The generation of optical pulses with parabolic time intensity profiles is experimentally demonstrated. A Mode Locked Laser
(MLL) that generates near transform limited pulses with a gaussian optical spectrum are temporally stretched using a linearly
chirped fiber Bragg grating. The temporal intensity profile of the stretched pulses matches the optical spectrum of the laser
due to frequency-to-time mapping. An amplitude modulator is driven by a carefully designed voltage signal to result in
parabolic pulses. Experimental results of pulse shaping with a MLL input source are presented, and show good agreement
with modeling results. Parabolic pulse generation using a CW laser source is also demonstrated and a deviation of less than
3% from an ideal parabola is observed.
A chirped fiber Bragg grating with a dispersion of 1651ps/nm is used to generate temporally stretched,
frequency chirped pulses from a passively mode locked fiber laser that generates pulses of ~1ps (FWHM)
duration at a repetition rate of 20MHz with 3.5mW average power (peak power of 175W). The use of a
chirped fiber Bragg grating enables the generation of temporally stretched pulses with low peak power so
that non-linear effects in the fiber can be avoided. A fiber based interferometeric arrangement is used for
interfering a reference signal with the reflected signal from the target to realize a coherent heterodyne
detection scheme. In the RF domain, the detected heterodyne beat frequency shifts as the target distance is
changed. A round trip target distance of 14km in air is simulated using 9.3km of optical fiber and a
resolution of less than a millimeter is observed.