External cavity with a pair of two Fiber Bragg gratings at the front and back facet of a laser diode

摘要

A semiconductor laser chip is placed in between two Fiber Bragg gratings (FBGs), which are used as external cavities for the laser, to stabilize its center wavelength and to reduce its bandwidth.;The first FBG is placed at the front facet of the laser chip, while the second FBG is placed on the back facet of the chip. The two FBGs are used to form an external cavity. Both FBGs can have same central wavelengths, different reflectivities and different bandwidths. The distance between the laser chip and the FBGs can varies from few millimeters to several meters. Since the FBGs have a very small wavelength drift with temperature fluctuations, the semiconductor laser has a stable center wavelength output. Another benefit of this setup is that the bandwidth of laser diode is also reduced.