Browsing by Author "McMeekin, S. G."
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- Optical modulation at around 1550 nm in an InGaAlAs optical waveguide containing an InGaAs/AlAs resonant tunneling diodePublication . Figueiredo, J. M. L.; Boyd, A. R.; Stanley, C. R.; Ironside, C. N.; McMeekin, S. G.; Leite, A. M. P.We report electroabsorption modulation of light at around 1550 nm in a unipolar InGaAlAs optical waveguide containing an InGaAs/AlAs double-barrier resonant tunneling diode ~RTD!. The RTD peak-to-valley transition increases the electric field across the waveguide, which shifts the core material absorption band edge to longer wavelengths via the Franz–Keldysh effect, thus changing the light-guiding characteristics of the waveguide. Low-frequency characterization of a device shows modulation up to 28 dB at 1565 nm. When dc biased close to the negative differential conductance region, the RTD optical waveguide behaves as an electroabsorption modulator integrated with a wide bandwidth electrical amplifier, offering a potential advantage over conventional pn modulators.
- Optical modulation in a resonant tunneling relaxation oscillatorPublication . Figueiredo, J. M. L.; Stanley, C. R.; Boyd, A. R.; Ironside, C. N.; McMeekin, S. G.; Leite, A. M. P.We report high-speed optical modulation in a resonant tunneling relaxation oscillator consisting of a resonant tunneling diode (RTD) integrated with a unipolar optical waveguide and incorporated in a package with a coplanar waveguide transmission line. When appropriately biased, the RTD can provide wide-bandwidth electrical gain. For wavelengths near the material band edge, small changes of the applied voltage give rise to large, high-speed electroabsorption modulation of the light. We have observed optical modulation at frequencies up to 14 GHz, associated with subharmonic injection locking of the RTD oscillation at the fundamental mode of the coplanar transmission line, as well as generation of 33 ps optical pulses due to relaxation oscillation.