1,721,000 research outputs found
High-power tunable erbium-doped fiber laser operating at 1.55µm
No full textThere is currently considerable interest in lasers based on the fiber waveguide geometry, and crystal fiber Nd:YAG lasers are now commercially available. We recently developed a new fiber laser technology based on doped glass which offers both a choice of dopant ions and the possibility of wavelength tunability. The Er3+-doped fiber laser is particularly interesting because its operational wavelength of 1.55µm coincides with the lowest loss region of silica optical fibres. Furthermore, the fiber can be used as a high-gain optical amplifier, which is compatible with quaternary (InGaAsP) devices
Dependence of fused taper couplers on external refractive index
No full textWe present the results of an experimental and theoretical investigation into the dependence of fused taper couplers on changes in the external refractive index. We show that it should be possible to fabricate long couplers which are insensitive to changes in the external refractive index
A diode pumped single-mode fibre laser
No full textFibre lasers present numerous advantages over other lasers not only in terms of low threshold, efficiency and low operating power but also with respect to their compatibility with standard single-mode fibres. Lasing action has been demonstrated in rare-earth doped silica single-mode fibres with both semiconductor laser and argon ion/dye laser pump sources. Semiconductor laser-diode pumping is highly convenient both in terms of cost and operational requirements. We describe here the characteristics of a single-mode Nd3+-doped fibre laser operating at 1.088µm. In particular results are presented for CW, Q-switched and mode-locked operation
High-gain rare-earth-doped fibre amplifier at 1.54µm
No full textOptical amplifiers are of interest as wideband in-line repeaters for telecommunications and as signal regenerators for a variety of sensor applications. Much current research has concentrated on semiconductor laser amplifiers which are difficult to splice to fiber systems. It is clear that an amplifier consisting of a special optical fiber which is compatible with telecommunication fiber would overcome this problem. This paper describes the first results of an optical fiber amplifier based on an Er3+-doped fiber which has a maximum gain at a wavelength of 1.536 µm. A single-pass gain of 26 dB and a maximum output of 13 dBm at 140 MHz has been demonstrated
Fabrication and characterisation of low-loss optical fibres containing rare-earth ions
No full textLow-loss fibers containing rare-earths have been produced with high absorption levels in the visible and near infrared regions. Although containing relatively large quantities of rare-earth impurity dopants, the fibers possess low-loss windows where the attenuation is similar to that observed in undoped fibers. This attribute makes the fibers attractive for use in long distributed sensors, as well as low-threshold fiber lasers. Fiber characteristics relevant to these two applications are uniformity of dopant incorporation, absorption and fluorescence spectra, and fluorescence lifetime. These measurements are presented, together with their respective temperature dependences. The fiber fabrication method is described and results given for Nd3+-, Er3+-, and Tb3+-doped fibers
Low-noise erbium-doped fibre amplifier operating at 1.54µm
No full textHigh gain amplification of up to 28 dB has been observed in a 3m-long erbium-doped fibre. The amplifier has a spectral bandwidth of greater than 300GHz in the region of 1.536µm and a measured sensitivity of -42dBm at a bit rate of 140 Mbit/s
Narrow-linewidth fiber laser operating at 1.55µm
No full textWe report the fabrication and operation of an Er3+-doped silica single-mode fiber laser operating at 1.55 µm and using a distributed fiber grating to provide feedback. The output bandwidth was measured as 0.04 nm, significantly narrower than the conventional cavity design. The laser had a threshold of 13 mW and a slope efficiency of 5%
Tunable single-mode fibre lasers
No full textTunable laser action has been obtained in Nd3+- and Er3+-doped single-mode fiber lasers. In the case of the Nd3+-doped fiber, an extensive tuning range of 80 nm has been achieved. Tunable CW lasing also has been observed for the first time in an Er3+-doped fiber laser, which has an overall tuning range of 25 nm in the region of λ = 1.54µm
A Pr<sup>3+</sup>-doped single-mode fibre laser
No full textThe rare-earth doped single-mode fibre laser has emerged as a new source of laser radiation in the near infrared region of the spectrum. Using an Ar+-ion, dye or semiconductor laser as a pump source, low threshold CW or pulsed operation is possible over a wide range of wavelengths. Low threshold CW laser emission is also possible on 3-level transitions at room temperature with no auxiliary cooling requirements. As an example, laser operation has been obtained at 1085nm on the 1G4 - 3H4 (groundstate) transition of Pr3+-ions in glass. The excitation source was a CW Rh6G dye laser operating at 590nm, although such was the absorption of the Pr3+-doped fibre that most of the Rh6G emission spectrum could be used for pumping. Using a cleaved fibre butted to two dielectric mirrors having high reflectivity at the lasing wavelength, CW threshold was found to occur for 10mW of absorbed power at 590m. Q-switching has been obtained using an intracavity acousto-optic modulator. In preliminary experiments using a non-optimised cavity, we have obtained pulses of 500ns duration and >1W peak power at a repetition rate of several kHz. Using a more efficient configuration, over an order of magnitude increase in peak power is anticipated. By replacing the output mirror with a diffraction grating blazed at 1µm, a 61m tuning range from 1048nm - 1109nm has been obtained. Using an alternative pump source, visible operation of this laser may be possible
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