A dual wavelength distributed-feedback fiber laser

Abstract

An approach to accessing air holes in a structured optical fiber with a distributed-feedback ͑DFB͒ laser based on higher order mode lasing is proposed and demonstrated. A narrow linewidth DFB fiber laser is fabricated in rare-earth-doped structured optical fiber. A higher order mode is shown to lase. Dual laser operation in both fundamental and higher order modes is also achieved. Numerical simulation of the mode profiles within the fiber using the adjustable boundary conditions-Fourier decomposition method supports the experimental results. Laser performance for each mode is characterized including imaging the emission of pump and lasing mode intensity profiles.

Measurement of modal dispersion by low coherence interferometer

“…It may be realized by PMD only when the polarization modes are transferred each to other during the wave's propagation along the fibre. However the broadening of the region may be caused not only by PMD, but also by existence of few modes, which phase constants differ in a small value to each other [9,10]. Application of a polarization measurement may help to decide which of these possibilities take place.…”

Fibre gratings and devices for sensors and lasers

“…Bottom shows the laser operates single polarisation. The measured linewidth by self-heterodyne is < 50 kHz [35].…”

“…Enabled grating writing in single-material structured optical fibres [17], as well as the first DBR and DFB photonic crystal fibre lasers with no GeO 2 but instead Al 2 O 3 in the core [33][34][35].…”

“…Two photon grating writing has enabled the first photonic crystal distributed Bragg reflector (DBR) and distributed feedback (DFB) fibre lasers to be fabricated [33][34][35]. The threshold for two photon grating writing in the core is significantly reduced when dopants such as aluminium are added to assist the suppression of clustering in rare earth doping.…”

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].…”