Aj Seeds

Distribution of multiband THz wireless signals over fiber

Terahertz wireless communication is receiving great interest from researchers and industries, thanks to the new spectral windows between 0.1 and 1 THz offering opportunities for ultra-high-data-rate wireless transmission. Wavelength division multiplexing for wireless-over-fiber is foreseen as an enabling technique to support connection between base stations and a central station. This paper reviews architectures for photonic distribution and generation of multiband signals for sub- THz wireless communications, giving rates up to 100 Gb/s (20 Gb/s per band) using the full spectrum between 220 GHz and 280 GHz for downlink wireless transmission, and 10 Gb/s for uplink using on-off keying.

InAs/GaAs quantum-dot light emitters monolithically grown on Si substrate

We report on high quality GaAs-on-Si layers with low threading dislocations obtained by a combination of nucleation layer and dislocation filter layers using the molecular beam epitaxy (MBE) growth method. As a result, we achieved a Si-based electrically pumped 1.3 μm InAs/GaAs quantum dot (QD) laser that lases up to 111°C with a lasing threshold of 200 A/cm2, and a single facet output power exceeding 100 mW at room temperature. In addition to Si-based lasers, we also demonstrated the first Si-based InAs/GaAs QD superluminescent light-emitting diode (SLD), from which a close-to-Gaussian emission with a full width at half maximum (FWHM) of ~114 nm centered at ~1258 nm and maximum output power of 2.6 mW has been achieved.

Monolithically grown superluminescent diodes on germanium and silicon substrates

We demonstrate the first InAs/GaAs quantum-dot (QD) superluminescent diode (SLD) monolithically grown on both Ge and Si substrates by molecular beam epitaxy. The QD SLDs on Ge substrates exhibit a 3 dB emission bandwidth of ~60 nm with output power of 27 mW at room temperature, and operates up to 100 °C. We also report the first QD SLD monolithically grown on a Si substrate. A two-section ridge structure has been used to achieve a close-to-Gaussian emission spectrum of 114 nm centered at ~1255 nm wavelength, with a maximum output power of 2.6 mW at room temperature.

1.3µm InAs/GaAs Quantum-Dot Laser Monolithically Grown on Si Substrates Using InAlAs/GaAs Dislocation Filter Layers

We report on the operation of electrically pumped 1.3µm InAs QD laser directly grown on a Si substrate using InAlAs/GaAs dislocation filter layers with a threshold current density of 194A/cm2 and output power of ~80mW.

A room temperature electrically pumped 1.3-µm InAs quantum dot laser monolithically grown on silicon substrates

We present a room-temperature 1.3-µm InAs/GaAs quantum dot laser monolithically grown on Si(100). The threshold current at 20°C was 725A/cm2 and the emission wavelength was 1.302µm. The laser was operated in pulsed mode. The growth was enabled via the optimisation of the temperature of the initial nucleation layer of GaAs.