطة التغذية الخلفية البصرية

Authors: Younis Th. Younis --- Salam K. Mousa --- Sora F. Abdalla --- Ahmed K. Ahmed --- et al.
Journal: Iraqi Journal of Applied Physics المجلة العراقية للفيزياء التطبيقية ISSN: 18132065 23091673 Year: 2017 Volume: 13 Issue: 1 Pages: 11-16
Publisher: iraqi society for alternative and renewable energy sources and techniques الجمعية العراقية لمصادر وتقنيات الطاقة البديلة والمستجدة

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Abstract

An experimentally observations of chaos synchronization have been investigated between two optically coupled laser diodes. Two schemes of optical injection, bidirectional and unidirectional optical injections have been used. One of the two lasers MLD exhibits optical chaos due to external optical feedback by fiber mirror and the other laser diode SLD exhibits optical chaos by optical injection from the first one. The chaotic dynamics of both lasers were a function of laser diodes drive current. Synchronization and Anti-synchronization between two coupled laser diodes have been observed, and ensured by different measurements like time series matching, correlation diagram (phase form) of amplitudes of coupled chaotic signals ,spectrum components coinciding of coupled chaotic signals have been used for both injection schemes. Cross correlation function has been used to measure quality of synchronization in unidirectional injection scheme and it was a function of slave laser diode's current.


Article
Scrutiny of the dynamics of quantum dot semiconductor lasers
تفحص حركيات ليزرات النقطة الكمية

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Abstract

The present paper introduces a numerical simulation results of the study from semiconductor quantum dot laser via the solution of four- equations model that describe temporal variations of carrier numbers in the wetting layer, N_wl, in the two- fold degenerate ground state, N_GS, and in the four- fold degenerate excited state, N_ES, and the number of photons, S, emitted from the GS. Varieties of dynamics have been seen to occur as a result of the variation of the parameters that appeare in the above mentioned model.

في البحث الحالي نقدم نتائج المحاكات العددية لدراسة حركيات ليزر النقطة الكمية عن طريق حل انموذج رياضي يتكون من اربعة معادلات تصف التغيرات الزمنية لعدد الحاملات في منطقة الترطيب وفي الحالة الأرضية ذات الأنحلال الثنائي والحالة المتهيجة ذات الأنحلال الرباعي في النقطة الكمية واخيراً عدد الفوتونات المنبعثة من الحالة الأرضية . حصل العديد من الحركيات عن طريق تغير العديد من المتغيرات التي يحتويها الأنموذج اعلاه.

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