[Show abstract][Hide abstract] ABSTRACT: In the last few years, fibre lasers have established themselves as the preferred laser source in many applications. The combination of small size, maintenance-free operation, thermal and electrical efficiency combined with outstanding (diffraction- limited) beam quality have made the fibre laser an attractive alternative to more established technologies. In fact, in some processes the fiber laser is the enabling technology. Unique among high power lasers, the fiber laser is monolithic, the light being entirely confined to the fiber core. This gives immunity to thermal distortion of the beam, almost instant startup, very high stability and protection from the environment. Maintenance is minimal, since no realignment or cleaning of components is necessary. In this review paper, we will:
[Show abstract][Hide abstract] ABSTRACT: We have demonstrated a highly-efficient cladding-pumped ytterbium-doped fiber laser generating 1.36 kW of continuous-wave output power at 1.1 mum with 83% slope efficiency and near diffraction-limited beam quality. The laser was end-pumped through both fiber ends and showed no evidence of roll-over even at the highest output power, which was limited only by available pump power.
[Show abstract][Hide abstract] ABSTRACT: A cladding-pumped ytterbium-doped fibre laser, generating up to 610 W of continuous-wave output power at 1.1 μm with slope efficiency of 80% and near diffraction-limited beam quality (M<sup>2</sup>=1.3) is reported. No undesirable roll-over was observed in output power with increasing pump power.
Full-text · Article · Dec 2004 · Electronics Letters
[Show abstract][Hide abstract] ABSTRACT: Three-level operation of a fiber distributed feedback (DFB) laser operating around 980 nm is demonstrated for the first time. The ytterbium-doped DFB laser shows a maximum slope efficiency of 61% and output power of 38.2 mW under a launched single-mode pump power of 150 mW at 910 nm. The efficiency of lasers with different coupling strengths and at different pump wavelengths is also investigated.
[Show abstract][Hide abstract] ABSTRACT: We present a narrow linewidth cladding-pumped erbium:ytterbium co-doped large-core fiber laser with output power up to 70 W at 1560 nm, and tunable from 1550 to 1602 nm using a narrow-band fiber Bragg grating.
[Show abstract][Hide abstract] ABSTRACT: We propose a novel design of highly birefringent optical fiber composed of a central elliptical air hole, a circumferential elliptical ring core, and a circular cladding. The proposed waveguide structure is predicted to produce a linear birefringence higher by an order of magnitude than the solid elliptical core fiber. The large index contrast between the central air and germanosilica elliptical ring core is mainly attributed to the high birefringence and its characteristics are theoretically analyzed in terms of its waveguide parameters.
[Show abstract][Hide abstract] ABSTRACT: We propose and analyze a novel design of high birefringence fiber incorporating an elliptical air hole in the core. Compared to solid elliptical core fibers, several times higher birefringence is achieved with a sub-wavelength-sized hole.
[Show abstract][Hide abstract] ABSTRACT: We report highly efficient cladding-pumped ytterbium-doped fiber lasers in various configurations, generating up to 1 kW of continuous-wave output power at 1.1 mum with an 80% slope efficiency and a good beam quality
[Show abstract][Hide abstract] ABSTRACT: A ytterbium-doped fibre laser with up to 1 kW of continuous-wave output power at 1.09 μm with a slope efficiency of 80% and a good beam quality (M<sup>2</sup>=3.4) is reported. The fibre was pumped by two diode-stack sources launched through opposite ends. No undesirable roll-over was observed in output power with increasing pump power.
No preview · Article · May 2004 · Electronics Letters
[Show abstract][Hide abstract] ABSTRACT: A three-level fiber DFB-laser operating at 977 nm is demonstrated for the first time using a 910 nm pump diode. The fiber DFB laser shows 17.5 mW output power under a launching power of 113 mW.
[Show abstract][Hide abstract] ABSTRACT: Bragg gratings in optical fibre waveguides have now been around for 25 years and they were soon after being realised, identified as one of the most significant fibre-optic inventions with potentials in a wide variety of areas among telecommunications equivalent to that of the erbium doped fibre amplifier. In this paper recent advances in the areas of Bragg gratings, fibre-DFB lasers and high-power fibre-lasers are reviewed and discussed their applications in optical systems.
