Abstract
The fabrication and characterisation of Long Period Gratings in fibre tapers is presented alongside supporting theory. The devices possess a high sensitivity to the index of aqueous solutions due to an observed spectral bifurcation effect.

Abstract
A new transmissive grating-based scanning delay-line for optical coherence tomography is proposed, with dispersion compensation capability. Compared to other spectral delay-lines, our implementation has less loss due to a halved number of diffraction grating reflections, and implements a walk off compensation scheme. The performance of the delay line is evaluated. The delay line transmissive geometry targets balance detection configurations. © 2005 SPIE and OSA.

Abstract
A novel Fourier domain fast scanning optical delay line is proposed in which the walk-off is eliminated by only two passes through a diffraction grating. Working in transmission, the novel delay line is ideal for balanced optical coherence tomography configurations with recirculation of the reference beam. We evaluate theoretically and experimentally its walk-off and dispersion compensation capabilities. (c) 2005 Optical Society of America

Abstract

Abstract

Abstract
We model the photocurrent of a depth-scan (A-scan) from an optical coherence tomography (OCT) system, using a linearly polarized thermal source, as an electronically filtered doubly-stochastic Poisson process, and we obtain its time-varying second-order statistics. We derive an expression for the instantaneous signal-to-noise ratio (SNR) of time-domain OCT which is more general than the previously reported time-averaged expressions. Unlike previous work, our analysis combines shot noise, due to detection of coherent light, and photon excess noise, due to fluctuations in the optical field, into a single noise source that we refer to as the photoelectron noise. Similar to previous results, our SNR is dominated by a term similar to shot-noise when the reference optical power is low and by a term similar to photon excess noise when the reference power is high. © 2005 SPIE and OSA.