Characterization of Short PM Raman Fiber Lasers with a Small Spectral Bandwidth

Engelbrecht, Rainer; Siekiera, A.; Bauer, Ralf; Neumann, R.; Schmauß, Bernhard

doi:10.1364/ofc.2011.omq2

Cited by 6 publications

(3 citation statements)

References 5 publications

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“…A slight bandwidth broadening is observed when comparing the forward output spectra with those of the backward spectra, and in the case of the high-NA fibre the SNR is also observed to be slightly reduced although it still remains above 50dB. The reason for the slight broadening and reduction of SNR we believe to be due to co-propagating nonlinear interplay between the forward signal and the residual pump power [8]. We hope to report further and give more detailed analysis on these observations in future publications.…”

Section: Resultsmentioning

confidence: 77%

“…Very different from their rare-earth doped counterparts, the operating wavelength of Raman fibre laser is only related to the pump wavelength and the Raman shift of the material used. They can therefore in principle be designed to oscillate at any desired wavelength ranging from the visible to the infrared region, pending only the availability of a suitable pump source [5][6][7][8]. This makes them very interesting for applications in telecommunications for example, where operation in extended wavelength bands currently is being considered and investigated to meet future capacity demands.…”

Section: Introductionmentioning

confidence: 99%

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Highly efficient Raman distributed feedback fibre lasers

2012

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We demonstrate highly efficient Raman distributed feedback (DFB) fibre lasers for the first time with up to 1.6 W of continuous wave (CW) output power. The DFB Bragg gratings are written directly into two types of commercially available passive germano-silica fibres. Two lasers of 30 cm length are pumped with up to 15 W of CW power at 1068 nm. The threshold power is ~2 W for a Raman-DFB (R-DFB) laser written in standard low-NA fibre, and only ~1 W for a laser written in a high-NA fibre, both of which oscillate in a narrow linewidth of <0.01 nm at ~1117 nm and ~1109 nm, respectively. The slope efficiencies are ~74% and ~93% with respect to absorbed pump power in the low-NA fibre and high-NA fibre respectively. Such high conversion efficiency suggests that very little energy is lost in the form of heat through inefficient energy transfer. Our results are supported by numerical simulations, and furthermore open up for the possibility of having narrow linewidth all-fibre laser sources in wavelength bands not traditionally covered by rare-earth doped silica fibres. Simulations also imply that this technology has the potential to produce even shorter R-DFB laser devices at the centimetre-level and with mW-level thresholds, if Bragg gratings formed in fibre materials with higher intrinsic Raman gain coefficient than silica are used. These materials include for example tellurite or chalcogenide glasses. Using glasses like these would also open up the possibility of having narrow linewidth fibre sources with DFB laser oscillating much further into the IR than what currently is possible with rare-earth doped silica glasses.

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Section: Resultsmentioning

confidence: 77%

Section: Introductionmentioning

confidence: 99%

Highly efficient Raman distributed feedback fibre lasers

2012

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“…A slight bandwidth broadening is observed when comparing the forward output spectra with those of the backward spectra, and in the case of the high-NA fibre the SNR is also observed to be slightly reduced although remains above 55dB. The reason for the slight broadening and reduction of SNR is believed to be due to co-propagating non-linear interplay between the forward signal and the residual pump power [13]. We hope to report further and give more detailed analysis on these observations in future publications.…”

Section: Experimental Setup and Resultsmentioning

confidence: 93%

High power, low threshold, Raman DFB fibre lasers

Shi

Alam

Ibsen

2011

2011 International Quantum Electronics Conference (IQEC) and Conference on Lasers and Electro-Optics (CLEO) Pacific Rim Incorpo

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Abstract:We demonstrate highly efficient Raman gain based distributed-feedback fibrelasers at ~1.11µm with up to 2W CW output-power with <0.01nm linewidth. The lasers are 30cm long and UV-written directly into two types of passive germanosilicate fibres. IntroductionAll-fibre rare-earth doped distributed feedback (DFB) lasers have attracted a lot of interest in recent years [1]. In addition to providing inherent fibre compatibility thereby ensuring low insertion loss, they exhibit numerous excellent optical properties. These include, outstanding beam quality, very low noise characteristics and extremely narrow linewidth, making them very useful sources in a number of applications in telecommunications, range-finding and LIDAR, and sensing [2][3][4]. It is a prerequisite of these sources to have high-concentration of rare-earth ions doping in the core of the fibre to facilitate high efficiency. High concentration of rare-earth ions can lead to problems with output power stability due to pair-ion quenching leading to inefficient pump energy transfer and excessive thermal loading. The operating wavelengths are also limited to regions characteristic to the specific rare-earth material used. A Raman gain based DFB fibre laser could overcome these limitations whilst maintaining all the attractive optical properties. This would therefore open up the prospect of generating high-power narrow linewidth low-noise oscillation at any desired wavelength ranging from the visible to the infrared region, pending only the availability of a suitable pump source [5][6]. Theoretical studies suggest that Raman DFB fibre lasers could be made comparatively efficient by employing π phase-shifted fibre Bragg gratings of only a few tens of centimetres of passive germanium doped silica fibres, and also that these should exhibit only watt-level threshold [7][8]. Only recently an experimental demonstration of Raman DFB fibre laser operating at 1.58µm was reported [9]. The threshold power required for laser oscillation in that case was extremely high at ~40W @1480nm, and only 65mW of output power was obtained at a pump power of 80W, corresponding to a conversion efficiency of only 0.08%.In this work, we experimentally demonstrate 30cm long Raman DFB (R-DFB) lasers in high-NA (0.35) and standard-NA (0.12) passive germanosilica (Ge/Si) fibres with threshold powers in the low watt regime. Up to 2W of CW output power is obtained for a pump power of only 13.7W with a threshold power of only ~1W. In addition to being the highest efficiency R-DFB laser demonstrated to date, it is also the highest ever reported output power from any DFB fibre laser, incl. rare-earth doped DFB fibre lasers, to the best of our knowledge. The highest achieved output power corresponds to a conversion efficiency of 14.6% which is ~182 times higher than the R-DFB reported in [9] The slope efficiencies with respect to the absorbed pump power are ~92% for the high-NA fibre, and ~74% for the low-NA fibre, respectively. The R-DFB fibre lasers oscillate with a linewidth of <0.0...

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Raman-Faserlaser

Engelbrecht

2014

Nichtlineare Faseroptik

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Characterization of Short PM Raman Fiber Lasers with a Small Spectral Bandwidth

Cited by 6 publications

References 5 publications

Highly efficient Raman distributed feedback fibre lasers

Highly efficient Raman distributed feedback fibre lasers

High power, low threshold, Raman DFB fibre lasers

Raman-Faserlaser

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