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Room Temperature Operation of Quantum Cascade Lasers Monolithically Integrated Onto a Lattice-Mismatched Substrate
Title
Room Temperature Operation of Quantum Cascade Lasers Monolithically Integrated Onto a Lattice-Mismatched Substrate.
Creator
Go, Rowel, Lyakh, Arkadiy, Delfyett, Peter, Likamwa, Patrick, Wu, Shintson, University of Central Florida
Abstract / Description
The experimental results of a 40-stage indium phosphide (InP) based quantum cascade laser (QCL) grown on a lattice-mismatched gallium arsenide (GaAs) substrate with metamorphic buffer (M-buffer) will be discussed. The QCL's strain-balanced active region was composed of Al0.78In0.22As/In0.73Ga0.27As and an 8 (&)#181;m-thick all-InP waveguide. Since the M-buffer was insulating, the wafer was processed into ridge-waveguide chips with lateral current injection scheme. Laser chips with high...
Show moreThe experimental results of a 40-stage indium phosphide (InP) based quantum cascade laser (QCL) grown on a lattice-mismatched gallium arsenide (GaAs) substrate with metamorphic buffer (M-buffer) will be discussed. The QCL's strain-balanced active region was composed of Al0.78In0.22As/In0.73Ga0.27As and an 8 (&)#181;m-thick all-InP waveguide. Since the M-buffer was insulating, the wafer was processed into ridge-waveguide chips with lateral current injection scheme. Laser chips with high reflection (HR) coating delivered total peak power in excess of 200 mW at cryogenic temperature (78 K), and lasing was observed up to 230 K. Partial HR coating was then utilized on the front facet to extend lasing range up to 303 K. After 200 minutes of preliminary reliability testing at maximum power, no sign of performance degradation was observed. Initial results of InP-based QCL on germanium-coated silicon substrate with M-buffer will also be covered in this work.
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Date Issued
2018
Identifier
CFE0007568, ucf:52564
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0007568
ELECTRO-OPTICAL AND ALL-OPTICAL SWITCHING IN MULTIMODE INTERFERENCE WAVEGUIDES INCORPORATING SEMICONDUCTOR NANOSTRUCTURES
Title
ELECTRO-OPTICAL AND ALL-OPTICAL SWITCHING IN MULTIMODE INTERFERENCE WAVEGUIDES INCORPORATING SEMICONDUCTOR NANOSTRUCTURES.
Creator
Bickel, Nathan, LiKamWa, Patrick, University of Central Florida
Abstract / Description
The application of epitaxially grown, III-V semiconductor-based nanostructures to the development of electro-optical and all-optical switches is investigated through the fabrication and testing of integrated photonic devices designed using multimode interference (MMI) waveguides. The properties and limitations of the materials are explored with respect to the operation of those devices through electrical carrier injection and optical pumping. MMI waveguide geometry was employed as it offered...
Show moreThe application of epitaxially grown, III-V semiconductor-based nanostructures to the development of electro-optical and all-optical switches is investigated through the fabrication and testing of integrated photonic devices designed using multimode interference (MMI) waveguides. The properties and limitations of the materials are explored with respect to the operation of those devices through electrical carrier injection and optical pumping. MMI waveguide geometry was employed as it offered advantages such as a very compact device footprint, low polarization sensitivity, large bandwidth and relaxed fabrication tolerances when compared with conventional single-mode waveguide formats. The first portion of this dissertation focuses on the characterization of the materials and material processing techniques for the monolithic integration of In0.15Ga0.85As/GaAs self-assembled quantum dots (SAQD) and InGaAsP/InGaAsP multiple quantum wells (MQW). Supplemental methods for post-growth bandgap tuning and waveguide formation were developed, including a plasma treatment process which is demonstrated to reliably inhibit thermally induced interdiffusion of Ga and In atoms in In0.15Ga0.85As/GaAs quantum dots. The process is comparable to the existing approach of capping the SAQD wafer with TiO2, while being simpler to implement along-side companion techniques such as impurity free vacancy disordering. Study of plasma-surface interactions in both wafer structures suggests that the effect may be dependent on the composition of the contact layer. The second portion of this work deals with the design, fabrication, and the testing of MMI switches which are used to investigate the limits of electrical current control when employing SAQD as the active core material. A variable power splitter based on a 3-dB MMI coupler is used to analyze the effects of sub-microsecond electrical current pulses in relation to carrier and thermal nonlinearities. Electrical current controlled switching of the variable power splitter and a tunable 2 x 2 MMI coupler is also demonstrated. The third part of this dissertation explores the response of In0.15Ga0.85As/GaAs SAQD waveguide structures to photogenerated carriers. Also presented is a simple, but effective, design modification to the 2 x 2 MMI cross-coupler switch that allows control over the carrier distribution within the MMI waveguide. This technique is combined with selective-area bandgap tuning to demonstrate a compact, working, all-optical MMI based switch.
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Date Issued
2010
Identifier
CFE0003220, ucf:48568
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0003220