Wireless Injection Locking and Phase Noise Reduction in a Semiconductor Laser driven by a Resonant Tunnelling Diode Nonlinear Oscillator [paper CI3.1]

The development of optoelectronic integrated circuits (OEIC) that combine optical and electronic functionalities on a single chip have been driven by numerous telecommunications applications including microwave-optical interfaces for radio-over-fiber picocellular networks for the next-generation wireless communication systems, also know as fourth-generation (4G) systems. The integration of a resonant tunnelling diode (RTD) with laser diode (LD) gives rise to a novel nonlinear optoelectronic oscillator, the RTD- LD oscillator, with innovative functionalities capable of various electro-photonic operation modes including optoelectronic voltage controlled oscillator and synchronization to low power RF signals. The circuit nonlinear behaviour is a consequence of the RTD nonlinear current-voltage characteristic that shows negative differential resistance region. This paper investigates by experimental evidence the potential application of the RTD-LD oscillator as a wireless-to- optical (WO) converter. The RTD-LD WO converter includes a patch antenna for directional reception of broadcasted signals at microwave frequencies. In the presence of radio-broadcasted signals with frequencies within the RTD-LD oscillator locking ranges the radio sub-carrier of the laser optical output follows the phase of the broadcasted signals with significant noise reduction around the locking frequencies. The circuit locking ranges around the oscillator's natural frequency and its sub-harmonics/harmonics frequencies are controlled by the oscillator quiescent bias voltage