Single and multi-passband broadband Moire filters from dual exposure of uniform-period and chirped phase masks

In-fibre chirped Moire resonators are excellent filters in terms of fibre compatibility, and can potentially provide wide stopbands, narrow passbands and high rejection levels. This paper describes the realisation of chirped Moire in-fibre filters written using phase mask techniques. The filters described here were fabricated both from the dual exposure of a uniform-pitch phase mask followed by a third refractive index profiling scan and from the dual exposure of chirped phase masks. These techniques produce filters that replicate the broad bandwidths associated with holographic techniques and have the advantage of the good reproducibility associated with the use of phase masks.