Continuously tunable diode laser sources coupled to single-mode fiber are useful sources for fiber Bragg grating (FBG) strain sensors. A low-cost 1300 nm laser diode is anti-reflection coated making it nearly an LED. By coupling this coated laser to a short length of single-mode fiber containing a low-reflection FBG, which serves as
the new tunable laser output coupler, a tunable, fiber-coupled laser source is possible. The laser diode package is mounted in a temperature-controlled mount, and the FBG is mounted so it can be strained. By controlling both temperature and FBG strain, the laser can be continuously tuned across a 10 nm spectral range giving a narrow line laser source for use in strain sensors.