We describe NIST measurement services for the calibration of optical fiber power meters. To augment the absolute power measurements NIST provides nonlinearity, spectral responsivity, and uniformit.
Polarization-maintaining fibers work by intentionally introducing a systematic linear in the fiber, so that there are two well defined polarization modes which propagate along the fiber with very distinct phase velocities. The beat length Lb of such a fiber (for a particular wavelength) is the distance (typically a few millimeters) over which the wave in one mode will experience an additional delay of one wavelength compared to the other polarization mode. Thus a length Lb /2 of such fiber is equivalent to a.
A fiber Bragg grating (FBG) is a type of constructed in a short segment of that reflects particular of light and transmits all others. This is achieved by creating a periodic variation in the of the fiber core, which generates a wavelength-specific. Hence a fiber Bragg grating can be used as an inline to block certain wavelengths, can be use.