Photorefractive quantum well p-i-n diode: Design for high resolution and broad bandwidth

摘要

Design of quantum-well structure and cladding layers is a key issue to improve the performance of photorefractive semiconductor multiple quantum well (MQW) p-I-n diodes operated in the longitudinal-field geometry. We investigated device structures for (ⅰ) improving spatial resolution and (ⅱ) expanding spectral bandwidth. Reduction of potential difference between the MQW region and the cladding layer has significantly improved the spatial resolution in InGaAs/GaAs p-I-n diode. We also propose a new approach to expand the diffraction bandwidth by employing asymmetric coupled quantum well (ACQW) structures. Diffraction has been observed at a spectral range over 30 nm in AlGaAs/GaAs ACQW p-I-n diode. Photorefractive ACQW devices will be suitable for applications such as optical short-pulse processing.