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

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