A new mixed birefringent filter

Abstract: A NaCl∶OH ring color center laser, tunable from 1.49–1.70 μm with a two plate birefringent filter has been realized, which yields 1.5 W output power at 6 W Nd-YAG input pump power. Calculations of the spectral net gain including the homogeneously broadened gain profile, the birefringent transmission characteristics, and the mirror reflectivities are presented and compared with the experimental results.

Abstract: This is the first experimental demonstration of the Solc filter action in bulk composed of a slab of an optically active single crystal of left-handed quartz and a slab of right-handed quartz. The total birefringence of slabs and multiple total internal reflections from their external surfaces are used to form retardance of elements of a classic filter. The optical rotation difference of left-handed and right-handed quartz plates is used for mutual orientation of the elements. Precision of plate production ensures compliance with the technological requirements to filter parameters. Spectral transmission curves of the five-element filter, data of contrast measurement, full width at half maximum and angular field of view are presented. The filter potential is discussed.

Abstract: In this article, the transmission characteristics of a composite birefringent filter have been studied. The filter consists of a combination of two sets of cascaded systems of retarders with a polarizer in between the two sets, and a linear polarizer at each end. Each of the sets of retarders is essentially a cascaded fan-type Solc filter. The retardation introduced by retarders of the first set is different from the retardation introduced by the retarders forming the second set. Our theoretical study reveals that the system proposed has better filtering characteristics compared to that of a standard Solc filter.

Abstract: In this communication, the construction and transmission characteristics of a narrow band-pass birefringent filter have been investigated. The filter is formed by a combination of two sets of retarders with a polariser in between, and two linear polarisers placed at the two extreme ends. The sets of retarders are chosen to be a cascaded fan-type Solc filter having two different kinds of retardations, resulting in filtering characteristics better than those birefringent filters proposed for the visible range. The performance of this proposed filter is better in terms of effective suppression of side peak amplitudes as well as reduction of bandwidth with less number of waveplates. This birefringent filter can be used inside a linear resonator.

Abstract: Optical resonators containing tilted birefringent plates as tuning devices have been studied on the assumption that the resonator modes are eigenfunctions of an assembly of retardation plates interspersed with partial polarizers. The bandwidth is narrower than that of an equivalent filter using perfect polarizers, but the extinction coefficient does not go to zero. Stacks of plates whose thicknesses are in integer ratios have bandwidths much narrower than those of equivalent Lyot filters, but the secondary maxima do not correspond to those of Lyot filters. Application to the organic-dye laser is discussed. A device analogous to the Solc filter is also considered.

Abstract: The use of a tilted solid etalon inside the resonator of a gas laser, for the purpose of obtaining a tunable single mode output from the laser, is described and analyzed. This technique is illustrated by single mode spectra and gain profiles obtained with various argon ion laser transitions.

Abstract: A tunable dye laser with narrow‐banded spectral output in the order of 0.01 A or smaller is described. This narrow spectral output is obtained by means of a birefringent filter (Lyot filter) which was inserted into the laser cavity. The properties of this laser setup have been investigated and are described.

Abstract: Polarization interference filters are described which can have a pass band ranging from a fraction of an angstrom to several hundred angstroms in width. The pass band can be shifted to any desired region of the spectrum. These tunable filters are based on the fixed filters discussed by Lyot and Evans. The transmission band is formed by the superposition of the polarized channel spectra, produced by x-cut plates of quartz or other birefringent media placed between parallel polarizers. The birefringent plates have thicknesses in the ratio 1:2:4 etc. The tuning is accomplished by changing the retardation of successive elements so that transmission maxima in the various channel spectra coincide at the desired wave-length. The retardation change can be made mechanically, for example, by stretching supplemental plastic sheets in series with the filter elements, or can be made electrically by using Kerr cells or crystals with high electro-optic coefficients, such as ammonium dihydrogen phosphate. The additional retardation never has to exceed a full wave at the wave-length of peak transmission. The measured transmission of an experimental filter is shown. The electrical tuning method is particularly adapted to cathode-ray oscillograph presentation of spectra. The filter also has possible application in color reproduction and colorimetry. With a pass band of a half-angstrom line of sight motion of solar prominences could be determined by the use of the Doppler shift of the prominence radiation.

Abstract: In this article, the transmission characteristics of new mixed birefringent filter have been studied. The term ‘mixed’ is used because in this filter both linear and circular birefringence are utilized for shaping its transmission function. The filter has a so called ‘lossless core’, consisting of alternate rotators and retarders, and two linear polarisers at the two ends. Because of the similarity of the proposed mixed birefringent filter with the fan type Solc filter, it has been given the name ‘Mixed Solc Birefringent Filter’ (MSBF).