Tunable Pr/sup 3+/-doped silica-based fibre laser

The tunability of the Pr/sup 3+/-doped silica-based fibre laser has been investigated. A broad tuning range of 86 nm is obtained for the transition /sup 1/D/sub 2/-/sup 3/F/sub 3,4/ in the band centred at 1048 nm. Factors limiting tunability, and effects of host matrix and broadening mechanisms are discussed.<>     

Tunable Pr/sup 3+/-Yb/sup 3+/-doped all-fiber upconversion laser

Fiber lasers in the visible spectral range at 603 and 634 nm were demonstrated using upconversion in fluoride Pr/sup 3+/-Yb/sup 3+/-doped fibers and Bragg gratings photoinduced in germanosilicate fibers. Reliable fine tuning of the all-fiber laser over 6.9 at 603 nm has been demonstrated using high strength fiber Bragg gratings.     

85 W Tm/sup 3+/-doped silica fibre laser

An 85 W Tm/sup 3+/-doped silica fibre laser is presented. To the best of the authors' knowledge this is the highest output power achieved by pumping with 793 nm. The slope efficiency was 56%, the threshold 11 W and the output wavelength centred at 2.04 /spl mu/m. The high rate of cross relaxation in this laser provided a quantum efficiency of >130%.     

Multiwavelength diode-cladding-pumped Nd/sup 3+/-doped germano-aluminosilicate fiber laser

Simultaneous multiwavelength oscillation at 1060 and 1090 nm has been produced from a free-running Nd/sup 3+/-doped multicomponent silica fiber laser. As a result of co-doping with both Al/sub 2/O/sub 3/ and GeO/sub 2/, the Nd/sup 3+/ ions are situated at separate sites relating to either Al/sup 3+/-rich or Ge/sup 4+/-rich regions of the germano-aluminosilicate glass. The slope efficiency of the combined /spl sim/1-/spl mu/m output was /spl sim/52% (56%) with respect to the launched (absorbed) pump power. The 1060-nm emission reaches threshold first because of the greater number of Nd/sup 3+/ ions that are located at Al/sup 3+/-rich sites. On chopping the pump light the relaxation oscillations relating to the 1090-nm emission are antiphase with the oscillations observed with the 1060-nm emission. A degree of spectral overlap exists between the fluorescence emitted from Nd/sup 3+/ ions located at each site. Power equalization (to /spl sim/1 W each) of the 1060- and 1090-nm emissions was carried out by way of Raman amplification that occurred either internally or externally to the Nd/sup 3+/-doped silica fiber laser.     

High-power broadly tunable Ho/sup 3+/-doped silica fibre laser

Tuning of the 2.1 /spl mu/m Ho/sup 3+/-doped silica fibre laser is demonstrated for the first time. The /sup 5/I/sub 7//spl rarr//sup 5/I/sub 8/ transition provides tuning over 144 nm, from 2019 to 2163 nm, and a maximum pump-limited output power of 1.58 W at 2100 nm was produced.     

Semiconductor laser pumping of continuous-wave Pr/sup 3+/-doped ZBLAN fibre laser

Blue semiconductor laser pumped continuous-wave laser oscillation of a Pr-doped ZrF/sub 4/-BaF/sub 2/-LaF/sub 3/-AlF/sub 3/-NaF fibre in the red spectral range is reported for the first time. The pump power is provided by a frequency-doubled optically pumped semiconductor laser system. When pumped with 300 mW at a wavelength of 479.7 nm, the Pr/sup 3+/-laser emitted 94 mW of output power at a wavelength of 635 nm. Threshold pump power and slope efficiency with respect to the incident pump power were determined to be 49.7 mW and 41.5%, respectively.     

Controlled amplifier modelocked Er/sup 3+/ fibre ring laser

An erbium-doped fibre ring has been actively modelocked with an InGaAsP semiconductor amplifier employed as a modulator. Pulses having durations <4ps and peak powers of approximately 2 W around 1536 nm have been generated at a repetition frequency of 612 MHz by this new technique of controlled-amplifier modelocking (CAM).<>     

935nm Nd/sup 3+/ fibre laser incorporating tapered photonic bandgap fibre filter

An 8 cm length of photonic bandgap fibre was tapered in the middle to narrow the transmission windows. The tapered fibre was incorporated into a neodymium fibre laser system, in which it suppressed the strong gain peaks at 907 and 1080 nm and ensured lasing at 935 nm     

Nd/sup 3+/-doped single mode fibre superfluorescent source with 320 mW output power

A diode array pumped Nd/sup 3+/-doped superfluorescent fibre source with 320 mW output power and a 4.6 nm FWHM bandwidth centred at 1058 mu m is reported. The device is prevented from lasing off reflected light from Rayleigh backscatter by seeding an Nd/sup 3+/-doped fibre amplifier with a primary superfluorescent source of moderate power.<>     

Temperature insensitive Er/sup 3+/-doped optical fibre amplifiers

Temperature dependence of the gain at 1.536 mu m in Er/sup 3+/-doped fibre are reported for 0.98 and 1.48 mu m pumping. The fibre lengths at which gain is temperature insensitive are found for both pump wavelengths. The temperature insensitive gain characteristics for 0.98 mu m and 1.48 mu m pumping are demonstrated to fibres tuned to their temperature insensitive lengths.<>     

210 mW 2.84 /spl mu/m Ho/sup 3+/, Pr/sup 3+/-doped fluoride fibre laser

210 mW of unsaturated continuous-wave output from a Ho/sup 3+/, Pr/sup 3+/-doped fluoride fibre laser is demonstrated using the /spl sim/1100 nm output from a free-running diode-cladding-pumped Yb/sup 3+/-doped silica fibre laser as the pump source. A slope efficiency of 3.2% and an output wavelength of 2.84 /spl mu/m are obtained.     

