Browsing by Author "Figueiredo, Jose M. L."
Now showing 1 - 2 of 2
Results Per Page
Sort Options
- Photo-detectors integrated with resonant tunneling diodesPublication . Romeira, Bruno; Pessoa, Luis M.; Salgado, Henrique M.; Ironside, C. N.; Figueiredo, Jose M. L.We report on photo-detectors consisting of an optical waveguide that incorporates a resonant tunneling diode (RTD). Operating at wavelengths around 1.55 m 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.
- Wireless interrogation of an optically modulated resonant tunnelling diode oscillatorPublication . Cantu, Horacio I.; Salgado, H. M.; Romeira, Bruno; Kelly, Anthony E.; Ironside, C. N.; Figueiredo, Jose M. L.In this work, a resonant tunnelling diode-photo-detector based microwave oscillator is amplitude modulated using an optical signal. The modulated free running oscillator is coupled to an antenna and phase locked by a wireless carrier that allows remote extraction of the information contained in the modulation. An off-the-shelf demodulator has been used to recover the envelope of the baseband data originally contained in the optical signal. Data were successfully transmitted at a rate of 1 MSym/s with a bit error rate below 10-6. (c) 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:1728-1730, 2013