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The tuning performance of a liquid-crystal, electro-optically tunable, Lyot filter is described. This filter is widely tunable across the visible region up to a wavelength of approximately 630 nm and has very high performance characteristics that are preserved over the entire tuning range. These include a narrow passband of 0.1 nm, a large-aperture performance of at least 30 mm, a wide field of view of ?8.5 degrees , and the ability to be tuned to an accuracy that is one tenth of the linewidth of the passband. Possible applications for such a filter include remote sensing, multispectral sensing, and laser environmental and underwater monitoring.

A method for attenuating a laser beam based on the excitation of a surface plasmon is described. This attenuator is continuously variable, has a dynamic range of 10(2), has a spectral range covering the visible, does not steer the beam or distort its profile, and can handle powers of at least 1-W cw. Some preliminary results obtained on a crude prototype are presented; final device design and predicted performance are discussed.

Ultrahigh vacuum and molecular beam deposition techniques have been used to fabricate ZnSe interference filters. These demonstrate optical bistability with critical switching power being measured at five wavelengths between 521 and 676 nm. These filters demonstrate considerably improved long term operation stability over that offered by samples deposited using conventional thermal evaporation. Both dispersive and absorptive bistability could be demonstrated in the same sample.