THESIS
2018
xxix, 201 pages : illustrations ; 30 cm
Abstract
Quantum dot (QD) lasers operating in datacom and telecom wavelengths (1.3 and 1.55
μm) have been significant building blocks in inter/intra-chip optical interconnections as well
as long-haul communications. Although significant advances have been achieved in
improving the performance of the QD lasers, most of them have only been realized on the
native GaAs or InP substrates. It has been a long-standing desire to monolithically integrate
these high-performance lasers on silicon, which enables wafer-scale photonic integrated
circuits on the basis of CMOS manufacturing platform for silicon photonics.
In this thesis, we aim to produce efficient III-V quantum dot lasers epitaxially grown on
Si substrates, emitting at the 1.55 μm band. To realize this goal, challenges have to be settl...[
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Quantum dot (QD) lasers operating in datacom and telecom wavelengths (1.3 and 1.55
μm) have been significant building blocks in inter/intra-chip optical interconnections as well
as long-haul communications. Although significant advances have been achieved in
improving the performance of the QD lasers, most of them have only been realized on the
native GaAs or InP substrates. It has been a long-standing desire to monolithically integrate
these high-performance lasers on silicon, which enables wafer-scale photonic integrated
circuits on the basis of CMOS manufacturing platform for silicon photonics.
In this thesis, we aim to produce efficient III-V quantum dot lasers epitaxially grown on
Si substrates, emitting at the 1.55 μm band. To realize this goal, challenges have to be settled,
which mainly lie in achieving good QDs with strong optical emission together with a uniform
QD distribution, as well as obtaining a smooth InP buffer grown on Si substrates with
minimized defects generation. By utilizing the double-cap procedure, we were able to stack
the InAs/InAlGaAs QDs to enhance the optical properties; additionally, these self-assembled
QDs were inserted into the InP buffer to serve as dislocation filters.
Based on these efforts, low-temperature continuous-wave (CW) operation of QD
microdisk lasers (MDLs) grown on (001) Si was realized. To miniaturize the footprints of the
microlasers, subwavelength QD MDLs were produced, showing low thresholds, superior
characteristic temperatures and above room temperature operation, under pulsed optical
pumping.
Furthermore, we moved on to grow and fabricate the more practical electrically injected
Fabry-Perot lasers. By carefully tuning the growth parameters of QDs and leveraging the
V-grooved Si to lower dislocation densities in the QD laser structure, the first 1.55 μm band
room temperature electrical QD laser directly grown on Si was demonstrated, with a threshold
density as low as 1.8 kA/cm
2, and a high operation temperature up to 80°C.
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