Athermal tunable filter with wavelength and intensity responses based on volume phase hologram

摘要

The present invention relates to an athermal tunable filter in which the wavelength and intensity responses of the filter can be independently tuned by moving the location of the filter. The filter is fabricated by recording multiple volume phase holographic gratings in highly stable photosensitive glasses (e.g. Ge-doped fused silica optic fiber preforms). The athermal operation is realized by an innovative design, in which the shift of the effective grating period induced by the thermal-optic effect is automatically compensated by the shift of incident and output beam angles. In addition, by recording the gratings in selected areas, the intensity response of the filter can also be independently tuned. This innovative tunable filter has many applications including, compact reconfigurable optical add/drop multiplexers (ROADM), dynamic gain equalizers, optical performance monitor (OPM), tunable chromatic dispersion compensation module, WDM combiner, tunable wavelength stabilizer, tunable lasers, and compact spectroscopy.