Omnidirectional mirror coating design for infrared applications

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Omnidirectional mirror coating design for infrared applications
D. Lusk *, F. Placido
  s9 H% O! O0 pElectronic Engineering and Physics Division, Thin Film Centre, University of Paisley, Paisley PA1 2BE, Scotland, UK
! R9 Y" C! D4 CReceived 1 August 2003; received in revised form 1 April 2004; accepted 23 June 2005
8 U  K0 l% [$ @Available online 25 July 2005
Abstract
An omnidirectional mirror, with a reflectance (R) of 99.5% for all angles of incidence and both polarisations, was designed from quasiperiodic
dielectric stacks based on Fibonacci sequence (FS) by selecting appropriate materials for high and low refractive index layers. At
7 L3 V8 M( ]1 {! SR =99.5%, the initial omnidirectional spectral range was found to be from 1437 to 1618 nm, which covers completely the
telecommunications wavelength region and the S, C and L bands of the erbium doped fiber amplifier gain region. The individual layers
within the FS have the same physical thickness, thus having non quarter-wave optical thickness at the centre wavelength. Optimisation from
the initial design can expand the omnidirectional spectral region at R =99.5%, as well as show a higher value of R over the initial
% q$ T: |; z4 r' C& ]: Domnidirectional spectral range. Deposition and characterisation of the mirror coating have taken place using microwave assisted direct current
2 x# M6 W# V8 W. Nmagnetron sputtering and various characterisation techniques.
6 g  O7 k" T( [) j0 ?. RD 2005 Elsevier B.V. All rights reserved.
PACS: 68.65; 42.79.W; 42.15.E; 42.79.F
, x9 T$ `- G, |4 w! K% f2 a7 LKeywords: Multilayers; Optical coatings; Optical design; Reflectors

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