title: Improving the spectral resolution of wedged etalons and linear variable filters with incidence angle.
abstract: Compact spectrometers fabricated by placing a wedged etalon or a linear variable filter in front of a linear photodiode array typically do not exhibit the spectral resolution of a parallel filter of the same finesse. A theoretical analysis of the beam emerging from a wedged etalon is shown to predict a comalike aberration, explaining the loss in resolution. This analysis also predicts a focused beam waist whose axial position depends on the incidence angle, indicating that resolution can be improved by placing this waist on the detector. These results are experimentally confirmed in a multicavity linear variable filter to achieve 0.09 nm spectral resolution at 1550 nm.
authors.affiliation: Department of Electrical and Computer Engineering, University of Colorado, Campus Box 425, Boulder, Colorado 80309, USA. mcleod@colorado.edu
authors.forename: Robert R
authors.initials: RR
authors.lastname: McLeod
authors.forename: Tokuyuki
authors.initials: T
authors.lastname: Honda