Design principles of tunable interference light filters

Tunable interference light filters [1–5] hold a special place among the multitude of light filters because they combine the advantages of light filters and dispersing prisms (diffraction gratings). Those light filters can monochromatize light in broad light beams and can smoothly vary the wavelength. V. D. Kuznetsov Siberian Physicotechnical Institute at Tomsk State University. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 3, pp. 3–10, March, 1997.     

Principle for the design of interference light filters with two multilayers

There are many varieties of light filters consisting of a reflecting prism and nonhomogeneous multilayers. In the present article we will consider two types of such light filters, a light filter that is selective with respect to wavelength and angle of incidence of the light, and a light filter with elevated contrast that is wavelength tuned. Tomsk State University. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 10, pp. 49–53, October, 1998.     

Wide-band interference filters

Results of calculations are presented that demonstrate the possibility of constructing two-and threecomponent coatings for wide-band interference filters for the medium infrared spectral region with characteristics that could be realized earlier only in four-component interference coatings.     

Broadband interference filters

The characteristics of two-component broadband interference filtering coatings are calculated for the middle-infrared spectral range. Up to now, these characteristics have been obtained only for four-component interference coatings.     

High-frequency-pass metallic mesh interference filters

Summary High-efficiency metallic mesh high-frequency-pass interference filters have been designed and constructed for the wavenumber region 30100 cm^–1. Widebandpass filters have been fabricated using a combination of highpass and lowpass filters. The highpass filters have performed successfully at low temperatures.     

Low temperature narrow-bandpass interference filters

The use of metallic mesh to construct narrow-bandpass filters with halfwidths <5% which perform efficiently at 1.4 K is discussed. The technique uses thin metal foil annuli to determine the position of the Fabry-Perot maximum.     

Heat flow in interference filters

Presented here is a linear theory of heat conduction in an interference filter with an absorbing spacer. The source of heat is a Gaussian beam. The effects of thermal properties and construction of the system on the temperature are studied. A comparison with and conditions of validity of the single-film theory are also discussed.     

Very longwavelength lowpass interference filters

The extension of metallic mesh interference filter techniques to wavelengths longer than 2000 m is discussed. The problems associated with design considerations and removal of leaks is considered in some detail. Successful filters were produced with edges at 6.3 cm^–1 and 4.3 cm^–1. When used in series and with a specific optical system, good rejection of unwanted radiation was achieved.     

Multichannel silicon WDM ring filters fabricated with DUV lithography

We have fabricated 9-channel silicon wavelength-division-multiplexing (WDM) ring filters using 193 nm deep-ultraviolet (DUV) lithography and investigated the spectral properties of the ring filters by comparing the transmission spectra with and without an upper cladding. The average channel-spacing of the 9-channel WDM ring filter with a polymeric upper cladding is measured about 1.86 nm with the standard deviation of the channel-spacing about 0.34 nm. The channel crosstalk is about −30 dB, and the minimal drop loss is about 2 dB.     

Synthesis of contrast bandpass interference filters

A method is developed to design complex-period contrast bandpass interference filters with a band-width continuously varied in a wide range, which cannot be precisely formed by known classes of two-compoent multiple-half-wave passband systems.     

Hard coatings for optically bistable interference filters

We have fabricated optically bistable interference filters from layers of TiO₂ and SiO₂ vapour deposited on glass substrates. An experimental comparison with the more conventional ZnSe filters is presented. Our devices are superior in durability and switching contrast, equal in switching threshold, and slower in switching time.     

Suppression of background transmission of interference filters

The possibility of manufacturing interference filters with the transmission coefficient no less than 90% in fixed UV, visible or near IR spectral regions and completely opaque at longer wavelengths is shown. The operation of the filter is based on the method of residual rays. Angular dependences of the filter transmission bandshape on the parameters of multilayer coating, such as the thickness, refractive indices, and the number of the layers, are analyzed.     

Narrow-band holographic interference LiNbO3-based filters

New experimental data on antiparallel-beam holograms recorded in LiNbO₃, temperature fixation of the recorded holographic gratings, and the spectral characteristic of a narrow-band (0.01 nm) interference filter are reported. The effects of asymmetry in the diffraction efficiency and the emergence of satellites in the transmission spectrum of the filter are observed. These effects are explained using the birefringence properties of the crystal and the ability of holograms to transfer power between the beams in the course of recording.     

致冷多层干涉滤光片的光学特性

本文系统地研究了红外多层干涉滤光片的低温特性、并从薄膜的基本光学特性出发,推导了窄带滤光片、截止滤光片透射率与波长的温度效应.给出了截止滤光片截止波长的温度漂移公式.