E.R. Taylor

Spectroscopy of Tm3+-doped tellurite glasses for 1470 nm fiber amplifier

Three thulium doped tellurite glass compositions have been investigated. The 1470 nm transition is radiative in these tellurite glasses and the radiative lifetimes are in the range of 350 to 470 µs. The 1470 nm fluorescence is broad with a full width at half maximum of 105 nm. Fibers have been drawn from these glasses with a loss of 0.7 dB/m at 1300 nm. A fiber with an OH fundamental absorption of 200 dB/m at 2.99 µm has an OH first overtone absorption of 0.3 dB/m at 1480 nm. The overlap between the thulium ion 1470 nm emission and the hydroxyl absorption depends on glass composition. Tellurite glasses can accept large concentrations of Tm3+ ions and, as long as the hydroxyl level can be kept low, the effect of concentration quenching can be minimized. Tm3+-doped tellurite glasses represent a viable alternative for the next generation of active components for S-band optical amplifiers. It can be pumped at 795 nm with an absorption of ~38 dB/km/ppm and codoped with Ho3+ to avoid self-termination of the 1470 nm transition. It can also be pumped at 1212 nm as efficiently as at 795 nm, but diodes are not yet available at this wavelength. Using available pump wavelengths of 1064 nm and 1047 nm will require fiber lengths 15 times longer than pumping at 1212 nm.

Quantum-efficiency of praseodymium doped Ga:La:S glass for 1.3 /spl mu/m optical fibre amplifiers

The gain of Pr/sup 3+/-doped ZBLAN fibre amplifiers is hindered by a poor quantum efficiency due mainly to a high rate of multiphonon decay. Sulphide-based glasses ameliorate this problem through a higher radiative rate and lower nonradiative rate. In this letter, Pr/sup 3+/-doped Ga:La:S glass has been evaluated spectroscopically in bulk and fibre form for its quantum-efficiency at 1.3 microns. Measurements reveal that absorption bands are broadened and the effective separation between the /sup 1/G/sub 4/ and /sup 3/F/sub 4/ level is reduced compared to ZBLAN glass. Judd-Ofelt analysis and the theory of multiphonon-decay now predict efficiencies of 80%, while 58% is measured. Oxide impurities are shown to play a key role in quenching of the radiative emission.<<ETX>>

Erbium doped nanostructured tin-silicate glass-ceramic composites

Er-doped tin–silicate glass–ceramic composites were synthesized from Si, Er and Sn molecular precursors by following a sol–gel method. Optical spectroscopy and electron microscopy showed that the resulting material is composed of an amorphous silica network that encloses submicrometric SnO2 crystalline clusters. Analysis of the luminescence properties shows that Er ions are, at least partially, trapped in the crystalline phase. Raman spectra show that nanostructured tin–silicate composites act as low phonon energy hosts for rare earth ions and are thus suitable for photonic applications.

The application of Ga:La:S-based glass for optical amplification at 1.3 μm

Abstract The optical properties of praseodymium-doped low-phonon-energy glasses have recently attracted considerable attention for their potential application as a 1.3 μm Pr +3 -doped optical fibre amplifier. Sulphide glasses based on Ga 2 S 3 and La 2 S 3 are amongst the lowest-phonon-energy glasses which are suitable for this application, with quantum efficiencies exceeding 50% currently measured on bulk samples in the laboratory. The purpose of this paper is to describe the thermal, optical and spectroscopic properties of Pr +3 -doped sulphide-based glasses, present the results of amplifier modelling using the measured cross-sections, and report the progress to date in achievement of a Pr +3 -doped sulphide-based fibre.

