Space-time information processing with femtosecond laser pulses

Abstract

Ultrashort pulse laser technology has recently experienced significant advances, producing high peak power pulses of optical radiation few femtoseconds in duration, corresponding to only few cycles of its fundamental frequency. The future progress of this area is inevitable due to the unique properties of ultrashort laser pulses that are crucial for various science and engineering application areas including optical signal processing, secure optical communications, storage, medical and biomedical imaging, chemistry and physics. A common feature of these applications relies on our ability to control the shape of the ultrashort pulses15, store and retrieve them6 as well as, conversely, our ability to detect the shape of the ultrashort pulses7. In this paper we discuss examples on utilizing ultra-fast space-time optical processing for implementing data formats suitable for direct interface and transmission through an optical fiber. Examples on using femtosecond laser pulses for information storage and memory access as well as modulation and detection of information will be addressed. Specifically, we present our recent results on femtosecond pulse imaging by nonlinear three wave mixing and 3-D nonvolatile spectral domain storage of femtosecond pulses. There exists a bandwidth capacity mismatch between optical fiber and electronic devices, which can be used to increase the speed, reduce latency, increase security and reliability in the transmission and distribution of information. To implement these applications, an alloptical multiplexer performing space-to-time (i.e. , parallel-to-serial) transformation at the transmitter and a demultiplexer performing time-to-space (i.e., serial-to-parallel) transformation at the receiver will need to be constructed810. For efficient bandwidth utilization, these processors need to be operated at rates determined by the bandwidth of the optical pulses. Such space-time optical processors have been constructed and applied for pulse shaping, filtering, and space-to-time multiplexing and time-to-space demultiplexing11'12. Another example exploits applications benefiting from an optical memory that will store and retrieve information in a format suitable for direct interface and transmission through an optical fiber network, thereby, providing optimal performance in terms of hardware complexity, memory and network capacity, bandwidth, and latency. In this example a spatial image information need to be converted into time domain. The corresponding data sequence in time is stored employing spectral domain 3-D volume holographic recording13. When the stored data is read out of the spectral domain storage system, the output spectrum is converted back into time sequence and sent through the all-optical fiber network to the user node. At the user node the time sequence is converted to lower rate parallel channels in space domain for optical or electronic filtering and detection.