Robert J. Standish

Cladding pumped few-mode EDFA for mode division multiplexed transmission

We experimentally demonstrate a few-mode erbium doped fiber amplifier (FM-EDFA) supporting 6 spatial modes with a cladding pumped architecture. Average modal gains are measured to be >20dB between 1534nm-1565nm with a differential modal gain of ~3dB among the mode groups and noise figures of 6-7dB. The cladding pumped FM-EDFA offers a cost effective alternative to core-pumped variant as low cost, high power multimode pumps can be used, and offers performance, scalability and simplicity to FM-EDFA design.

First demonstration of cladding pumped few-moded EDFA for mode division multiplexed transmission

We report the first experimental demonstration of a cladding pumped FM-EDFA supporting 4 mode groups. The modal gains are measured to be >20dB between 1540nm-1570nm with a modal differential gain of ~4dB among the mode groups.

Q-switched neodymium-doped Y3Al5O12-based silica fiber laser

We present pulsed laser operation in a Nd-doped, Y3Al5O12-based silica fiber. The fiber was fabricated using the rod-in-tube technique with a Nd:YAG crystal rod as the core material and a silica tube for the cladding material. A spectroscopy study revealed that the core region had become amorphous in the process of fiber drawing. Q-switched pulsed laser operation was realized at a wavelength of 1058 nm when the fiber was cladding pumped at a wavelength of 808 nm. The laser delivered 38 μJ of energy in 65 ns pulses. The extracted energy was limited due to the multimodal operation of the fiber. Laser slope efficiency in continuous wave operation reached 52%. The spectroscopic properties of the fabricated fiber are discussed and compared to a Nd:YAG crystal and a Nd:Al-doped silica fiber.

Ytterbium doped nanostructured optical fibers for high power fiber lasers

With the breakthrough in ytterbium (Yb) doped fiber laser power scaling to kilowatt levels [1], the search for improved host glass properties has received much attention. A silica host, which is commonly used in high power fiber devices, has the advantage of being low-cost, reliable and able to sustain extremely high optical densities, as compared to other alternative glasses. However, silica is considered to be a poor host in terms of the level of Rare-earth(RE) that can be incorporated into it without the clustering effect of RE ions. This makes it difficult to achieve the high level of RE concentration in silica fibers, that is needed to shorten the device length of high power fiber lasers, which helps to suppress the non-linear effects (such as stimulated Raman and Brillouin scattering) in fibers. In this paper, we investigate Yb doped Y2O3 (or Y3Al6O12) nanoparticles in a silica rich matrix, as an alternative to the Yb in a ‘standard’, such as aluminium or phosphorous co-doped, silica host for use in high power fiber lasers. Y2O3 is a good host for RE incorporation, and efficient Yb:Y2O3 ceramic lasers have been reported in [2]. It is expected that Y2O3 nanoparticles within a silica host will improve the RE solubility in fibers.

Ytterbium doped nano-crystalline optical fiber for reduced photodarkening

We report suppression of photodarkening in Yb-doped nano-crystalline fibers in silica host. The photodarkening induced loss reduced by 20 times compared to Yb-doped aluminosilicate fibers. The laser efficiency of the nano-crystalline fiber was 79%.

5.4 W cladding-pumped Nd:YAG silica fiber laser

We report on the spectroscopy and laser characteristics of Nd-doped fiber, fabricated by rod-in-tube from Nd:YAG as a core material with silica cladding. A cladding-pumped CW laser operation at 1058nm with 52% slope-efficiency is demonstrated.

Polarization-maintaining ytterbium-doped fibre with an aluminosilicate inner-cladding fabricated using in-situ doping technique

The ytterbium-doped fibre laser (YDFL) has become the forerunner for high-power fibre lasers and amplifiers largely owing to the broad emission of Yb3+ ions (λ = 975 to 1200 nm) and their ability to be incorporated in a silica host in relatively high concentrations. Achieving multi-kilowatts of output power from a fibre has been made possible through improved fibre design and fabrication. In this paper we report on a robust polarization-maintaining (PM) YDFL with a unique aluminosilicate pedestal structure.

Modification of spectroscopic properties of bismuth doped silica fiber by post-fabrication process and different fabrication methods

The spectroscopic properties of pristine and H2-loaded MCVD based Bi-doped aluminosilicate fibers were investigated. Also, the properties of Bi-doped fiber, fabricated by powder-in-tube method, have been compared to MCVD based Bi fiber.