We report on photo-detectors consisting of an optical waveguide that incorporates a resonant tunneling diode (RTD). Operating at wavelengths around 1.55 μm in the optical communications C band we achieve maximum sensitivities of around 0.29 A/W which is dependent on the bias voltage. This is due to the nature of RTD nonlinear current-voltage characteristic that has a negative differential resistance (NDR) region. The resonant tunneling diode photo-detector (RTD-PD) can be operated in either non-oscillating or oscillating regimes depending on the bias voltage quiescent point. The oscillating regime is apparent when the RTD-PD is biased in the NDR region giving rise to electrical gain and microwave self-sustained oscillations Taking advantage of the RTD's NDR distinctive characteristics, we demonstrate efficient detection of gigahertz (GHz) modulated optical carriers and optical control of a RTD GHz oscillator. RTD-PD based devices can have applications in generation and optical control of GHz low-phase noise oscillators, clock recovery systems, and fiber optic enabled radio frequency communication systems.

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Digitized radio-over-fiber (D-RoF) transport schemes are being pointed as viable alternative solutions to their analog counterparts, in order to avoid distortion/dynamic range problems. Here we propose a novel D-RoF architecture that takes advantage of a bandpass sigma-delta modulator at the transmitter which subsequently permits the usage of a simpler/cheaper base station that avoids the employment of a digital to analog converter. The proposed architecture exploits the properties of the digital signal to enable the extraction of an higher carrier frequency through the employment of a bandpass filter. Furthermore, we present a comprehensive analysis regarding the impact of a low-cost electro-optic modulation on the quality of received demodulated signal. Finally, a comparison performance analysis between the conventional D-RoF and the proposed architecture is presented. We conclude that although the proposed architecture performs similarly to conventional D-RoF schemes, it is more competitive for either upgrading installed systems as well as for new deployments.