Advances in Laser Technology and nonlinear Optical techniques can be effectively utilized for LIDAR
applications in space and atmospheric sciences to achieve better flexibility and control of the available optical power.
Using such devices, one can achieve highly accurate and resolved, measurement of the distribution for atmospheric
scattering layers. In the present investigation a diode double end pumped high repetition rate, multi wavelength Nd:YAG
laser is designed, fabricated and various laser beam parameters have been characterized for LIDAR applications.
Nonlinear optical techniques have been employed to generate higher harmonics like 532nm, 355nm and 266nm for
various spectral studies. The experimental setup mainly consists of two Fiber coupled pump laser diodes (Model FAP-
81-30C-800B, Coherent Inc, USA) with a maximum output power of 30Watt at a wavelength of 807-810nm at 30°C set
temperature. A second harmonic LBO crystal cut for critical phase matching placed within the laser resonator is provided
for converting a fraction of the fundamental beam to a second harmonic beam. A type II frequency tripling LBO nonlinear
crystal (cut for critical phase matching) is also located inside the laser resonator. The third harmonic beam and the
unconverted fundamental beam are then directed across a type I fourth harmonic LBO crystal cut for critical phase
matching where a portion of the fundamental beam and a portion of the third harmonic beam are converted to a fourth
harmonic frequency when both fundamental and third harmonic beams propagate through the frequency quadrupling
crystal. The resulting beams which are the fundamental (1064nm), second harmonic (532nm), third harmonic (355nm)
and fourth harmonic (266nm) are then directed to a fourth harmonic separator in which the fourth harmonic beam is
separated from the fundamental beam. A maximum average power of 12W at 1064nm, 8W at 532nm, 5W at 355nm and
3W at 266nm have been measured at a repetition rate of 10KHz. A minimum pulse width of 25ns have been observed.