The broadband (Fabry-Perot) wavelength locker is a thermally stable, air-gapped, etalon-based device that can be used to stabilize laser sources for high-density WDM applications and tunable lasers. Our 50 GHz, free spectral range (FSR) designs are industry-standard products. The broadband wavelength locker has a wide capture range and excellent wavelength accuracy. The temperature sensor, included with every locker, can be used to calibrate out thermal effects when even higher wavelength accuracy is required or when using a very narrow FSR locker.