A novel, sensitive, simple, and robust strain interrogation technique is an
alyzed and experimentally tested. By locking a laser wavelength to the midr
eflection wavelength of a standard fiber Bragg grating and measuring the er
ror signal, we achieve high dynamic strain sensitivity of 45 picostrain/roo
t Hz at 3 kHz, where the dominant noise in the experiment is the laser freq
uency noise. (C) 1998 Optical Society of America.