Development of a 1310-nm, coherent laser radar with RF pulse compression

NASA, ESA, and NASDA are planning to launch several satellites with LIDARs on board to measure ice sheet surface elevation, vegetation characteristics, and aerosol characteristics. LIDARs on these satellites will transmit short, high-peak power pulses to obtain adequate detection sensitivity and resolution. The disadvantages of high-peak power transmitters are that they require high-current power supplies and have low PRFs and limited lifetime. At The University of Kansas the authors are developing a pulse compression LIDAR featuring reduced peak power requirements and increased PRF to obtain more dense sampling. They have developed and have reported (IGARSS'99) 1550-nm fiber-optic based, coherent laser radar (lidar) that uses traditional RF pulse compression and digital signal processing techniques to enhance its range measurement capability. They have since migrated the wavelength to 1310 nm to improve the sensitivity to snow and ice while continuing to exploit the commercially available fiber-optic components such as distributed-feedback (DFB) lasers, modulators, and praseodymium-doped flouride fiber amplifiers (PDFFAs). To improve the radiometric sensitivity beyond that of the direct detection receiver, they have also developed a polarization-diverse, superheterodyne receiver. They present system design details, results of theoretical performance analyses, and performance test results.