Pr/sup 3+/-doped fluoride single-mode fiber laser

Laser oscillation at 1.312 mu m was achieved using a Pr/sup 3+/-doped fluoride single-mode fiber laser pumped at 1.017 mu m. The operation of a rare-earth-doped fiber laser at 1.31 mu m, which is one of the central wavelengths in conventional optical telecommunication trunk line systems, was demonstrated for the first time using Pr/sup 3+/ ion as an active ion. The laser cavity consists of a mirror and a cleaved fiber facet used as an output mirror. The maximum output power, threshold pump, and slope efficiency are 26 mW, 370 mW, and 9.86%, respectively.<>     

Noise characteristics of Pr/sup 3+/-doped fluoride fibre amplifier

The noise characteristics of a Pr/sup 3+/-doped fluoride fibre amplifier (PDFFA) are reported for the first time. Using an amplifier with a 20 dB gain, a noise figure of 3.2 dB is obtained at a wavelength of 1.31 mu m at an amplified output signal power between -18 and -2 dBm. However, it is observed that the noise figure increases when the signal wavelength is above 1.32 mu m.<>     

Highly efficient 980 nm operation of a Yb/sup 3+/-doped silica fibre laser

Efficient operation of a Yb/sup 3+/-doped silica-fibre laser at 980 nm is reported. When pumped with a dye laser at 890 nm, and with a symmetrical cavity, a lasing threshold of 17 mW launched power and a single-ended slope efficiency of nearly 40% against launched pump power has been achieved.<>     

High-power multiwavelength Er/sup 3+/-Yb/sup 3+/ codoped double-cladding fiber ring laser

A high-power simultaneous multiwavelength lasing in an Er/sup 3+/-Yb/sup 3+/ codoped double-cladding fiber (EYCDF) ring laser is demonstrated based on a wavelength-dependent filter through spatial mode beating within the multimode fiber section. We have investigated the relationship between the lasing wavelengths and the length of the EYCDFs. The experimental results indicate that both the number of lasing wavelength lines and the spacing between two adjacent lasing lines can be controlled by the changes of the lasing light polarization states.     

Singly Ho/sup 3+/-doped fluoride fibre laser operating at 2.92 /spl mu/m

A singly Ho/sup 3+/-doped fluoride fibre laser that uses energy transfer upconversion to maintain the population inversion has produced 340 mW at 2.92 /spl mu/m. The /spl sim/1100 nm output from a diode-cladding-pumped Yb/sup 3+/-doped silica fibre laser was used as the pump source and a maximum slope efficiency of 5% was obtained.     

High repetition rate passively Q-switched Nd/sup 3+/:Cr/sup 4+/ all-fibre laser

A passively Q-switched fibre laser comprising an Nd/sup 3+/-doped gain fibre spliced to a new Cr/sup 4+/-doped saturable absorber fibre delivers 0.3 nm-bandwidth continuous pulsed laser beam at 1084 nm, with 38 to 84 kHz repetition rate, and 3.0 to 6.4 /spl mu/s pulse duration.     

Amplification in Pr/sup 3+/-doped fluorozirconate optical fibre at 632.8 nm

Amplification in Pr/sup 3+/-doped fluorozirconate optical fibre is reported at the 632.8 nm He-Ne wavelength. Gross gains up to 11 dB have been achieved in a 1.4 m length using a launched pump power of 315 mW at 476.5 nm. Measurements of extinction at pump and signal wavelengths indicate that significantly improved performance can be expected using a much shorter length of fibre.<>     

Simultaneous operation of a Raman fiber amplifier and laser pumped by a dual-wavelength Nd/sup 3+/-doped fiber laser

This paper presents an experimental study on the dynamics of Raman fiber lasers that use highly GeO/sub 2/-doped fibers as an active medium and a dual-wavelength (1060 and 1090 nm) Nd/sup 3+/-doped fiber laser as a pump source. The 1090-nm pump wavelength is located within the SiO/sub 2/ Raman gain spectrum relating to the 1060-nm pump wavelength, and competition is observed between Raman amplification of the 1090-nm emission with the 1060-nm emission used as the pump source and Raman lasing, which is independent of the 1090-nm amplification and which is also uses the 1060-nm emission as the pump source. Several pump configurations have been demonstrated to generate specific Stokes emissions generated through Raman lasing or amplification. Changing the gain-to-loss ratio by introducing intracavity loss of Raman emissions or increasing the Raman fiber length within each configuration can force either Raman amplification or lasing to dominate. The maximum slope efficiency as a function of the launched pump power was /spl sim/55% with a total output power of 1.6 W produced. A red shift of both the pump and the Stokes wavelengths is experimentally observed when the launched diode pump power is scaled up.     

Multiple-wavelength up-conversion laser in Tm/sup 3+/-doped ZBLAN glass fiber

In this letter, we report on a multiple-wavelength up-conversion laser in Tm/sup 3+/-doped ZrF/sub 4/--BaF/sub 2/--LaF/sub 3/--AlF/sub 3/--NaF glass fiber pumped by an 1120-nm fiber laser. Single-wavelength, two-wavelength, and three-wavelength up-conversion lasers can be obtained by adjusting the distance between the coupler mirror and the fiber end, which is attributed to the frequency-filter effect in the etalon composed of the coupler mirror and the fiber end. The effects of the pump power on the performance of dual-wavelength laser were also discussed.