Short-pulse, high-power Q-switched fiber laser

A high-power, laser-diode-pumped, Q-switched fiber laser operating at 1.053 mu m which is suitable for use in time-multiplexed fiber sensor applications is described. The laser emits >1-kW pulses at 1.053 mu m with 2-ns duration at up to 1-kHz repetition rates for an adsorbed pump power of only 22 mW at 810 nm. Tunable Q-switched operation over a 40-nm wavelength range has also been demonstrated.<<ETX>>

Q-switched neodymium-doped phosphate glass fiber lasers

The operation of a short-pulse, Q-switched, neodymium-doped fiber laser operating at 1.054 mu m is described experimentally and theoretically. The laser is efficiently pumped with a single-stripe AlGaAs laser diode and emits >1 kW pulses. It is seen that due to high gain short pulses with high energy extraction efficiency can be obtained. The feature of broad emission lines associated with rare-earth-doped glasses is exploited to demonstrate tunable, Q-switched operation over a 40-nm tuning range. >

Study of UV written channels in lead silicate glasses

Abstract Light-induced refractive index change was investigated in two lead-silicate (SF57 and F2) glasses by irradiation using a pulsed 248 nm KrF excimer laser and a CW frequency doubled argon ion laser at 244 nm. UV–Vis spectra were recorded after each exposure to the excimer laser to study the change in absorption. The exposures were cumulative. The results showed that, with increasing number of pulses, there was an increase in the attenuation of the samples. Large photosensitivity was observed from direct 244 nm UV-written channels without the use of a phase mask. The refractive index change measured at 633 nm for SF57 glass was to 2.9×10−2 and a channel waveguide loss of 4.8 dB/cm and for F2 glass was to 7×10−3 and a loss of 5 dB/cm. The large refractive index changes measured here are achieved at the expense of large induced losses. The channel waveguides were thermally stable up to 300 °C.

Direct-UV-written buried channel waveguide lasers in direct-bonded intersubstrate ion-exchanged neodymium-doped germano-borosilicate glass

We report a technique for producing single-mode buried channel waveguide lasers in neodymium-doped SiO2:GeO2:B2O3:Na2O (SGBN) glass. Direct bonding forms the basis of this process, providing a buried waveguide layer in the photosensitive SGBN material into which channel confinement can be directly written with a focused UV beam. Characterization of a 7.5-mm-long device was performed using a Ti:Sapphire laser operating at 808 nm and the resultant 1059 nm channel waveguide laser output exhibited single-mode operation, milliwatt-order lasing thresholds, and propagation losses of <0.3 dB cm–1.

Growth and characterization of pulsed laser deposited lead germanate glass optical waveguides

AbstractLead germanate thin films have been grown on BK7 and silica substrates, using pulsed excimer laser deposition(PLD) at wavelengths of 193 and 248 nm, from a bulk lead germanate target under various partial pressures of oxygen.The films produced vary in colour from brown, through clear, to yellow, and a parametric study has been undertaken ofthe film properties as a function of the growth conditions. The measured losses of the lead germanate films grown onglass substrates varied from ˘2.5 to 7 dB cm y1 depending on the oxygen partial pressure used. O 1999 Elsevier ScienceB.V. All rights reserved. 1. IntroductionPulsed laser deposition (PLD) has been exten-sively researched within the past decade as acomparatively fast, easy, and flexible technique forgrowing thin films of a wide range of materials [1].Amorphous, polycrystalline, and single crystallayers are routinely grown, depending on experi-mental parameters that include target composi-tion, substrate temperature, target–substratedistance, and the presence of an ambient gas, of-ten oxygen, at moderately low partial pressures.Recent successes in crystalline growth by PLDhave permitted the demonstration of e†cient la-sing action in 2–10 lm thick layers of gadoliniumgallium garnet, GGG, grown on YAG [2,3], andalso Ti:sapphire, grown on undoped sapphire [4].The losses reported in Ref. [3], of 0.3–0.5dB cm

Spectroscopic properties of Nd3+ in fluoroaluminate glasses for an efficient 1.3 μm optical amplifier

Abstract In the majority of Nd 3+ -doped glasses the amplifier gain is shifted out of the second telecom window (1.3 μm) as a result of long-wavelength emission and signal excited-state absorption (ESA). In this paper we describe new fluoroaluminate glasses developed as hosts for the 1.3 μm Nd 3+ -doped fibre amplifier. Nd 3+ emission peaks at 1310–1317 nm were demonstrated in glasses. Gain in the 1310–1320 nm region was measured in unclad fibres, with evidence of reduced ESA. The paper also examines thermal and viscous properties of the core and cladding glasses for preform and fibre fabrication.