High reflectivity photorefractive Bragg gratings in germania-free optical fibres

We present the first report of Bragg gratings with reflectivities exceeding 99% written in germania-fibre optical fibres by UV exposure. This result has important implications for the production of ultrashort single-frequency fibre lasers

1.5µm Er³⁺:Yb³⁺ doped fibre DBF laser

We report the first DFB fiber laser. When pumped with a 980nm diode laser, the 2cm-long laser has an output power of 2mW at 1.534µm and a RIN of < -156dB/Hz

Photosensitivity in germanosilicate fibres: electronic change or physical change?

Presentation slides<br/

High reflectivity fibre gratings written by a single excimer laser pulse

We report fibre Bragg gratings with up to 65% reflectivity and bandwidths as small as 6 GHz written by a single 20 ns excimer laser pulse. Our results show that ~100% reflectivity single-pulse fibre gratings should soon be produced

Bragg gratings in germania-free optical fibres

To date, most research into Bragg fibre gratings has centred on conventional silica-germania optical fibre. Often, fibres co-doped with boron or containing high concentrations of germania are used in order to increase the achievable refractive index modulation

Er³⁺:Yb³⁺ co-coped fiber DFB laser

We report what is to our knowledge the first fiber distributed-feedback laser using a single Bragg grating at 1.5µm written directly into a 2-cm-long Er3+-doped fiber codoped with Yb3+. We obtained robust single-frequency operation by either using one end reflector or locally heating the center of the grating to create the necessary phase shift

Simple multiplexing scheme for fibre optic grating sensor network

A new approach for the interrogation of a large number of fiber-optic grating sensors is proposed and demonstrated for a small number of sensors in which signal recovery is achieved by matching a receiving grating to its corresponding sensor. This technique is demonstrated for both quasi-static and periodic measurands, and the resolution achieved for a single sensor-receiving grating pair for quasi-static strain of 4.12µε

Efficient diode-pumped single-frequency erbium:ytterbium fibre laser

We report a 7.6-mW single-frequency fiber laser operating at 1545 nm, using for the first time an Er3+:Yb3+ doped fiber and a fiber grating output coupler. The laser did not exhibit self-pulsation, which is a typical problem in short three-level fiber lasers, and had a relative intensity noise (RIN) level below -145.5 dB/Hz at frequencies above 10 MHz. The linewidth of the laser was limited by the relaxation oscillation sidebands in the optical spectrum and was typically less than 1 MHz. <br/

Grating-frustrated coupler: a novel channel-dropping filter in single-mode optical fibre

A low-insertion-loss, all-single-mode fiber, wavelength-division-multiplexing filter comprising a four-port polished coupler and a strong fiber grating is demonstrated. The device operated in a novel way by a process we call grating-frustrated directional coupling. A fiber grating, present in only one half of the coupler, frustrates the transference of power to the other half within a narrow wavelength range. The performance of a prototype device - a 1535-nm channel-dropping filter with 0.7-nm bandwidth, 70% peak transmission, and 13-dB isolation-shows great promise for wavelength-division-multiplexing and line-filtering applications