Wideband frequency modulation of a mode-locked fiber laser.
We have demonstrated wideband frequency modulation of the frequency comb lines of a high-repetition-rate fiber laser. With a modulation frequency of only approximately 10 kHz, we have generated modulation indices in excess of 250. Although internally modulated, the laser remains stable with 2-kHz linewidths, and thus the 10-kHz modulation sidebands are still clearly resolved even after propagation over several hundred kilometers. This unique characteristic is used for simultaneous measurement of propagation distances to 1-m resolution and velocities of less than 3 mm/s over a distance of greater than 50 km.
Fatemi
F K
FK
Optical Sciences Division, Naval Research Laboratory, Washington, DC 20375, USA. ffatemi@ccs.nrl.navy.mil
Lou
J W
JW