ATHERMAL TUNABLE FILTERS WITH WAVELENGTH AND INTENSITY RESPONSES BASED ON VOLUME PHASE HOLOGRAM

摘要

The present invention relates to an athermal tunable filter in which thewavelength and intensity responses of the filter can be independently tuned bymoving the location of the filter. The filter is fabricated by recordingmultiplevolume phase holographic gratings in highly stable photosensitive glasses(e.g.Ge-doped fused silica optic fiber preforms). The athermal operation isrealizedby an innovative design, in which the shift of the effective grating periodinducedby the thermal-optic effect is automatically compensated by the shift ofincidentand output beam angles. In addition, by recording the gratings in selectedareas, the intensity response of the filter can also be independently tuned.Thisinnovative tunable filter has many applications including, compactreconfigurable optical add/drop multiplexers (ROADM), dynamic gainequalizers, optical performance monitor (OPM), tunable chromatic dispersioncompensation module, WDM combiner, tunable wavelength stabilizer, tunablelasers, and compact spectroscopy.