Holographic construction of 2-D arrays of UV intensity using additive source interference from multiple slab reflections J. Canning * , M.  Aslund Optical Fibre Technology Centre (OFTC), University of Sydney, Australian Photonics Cooperative Research Centre, 206, National Innovation Centre, ATP, Eveleigh, Sydney, NSW 1430, Australia Received 22 August 2001; received in revised form 2 November 2001; accepted 13 December 2001 Abstract Through the generation of multiple sources from the one coherent laser source combined with induced wavefront curvature, 2-D periodic fringe arrays of UV intensity are generated. These are suitable for holographic processing of materials and resists for numerous applications including possible 2-D photonic bandgap structures. Ó 2002 Published by Elsevier Science B.V. Pattern construction for resist processing and for other multi-dimensional applications generally involves the use of projection techniques where a laser passes through an optical mask onto the resist of choice [1]. Alternatively, the generation of 2-D arrays usually involves double exposure methods [2]. To obtain sub-micron features of reasonable quality projection imaging techniques become necessarily complex often requiring mul- tiple steps in the fabrication process. One means of overcoming this is to use arrays of polymeric microspheres transparent to the writing wave- length [3]. They act as individual microlenses capable of producing features of the order of 200 nm. In this way conventional photolithography is able to fabricate nearly arbitrary structures for creating masks for lithographic processing. In this Letter we suggest a simple holographic alternative based on a variation of the arrangements used in Young’s experiments [4], where two identical point sources interfere to create 1-D interference, and show how this can be utilised for the con- struction of patterned periodic fringes. This pro- cess then forms the basic unit upon which more complex patterns can be generated by cascading the system. The requirement of a mask is elimi- nated. The basis of the experiments rests on the prin- ciple that a glass slab can be used to generate a periodic distribution of optical intensity as light reflected from the front surface interferes with that reflected from the back surface. However, inter- ference can only arise under two conditions – the light source is of sufficient coherence and there is a non-planar wavefront. When these two conditions are met the separation of the front and back sur- faces of the slab becomes the aperture separation of two identical sources akin to that demonstrated 15 February 2002 Optics Communications 202 (2002) 271–275 www.elsevier.com/locate/optcom * Corresponding author. Fax: +61-2-9351-1910. E-mail address: j.canning@oftc.usyd.edu.au (J. Canning). 0030-4018/02/$ - see front matter Ó 2002 Published by Elsevier Science B.V. PII:S0030-4018(02)01094-5