Relativistische photonische Bandlückenspiegel in der integrierten Optik
Elektronische Halbleiter, Bauelemente und Schaltungen, Integrierte Systeme, Sensorik, Theoretische Elektrotechnik
Zusammenfassung der Projektergebnisse
In this project we have theoretically and experimentally investigated interaction of a moving photonic band gap with light. We have shown that relativistic front in periodic waveguides can significantly change frequency, bandwidth and time sequence of the optical pulse. It was demostrated that theoretical description of these phenomena are better to be conducted in terms of temporal evolution of light spatial profiles in contrast to a common in nonlinear optics approach of spatial evolution of temporal profiles. Thought the second approach fits to the experimental scheme of temporal detection at defined positions in the optical path, it has fundamental difficulties in description of light close to the band edge of periodical waveguides. We have concentrated on the effect of light trapping and group velocity change by the front. In case of light trapping, a special situation was designed in which the front approaches a slow propagating signal, changes its frequency and accelerates to the velocity of the front. Such effect is also called optical push broom effect as it collects and compresses signal inside the front. We have shown that this effect can be realized in a periodic silicon waveguide using a free carrier front generated by two photon absorption of the pump pulse. Efficient conversion to the new frequency was demonstrated and compression in the order of 100 times was estimated. A pulse-pulse measurement is envisaged to confirm the compression experimentally. It was also shown that the optical push broom effect does a Fourier transform on the signal pulse. It would allow the realization of time lens or pulses with arbitrary pulse profile. In case of group velocity change with the front, conditions were identified to transfer light in the state of zero group velocity (light stopping) or to reverse time sequency of the pulse (time reversal). The stopping for several nanoseconds was proposed using writing and releasing pump pulses. The storage time will be limited by the residual dispersion at the zero-group-velocity point of the dispersion relation and by the scattering losses of the waveguide. Still a fully optical coherent storage on chip was proposed. All the proposed theoretical concepts are envisaged to be implemented experimentally in the follow up.
Projektbezogene Publikationen (Auswahl)
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Front-induced transitions. Nat. Photonics 13 (2019) 737
M. A. Gaafar, T. Baba, M. Eich & A. Y. Petrov
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Linear Schrödinger equation with temporal evolution for front induced transitions. Opt. Express 27 (2019) 21273
M. A. Gaafar, H. Renner, A. Y. Petrov & M. Eich
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Pulse time reversal and stopping by a refractive index front. APL Photonics 5 (2020) 080801
M. A. Gaafar, J. Holtorf, M. Eich & A. Y. Petrov
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Fourier optics with linearly tapered waveguides: Light trapping and focusing. APL Photonics 6 (2021) 066108
M. A. Gaafar, H. Renner, M. Eich & A. Y. Petrov
