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We believe that days of diode pumped Nd:YAGs and Argon-ions are over. Why? Because of
High Power Fibre Sources in the Visible and UV using Periodically Poled Nonlinear Materials
6W average power, PPKTP based green source and 60mw average power, PPLT based, UV sources
In our research, we focus on development of high power Er/Yb based fiber sources in combination with novel Periodically Poled materials. The aim is to achieve highly efficient optical frequency conversion from Ytterbium , Erbium and Raman windows of amplification into the whole spectral range of wavelengths with particular emphasis on the Visible and Ultra-Violet.
Wavelengths Accessible using Yb/Er Fibre Sources and periodically poled crystals
We develope and use fibre sources based on master-oscillator-fibre-amplifiers (MOPFA) configuration with variable spectral and temporal characteristics and high peak powers which are required for efficient nonlinear optical frequency conversion in periodically poled crystals.
The Yb and Er fibre amplifiers we use utilise cladding pumped geometries and multimode coupler technology. Their benefits are compact format, diffraction limited fibre delivered beams, high wall plug efficiency (15-20%). Today, Yb (1.01 - 1.1 mm ) 50W and Yb-Er ( 1.53 - 1.6 mm) 10W+ amplifiers are commercially available.
Experimental setup using MOPFA configuration. PC - polarisation controller, GL- GRIN lens.
On the material's side, our research covers a wide range of ferroelectric materials which allow efficient poling such as KTP, LiNbO3, LiTaO3, RTA. Through the poling, the higher nonlinear index of the bulk material, d33, can be employed for second order non-linear frequency conversion. Poling period, absorbtion edge and effective nonlinearity value are the factors which influence the choice of the periodically poled material for a given optical conversion technique and fundamental wavelength of the fibre source.The optical damage threshold, photorefraction, grey tracking and thermal loading effects in periodically poled materials are of our prime research interest as these become crucial issues in stability and application areas involving high power fibre sources.
Recently, we proposed, developed and successfully demonstrated:
Ytterbium Based Fibre Sources
Erbium Based Fibre Sources:
Raman Optical Frequency Conversion in the Visible:
