Optical pulse compression for laser radar and communications
Abstract
The classical theory for compression of optical pulse in linear, dispersive media has been generalized to include a carrier frequency which varies quadratically as well as linearly with time. The nonlinearly chirped pulse becomes temporarily compressed upon propagating through a strongly dispersive medium. The group delay in the strongly dispersive propagation medium varies quadratically with carrier frequency. This theory has been applied to an experimental configuration of two gratings oriented to give strong dispersion of group delay. Objectives are to determine the influence of strong dispersion upon the shape and width of the compressed pulse. Results indicate that a grating-pair delay medium is feasible which is capable of compressing a linearly chirped 88 ns wide pulse at 10.6 micrometers wavelength to a final width of 0.8 ns. However, strong dispersion does distort the envelope of the compressed pulse so that it is no longer strictly the Fourier transform of the envelope of the original pulse. Addition of a nonlinear chirp to the incident pulse, in the form of a quadratic change in carrier frequency with time, causes the output to be broken into a series of pulses. The sub-pulses in this series are much narrower than the incident pulse, and exhibit increasingly larger gain in peak intensity over the incident pulse toward the end of the pulse train.
- Publication:
-
NASA STI/Recon Technical Report N
- Pub Date:
- August 1978
- Bibcode:
- 1978STIN...7915298M
- Keywords:
-
- Laser Applications;
- Optical Communication;
- Optical Radar;
- Pulse Compression;
- Fourier Transformation;
- Frequency Modulation;
- Laser Outputs;
- Lasers and Masers