[Show abstract][Hide abstract] ABSTRACT: A single-frequency, single-mode, plane-polarized ytterbiumdoped all-fiber master-oscillator - power amplifier source at 1060 um generated 264 W of cw output $wer (pump-power limited) The li-stage amplifier operated with a high gain of 19 dB and a high conversion efficiency of 68%. 02004 Optical Society of America OCIS codes: (140.3510) Lasea, fiber; (060.2420) Fiben, polarization-maintaining Cladding-pumped ytterbium-doped fiber sources have been power-scaled to the kW-level with good or even diffraction-limited bean quality (I - 31. Furthermore several options have been investigated for polarization-maintaining (PM) fibers for single-polarization operation, resulting in powers of up to -300 W with good polarization-extinction ratio (PER) (3 - SI. Technological improvements in diode pump sources, fiber fabrication and gain medium. as well as fiber design, device confguratioq and heat-sinking. have enabled this spectacular progress. Applications such as coherent combination (6) and gravitational wave detection (7) in addition require single-frequency snurces with narrow linewidth However, stimulated Brillonin scattering (SBS) has limited the power from single-frequency fiber sources to -100 W (SI. While short fihers and large cores mitigate SBS, further power-scaling of single-frequency fiber sources has remained uncertain. We present here a single-frequency, single-mode, planepolarized ytterbium-doped fiber master-oscillator - power amplifier (MOPA) source with 264 W of cw output power, limited only by available pump power. Figure 1 depicts the MOPA. A 1060 nm, 80 mW, planepolarized Yhdoped fiber DFB laser (master oscillator) fmm Southampton Photonics, Inc. (SPI) was followed by four Ybdoped fiber amplifiers. The DFB laser and the final amplifier are tlic key components, while three standard non-PM amplifiers (SPI) were used in intermediate stages. The DFE! laser linewidth was < 60 kHz (resolution-limited). The final-stage amplifier comprised a 7 m long double-clad birefringent Yb-doped fiber fabricated by SPI. It had a 25 im diameter, 0.06 NA core. The inner cladding was D-shaped with a 380 iin diameter. A low-index polymer coating provided a nominal inner-cladding NA of 0.48. The fiber incorporated a pair of borosilicate stress kds which, in this design, leads to a core birefringence of -2~10~. Up to 390 W of pump power was launched into the signal output end of the fiber from a 975 nm diode pump soum. The pump absorption was 2 dB/m. A dichroic mirror separated the signal output and pump beam paths. Both fiber ends were angle-cleaved. With proper adjustment of the polarization from the non-PM amplifier chaiq 3 W of signal input power could be launched into the final-stage amplifer through a polarizing free-space isolator. The polarization was aligned on a birefringence-axis of the final-stage fiber. Figure 2 shows the MOPA power characteristics as the pump power of the final-stage amplifier was varied. Other components operated at their maximum power (see Fig. I). The maximum output power (261 W) was limited by available pump power, and there was no sign of any roll-over. The power conversion efficiency was 68% at maximum power and the slope efficiency was 72% with respect to launched pump power. The linewidth of the ou ut was still below the 60 kHz resolution limit (Fig. 2). The PER was 16 dB, and the beam quality factor (M ) was better than 1.1. With textbook values for the Brillouin gain coefficient (SxIO-" m/W), we estimate the Brillouin gain to -200 dB in the last-stage amplifier. Tlus should lead to substantial SBS, hut &ere was no sign of this. We conclude that our simple estimate exaggerates the Brillonin gain. Temperature and fiber compositional variations, which broaden the Brillouin gain, may be the explanation. In summary, we have demonstrated a 1060 um single-frequency fiber MOPA source with 264 W of output power, limited by available pump power. The polarization extinction ratio was 16 dB and the M2- 'p
[Show abstract][Hide abstract] ABSTRACT: We review the recent rapid progress in the area of high-power fibre lasers and amplifiers in 1.1 and 1.5 μm spectral ranges. This progress is represented by a 610 W Yb-doped fibre laser, for example.
[Show abstract][Hide abstract] ABSTRACT: The performance of an L-band fibre-DFB-laser is characterised when pumped at 1534nm and 980nm. >10mW of power is demonstrated at 1618nm under 980nm pumping. The thermally induced wavelength-shift is reduced by >10 times under 1534nm pumping.
[Show abstract][Hide abstract] ABSTRACT: Fiber lasers were demonstrated as early as in the 1960s, but they were hampered by the need for laser pumping for efficient operation. The mid 1980s saw the realization of rare-earth doped single-mode high silica fibers with low loss. In a symbiotic pairing with advances in semiconductor pump lasers, a rapid development of active fiber devices ensued. This led to the erbium-doped fiber amplifier (EDFA), which has revolutionized optical telecommunications.
[Show abstract][Hide abstract] ABSTRACT: A 50-GHz grid fiber distributed feedback laser wavelength-division-multiplexing transmitter source is demonstrated pumped by a single continuous-wave Yb-fiber laser source at 977 nm. Up to 21 mW of output power is achieved per channel with maintenance of key operational parameters. The performance of this single Yb-fiber laser pump configuration is also compared with that of a semiconductor pump configuration which shows no degradation for all the important parameters.
[Show abstract][Hide abstract] ABSTRACT: The optical output from an all-fibre DFB-laser compression tuned over most of the C-band is analysed and characterised. The single-polarisation and line-width performance of the device is maintained across the full tuning range.
[Show abstract][Hide abstract] ABSTRACT: A single-polarised D-shaped fibre DFB laser with keyed axis output is demonstrated. The laser shows an output power of 3.8 dBm and strong axis alignment when spliced to a polarisation maintaining fibre.
No preview · Article · Dec 2002 · Electronics Letters
[Show abstract][Hide abstract] ABSTRACT: A tunable package for fibre Bragg gratings is proposed and demonstrated. Reliable and stable axial compression is achieved using this with up to 29nm of continuous tuning with a precise and repeatable tuning algorithm.
[Show abstract][Hide abstract] ABSTRACT: A 50GHz fibre-DFB laser transmitter source is demonstrated pumped by a CW fibre laser source at 977nm. Up to 9dBm of power is achieved per fibre DFB-laser with maintenance of all key operational parameters.