We studied the novel structure for improving the emission properties of semiconductor light sources both theoretically
and experimentally. The proposed structure is a semiconductor pillar buried in a metal except for one end surface of the
pillar. Photons are extracted only from the air-exposed surface. The structure consists of the GaAs nanopillar structures
embedded in metal and is analyzed by the finite-difference-time-domain method. InAs quantum dots buried in a GaAs
pillar are assumed to be the photon emitters. Simulations are performed on GaAs pillars with different diameters buried
in Niobium. Consequently, the simulation showed 75% light extraction efficiency from the pillar to air with the
optimization of the structure. In addition, we experimentally measured photoluminescence intensities of up to 40 times
enhancement in embedded structures compared to normal pillar structure. These are promising for future applications to
overcome single photon sources.
Quantum information processing and quantum cryptography are expected to realize highly secure future information
networks. How to control photon qubits will be one of the major issues for this direction, but the technologies related to
generations and detections of individual photons are still being developed. Semiconductor quantum dots (QDs) have
been expected to play major role for on-demand generations of single photons as well as entangled photon pairs. In this
talk, photon generation processes from a single QD will be studied for the control of the quantum states of generated
photons. Generation of entangled photon pairs from QDs based on biexciton-exciton cascade recombination processes is
presently in a difficult situation due to exciton states energy splitting related to growth-related issues. An approach to
open new paradigm will be discussed with preliminary results.
The coherent emission process at excitonic resonance was first investigated in short-period ZnSe/ZnSxSe1-x (x equals 0.18) superlattices with one period of 50 A/50 A and 19 A/19 A by observing a temporal profile with subpicosecond time resolution, of reflected pulses in the Brewster-angle configuration. As a result, an almost background-free signal with nonresonant contribution reduced greatly, was observed reflecting free induction decay (FID) of coherently driven exciton polarization. In particular, a beat signal of FID was clearly observed for the first time, which arises from interference effect between a few split spectral lines of the relevant exciton. Further, it was confirmed that the decay spread of FID becomes faster as the power density of incident pulse was increased for the SL sample with a thicker well. The results may be explained qualitatively by a simple model with the knowledge of the exciton structure as well as a preliminary data of the phase relaxation time obtained by four- wave-mixing measurement. The present results have provided a basis for that the transient Brewster-angle reflection spectroscopy serves as a powerful tool for exploring coherent interaction of exciton with light.
Conference Committee Involvement (14)
Physics and Simulation of Optoelectronic Devices XXXI
31 January 2023 | San Francisco, California, United States
Physics and Simulation of Optoelectronic Devices XXX
24 January 2022 | San Francisco, California, United States
Physics and Simulation of Optoelectronic Devices XXIX
6 March 2021 | Online Only, California, United States
Physics and Simulation of Optoelectronic Devices XXVIII
3 February 2020 | San Francisco, California, United States
Physics and Simulation of Optoelectronic Devices XXVII
5 February 2019 | San Francisco, California, United States
Physics and Simulation of Optoelectronic Devices XXVI
29 January 2018 | San Francisco, California, United States
Physics and Simulation of Optoelectronic Devices XXV
30 January 2017 | San Francisco, California, United States
Physics and Simulation of Optoelectronic Devices XXIV
15 February 2016 | San Francisco, California, United States
Physics and Simulation of Optoelectronic Devices XXIII
9 February 2015 | San Francisco, California, United States
Physics and Simulation of Optoelectronic Devices XXII
3 February 2014 | San Francisco, California, United States
Physics and Simulation of Optoelectronic Devices XXI
4 February 2013 | San Francisco, California, United States
Physics and Simulation of Optoelectronic Devices XX
23 January 2012 | San Francisco, California, United States
Physics and Simulation of Optoelectronic Devices XIX
24 January 2011 | San Francisco, California, United States
Physics and Simulation of Optoelectronic Devices XVIII
25 January 2010 | San Francisco, California, United States
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