Nanolasers and nanoLEDs are seen as potential sources for low-power optical interconnects. The enhancement of the spontanous emission rate (Purcell effect) related to the small volume has been perceived as a key aspect in the operation of these devices. The fundamental aspects of size scaling in practical nanolasers and nanoLEDs will be discussed in this talk. Firstly, experimental results on nanoLEDs coupled to waveguides on Si will be presented. The effect of surface recombination will be discussed, together with promising passivation methods. In the second part of the talk, a simple theoretical model based on rate equations will be used to investigate the ultimate limits to scaling. In this model, spontaneous and stimulated emission are treated on the same footing, leading to a consistent treatment of the rate enhancement due to the decreasing volume. The analysis shows that Purcell enhancement of spontaneous emission plays a limited role in practical structures, due to the unavoidable linewidth broadening, while the related volume dependence of the stimulated emission rate has a key impact on nanolaser dynamics.
The ability to produce narrow optical pulses has been extensively investigated in laser systems with promising applications in photonics such as clock recovery, pulse reshaping, and recently in photonics artificial neural networks using spiking signal processing. Here, we investigate a neuromorphic opto-electronic integrated circuit (NOEIC) comprising a semiconductor laser driven by a resonant tunneling diode (RTD) photo-detector operating at telecommunication (1550 nm) wavelengths capable of excitable spiking signal generation in response to optical and electrical control signals. The RTD-NOEIC mimics biologically inspired neuronal phenomena and possesses high-speed response and potential for monolithic integration for optical signal processing applications.
We experimentally investigate the synchronous response of two fiber-optic coupled optoelectronic circuit oscillators based on resonant tunneling diodes (RTDs). The fiber-optic synchronization link employs injection of a periodic oscillating optical modulated signal generated by a master RTD-laser diode (LD) oscillator to a slave RTD-photodetector (PD) oscillator. The synchronous regimes were evaluated as a function of frequency detuning and optical injection strength. The results show the slave RTD-PD oscillator follows the frequency and noise characteristics of the master RTD-LD oscillator resulting in two oscillators with similar phase noise characteristics exhibiting single side band phase noise levels below -100 dBc/Hz at 1 MHz offset from the carrier frequency. Optical synchronization of RTD-based optoelectronic circuit oscillators have many applications spanning from sensing, to microwave generation, and data transmission.
We investigate optoelectronic oscillator (OEO) configurations based on a laser diode driven by resonant tunnelling diode
(RTD) optical waveguide photo-detector (PD) oscillators, with an optical fiber feedback loop carrying a fraction of the
laser diode optical output that is re-injected into the OEO through the optical waveguide of the RTD-PD. In the
configurations reported here, we take advantage of the RTD negative differential resistance to provide electrical highbandwidth.
The optical fiber loop acts as a high quality optical energy storage element with low transmission loss. The
RTD based OEO can produces stable and low-phase noise microwave signals with attractive applications in photonics
and communication systems, mainly in fiber-optic based communication links since the RTD-OEO can be accessed both
optically and electrically.
Optoelectronic oscillators can provide low noise oscillators at radio frequencies in the 0.5-40 GHz range and in this
paper we review two recently introduced approaches to optoelectronic oscillators. Both approaches use an optical fibre
feedback loop. One approach is based on passively modelocked laser diodes and in a 40 GHz oscillator achieves up to 30
dB noise reduction. The other approach is based on resonant tunneling diode optoelectronic devices and in a 1.4 GHz
oscillator can achieve up to 30 dB noise reduction.
We present a review of Resonant Tunneling Diode (RTD) OptoElectronic Integrated Circuits (OEICs). Resonant
tunneling diodes (RTDs) can be relatively easily integrated on the same chip as optoelectronic components and in this
paper we discuss the integration of RTDs with laser diodes, electroabsorption modulators and photodiodes. The RTD
provides the OEIC with negative differential resistance over a wide bandwidth. RTDs are highly nonlinear devices and
by applying nonlinear dynamics we have recently gained considerable insight into the operation of the RTD OEICS and
that has allowed us to design, fabricate and characterize OEICs for wireless/photonic interfaces.
Recent work on an OptoElectronic Integrated Circuit (OEIC), the resonant tunneling diode-laser diode (RTD-LD) has
shown that it can act as an optoelectronic voltage controlled oscillator (OVCO). The RTD-LD oscillates because of the
negative differential resistance of the RTD and simply providing the RTD-LD with a dc voltage will cause it to oscillate
at frequencies determined by both the external components of the circuit and the value of the dc voltage. It has been
observed to oscillate at frequencies as high as 2.2GHz and be tunable from 1.8-2.2GHz as the dc voltage is tuned by
0.5V. Both monolithic and hybrid (separate RTD and LD chips) have been investigated. The hybrid RTD-LD has been
accurately modeled as a Liénard's oscillator - closely related to the Van der Pol oscillator. The model is a classic of
nonlinear systems theory and explains all of the observed operating features that include synchronization and chaotic
output. Applications include wireless to optical signal conversion where phase synchronization has been demonstrated to
transfer phase modulated signals from the wireless to the optical domain by modulating the RTD-LD OVCO to produce
a phase modulated optical sub-carrier.