All-fibre photonic crystal distributed Bragg reflector (PC-DBR) fibre laser

Abstract

We describe an Er3+-doped aluminosilicate core photonic crystal fibre laser incorporating distributed Bragg reflectors written by two-photon 193nm irradiation through an optical phase mask as the feedback elements. The laser is diode pumped at 980nm and evidence of dual linewidth laser operation close to threshold is observed. However, at higher pumping levels gain competition preferentially selects one laser line.

Grating writing in structured optical fibers

“…This problem was firstly solved using two 193nm photon absorption directly into the band edge of the glass [21]. In aluminosilicate optical fiber, the threshold was significantly reduced whilst the total change was increased enabling the first structured fiber lasers made with gratings [22][23][24]. The two photon nature was confirmed experimentally [25,26].…”

A dual wavelength distributed-feedback fiber laser

“…The erbium-aluminosilicate core was fabricated by modified chemical vapor deposition ͑MCVD͒ 44,45 and solution doping process. The addition of aluminum is to reduce erbium clustering.…”

“…Figure 1 displays a scanning electron micrograph of the end face of the fiber with a diameter of 100 m. Additional information regarding the fabrication of the fiber can be found in Ref. 44.…”

“…44 Subsequent to this development, a distributed-feedback fiber laser was fabricated in the same erbium-doped air-silica structured fiber ͑ASSF͒. 45 The process of grating inscription required a high-intensity deep UV laser ͑Exciplex ArF 193 nm͒ since the photosensitivity of the fiber was low because we wanted to avoid both germanium and hydrogen sensitization.…”

Rotationally Variant Grating Writing in Photonic Crystal Fibres!

“…In spite of this scatter, Bragg grating writing has been demonstrated in various structured fibres including: (a) photonic crystal fibres with photosensitive germanosilicate cores, with and without hydrogen using single photon excitation [8][9][10][11]; (b) in Er 3+ -doped aluminosilicate core photonic crystal fibres using two-photon excitation [12,13]; and (c) in pure single material silica fibres also using two-photon excitation [14,15] and higher exponent femtosecond laser inscription [16]. However, the scatter of light incident from the side of the fibre does cause variation in the intensity within the fibre core during grating writing, both through incoherent scattering and coherent interference.…”