12 research outputs found
Coherently coupled photonic-crystal surface-emitting laser array
The realization of a 1 × 2 coherently coupled photonic crystal surface emitting laser array is reported. New routes to power scaling are discussed and the electronic control of coherence is demonstrated
Purcell-Enhanced Single Photons at Telecom Wavelengths from a Quantum Dot in a Photonic Crystal Cavity
Quantum dots are promising candidates for telecom single photon sources due
to their tunable emission across the different low-loss telecommunications
bands, making them compatible with existing fiber networks. Their suitability
for integration into photonic structures allows for enhanced brightness through
the Purcell effect, supporting efficient quantum communication technologies.
Our work focuses on InAs/InP QDs created via droplet epitaxy MOVPE to operate
within the telecoms C-band. We observe a short radiative lifetime of 340 ps,
arising from a Purcell factor of 5, owing to interaction of the QD within a
low-mode-volume photonic crystal cavity. Through in-situ control of the sample
temperature, we show both temperature tuning of the QD's emission wavelength
and a preserved single photon emission purity at temperatures up to 25K. These
findings suggest the viability of QD-based, cryogen-free, C-band single photon
sources, supporting applicability in quantum communication technologies
1.5 {\mu}m Epitaxially Regrown Photonic Crystal Surface Emitting Laser Diode
We present an InP-based epitaxially regrown photonic crystal surface emitting
laser diode, lasing in quasi- CW conditions at 1523nm.Comment: 4 pages, 5 figures, journal submission for revie
Optics of III-V semiconductor quantum dots : fundamental properties and applications
EThOS - Electronic Theses Online ServiceGBUnited Kingdo
Polarization-pinning in substrate emission multi-mode vertical-cavity surface-emitting lasers using deep trenches
We investigated the stable polarization-pinning properties of substrate emission InGaAs-based 980 nm multi-mode vertical-cavity surfaceemitting lasers (VCSELs). For the multi-mode 40 um diameter aperture VCSELs, we introduced 30 lm wide, 9 lm depth deep trenches that
are 15 lm away from the cavity aperture. The VCSELs with trench structure produced higher transverse-electric (TE) polarized light output
power, as compared with transverse-magnetic (TM) polarized light output power, namely, the effective TM polarization suppression was
realized. These trench-etched VCSELs exhibited a 7.5 dB orthogonal polarization suppression ratio with 16.8 mW of light output power at
60 mA of current injection. The dominant TE polarization distribution was observed in polarization-resolved near-field images of spontaneous
and stimulated emission due to the induced strain by the etched trenches
Proposal for common active 1.3-μm quantum dot electroabsorption modulated DFB laser
Opportunities for the monolithic integration of a novel common quantum dot (QD)-active electroabsorption modulated laser are explored. An electric-field and temperature-dependent spectroscopic study of optical absorption and gain are presented in the state-of-the-art 1.3-μm In(Ga)As/GaAs QD active material. The unique gain/absorption spectral shape, attributed to the QD's density of states, allows for a number of possible modulation schemes dependent upon the selected laser wavelength detuning from the gain peak. Intensity modulation and change in absorption, leading to negative chirp operation, are demonstrated via absorption spectroscopy and gain measurement of eight-layer-stack QD-active material. Such a device would be able to provide positive or negative chirp dependent upon modulation scheme and gain/Bragg wavelength detuning
Proposal for Common Active 1.3-<inline-formula> <tex-math notation="LaTeX"> </tex-math> </inline-formula>m Quantum Dot Electroabsorption Modulated DFB Laser
Mode control in photonic crystal surface emitting lasers through external reflection
In this paper, we show the effect of lateral external
optical feedback on an all semiconductor photonic crystal surface
emitting laser (PCSEL). Initially, a PCSEL is grown and fabricated
with a square lattice of triangles, the device is shown to
operate electrically driven at room temperature under continuous
wave condition. We investigate, theoretically and experimentally,
the effect of lateral feedback on the performance of photonic crystal
lasers. Demonstrating a reduction in mode competition and
a modification to spatial mode distribution, opening routes to all
electronic beam shaping and divergence control
Development of AlGaAs avalanche diodes for soft X-ray photon counting
We report on the performance of avalanche photodiodes (APDs) based on the wide band gap material AlGaAs which have been developed for soft X-ray spectroscopy applications. A number of diode types with different layer thicknesses have been characterised. The temperature dependence of the avalanche multiplication process at soft X-ray energies in Al 0.8Ga 0.2As APDs was investigated at temperatures from +80°C to -20°C. X-ray spectra from a 55Fe radioactive source show these diodes can be used for spectroscopy with promising energy resolution (0.9-2.5keV) over a wide temperature range. The temperature dependence of the pure electron initiated multiplication factor (M e) and the mixed carrier initiated avalanche multiplication factor (M mix) were experimentally measured. The experimental results are compared with a spectroscopic Monte Carlo model for Al 0.8Ga 0.2As diodes from which the temperature dependence of the pure hole initiated multiplication factor (M h) is determined. © 2011 IEEE