Physics and Photonic Switching Applications of Nonlinear Semiconductor Laser Amplifiers.
Abstract
This dissertation studies the physics and potential applications of optically nonlinear semiconductor laser amplifiers. These devices are expected to play an important role in optical communication, distributed computing, and nonlinear optical processing. The most interesting feature of these devices is that they have optical gain, which results in a low switching power and in the possibility of cascading these devices. Nonlinear switching and optical bistability in nonlinear semiconductor laser amplifiers are obtained experimentally. Theoretical analysis of the measured steady-state switching power as a function of the initial detuning yields the linewidth enhancement factor and the change of the refractive index versus carrier density. This represents the first time that these parameters have been obtained using nonlinear laser amplifiers. The dynamical response of a nonlinear diode laser amplifier, especially at the turn-on of the device, is examined. Output spiking and ringing are directly obtained experimentally in the time domain. In the frequency domain, an asymmetric spectral broadening is measured, for the first time, and is manifested as a dynamic frequency chirp associated with the turn-on spike at the onset of light injection. Our calculations show that the duration of the turn-on spike is limited mostly by the cavity photon lifetime. Shorter optical pulses can be obtained with reduced cavity length. A complete set of new experiments are performed to investigate the potential of nonlinear diode laser amplifiers in photonic switching applications. Their operation as a narrow-band filter in wavelength division demultiplexing is studied in a two-channel experiment. Wavelength conversion in these devices is demonstrated at bit rates up to 1.4 Gbit/s. This wavelength conversion rate is a measure of the switching speed of the nonlinear diode laser amplifier. A novel scheme is developed to optically convert a high duty -cycle data signal to a low duty-cycle data signal, which could have important applications in optical time division multiplexing. Spectral logics are demonstrated where the inputs and the output each has its own wavelength. And finally, an optically addressable generalized nonblocking optical crossbar switch based on nonlinear diode laser amplifiers is proposed. Experimental results show that space division switching can be achieved with a reconfiguration time of less than 1 ns and a per channel data bandwidth of 1.4 Gbit/s. An overview of the current status of nonlinear semiconductor laser amplifiers is presented and their future prospects are discussed.
- Publication:
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Ph.D. Thesis
- Pub Date:
- 1993
- Bibcode:
- 1993PhDT........74P
- Keywords:
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- Physics: Optics; Engineering: Electronics and Electrical