A grating inscribed in the core with UV or femtosecond light, reflecting the Bragg wavelength, twice the effective index times the grating period. Fiber lasers use a high-reflectivity and a low-reflectivity FBG as their cavity mirrors, so the whole laser stays inside glass. Because the reflected wavelength shifts with strain and temperature, about 10 pm per degree C near 1550 nm, FBGs are also widely used as sensors.
HR grating's at 99.5 and the OC grating at 10 percent, both centered on 1080, splice them on either end of the gain fiber.
Also heard as
- FBG
- Bragg grating
Related terms
Fiber laser
A laser whose gain medium is an optical fiber with a rare-earth-doped core, pumped by diodes.
Output coupler
The partially transmitting resonator mirror through which the laser beam leaves the cavity.
Linewidth
The spectral width of a single-frequency laser's output, usually given in Hz, kHz or MHz at half maximum.
PM fiber
Polarization-maintaining fiber: fiber with built-in stress that keeps linearly polarized light in its launch orientation.