Fiber gratings operating in the transmission mode can provide high dispersion at wavelengths close to the Bragg resonance. When multiple gratings are cascaded for wavelength division multiplexing (WDM) applications, the net dispersion between the stop bands of any two consecutive gratings is significantly modified. We discuss the dispersion characteristics of such cascaded fiber gratings and pr...

We calculate the advances in near-infrared astronomy made possible through the use of fibre Bragg gratings to selectively remove hydroxyl emission lines from the night sky spectrum. Fibre Bragg gratings should remove OH lines at high resolution (R = 10, 000), with high suppression (30dB) whilst maintaining high throughput (≈ 90 per cent) between the lines. Devices currently under construction s...

Temporal spectral astronomy or time resolved astronomy is the study of astrophysical phenomena that show spectral variability on very short timescales. These timescales are often too short to be resolved by current astronomical equipment. The lack of detailed observations in this area keeps important theoretical descriptions of astronomical events unclear or incomplete. To resolve this, instrum...

We demonstrate a new type of on-chip Bragg grating designed to possess multiple stopbands at predetermined wavelengths. By employing sidewall modulation to control the full width half-maximum and extinction ratio, and through the incorporation of multiple spatial frequencies into the gratings' periodicities, we show that Bragg reflection can be achieved at particular wavelengths of interest wit...

We demonstrate the application of polymer planar Bragg gratings for multi-axial strain sensing and particularly highlight simultaneous 2D strain measurement. A polymer planar Bragg grating (PPBG) fabricated with a single writing step in bulk polymethylmethacrylate is used for measuring both tensile and compressive strain at various angles. It is shown that the sensitivity of the PPBG strongly d...

We consider mode coupling in multimode optical fibers using either two Bragg gratings or a Bragg grating and a long-period grating. We show that the magnitude of the band edge curvature can be controlled leading to a flat, quartic band-edge or to two band edges at distinct, nonequivalent k-values, allowing precise control of slow light propagation.

Effects of fabrication conditions on the double-peak structure observed in fiber Bragg gratings at harmonics of the Bragg wavelength were investigated, showing that slight variations in the alignment of the phase mask can affect the grating spectra significantly. A single peak occurs only when the incident beam direction is perfectly normal with respect to the fiber.

Optical waveguides that incorporate Bragg gratings have been written in bulk fused silica by using the femtosecond laser direct-write method and without the need for lithography or ion-beam techniques. A single manufacturing process is used to create waveguide-Bragg grating reflectors for operation in the C band.