Slow Light in Semi-Conductor Quantum Well Waveguides

Abstract

Abstract : The main objective of the program is to investigate various physical phenomena and device structures that can lead to potential applications to all optical storage and processing. The physical effects include electro-magnetic ally induced transparency (EIT), coherent population oscillation (CPO) in semiconductor quantum wells (QW) or dots. We carried out experimental implementation of EIT from electron spin coherence in a GaAs quantum well waveguide for the first time. We designed and fabricated the waveguide structure. We also designed and fabricated a miniature waveguide coupler attached to a cold finger in an optical cryostat. The EIT experiment using double-V energy configuration was carried out for the first time on a (110) QW waveguide. An absorption dip of tilde 10% indicates a slow down factor of 1000 was obtained with a spectral width 1GHz at 4K. From the spectral width, the spin coherence lifetime can be inferred to be tilde 1 ns at 4K. We carried out frequency-resolved measurements of electron spin coherence lifetime from the measured EIT spectral linewidth. An asymmetry in the resonance lineshape was observed. All results will be critical for understanding the physical properties of (110) QW waveguide and implementation of optical delay lines for signal processing.