Broadening of birefringent filter transmission bandwidth due to incident beam divergence

Abstract

Multistage birefringent filters have been employed for use as output frequency tuners in solid state and dye lasers. Our work with these devices has shown that the output pass band of the filter has a full width at half maximum (FWHM) on the order of 10Å, while theoretically one would expect it to be on the order of 1Å for a collimated beam. We have conducted a computer simulation study of the transmission characteristics of these filters and have found that a divergent beam will have a broader transmission curve than a nondivergent beam, and have determined the tolerance for divergence to produce an acceptably narrow pass band. We have found that a higher-order transverse mode pattern can produce a complicated transmission profile. We have also studied the effect of misalignment of individual stages in the filter to determine the tolerances in alignment of the stages. The temperature stability required to maintain the transmission peak wavelength of the filter within an allowable range has been obtained.