Diode seeded parametric amplifier pumped by a picosecond all-fibre system

Abstract

Several recent advances in fibre source development have greatly increased the output powers and energies available from compact fibre laser systems,[1,2,3]. Suitable levels are now achievable for pumping of parametric devices that use highly nonlinear materials such as periodically poled lithium niobate (PPLN). This powerful combination of fibre sources and PPLN promises a whole range of efficient, widely tunable, practical, all solid state optical sources and devices [ 4 ,5, 6, 7]. Fibre-laser-pumped optical parametric amplifiers ( 0 P As) constitute one such nonlinear device type offering gains in excess of 80d.B. With such high gains OP As can be used to amplify parametric noise to appreciable power levels so as to efficiently provide high power, broadband parametric fluorescence. An OPA operated in such a fashion is called an Optical Parametric Generator (OPG), [8]. A fibre-laser-pumped OPG has already been demonstrated by Galvanauskas et al. [7] who used a femtosecond erbium-fibre-based chirped based amplification (CPA) system with bulk gratings combined with PPLN to obtain broadband emission on a femtosecond timescale tunable in the wavelength range 1.05-2.9µm. However, due to the noise initiated nature of the process and broad gain bandwidth the generated pulses were far from transform-limited. The same authors also demonstrated a high gain OPA, using millijoule energy pump pulses from a bulk amplifier and a chirped nanosecond pulsed seed [9].
In the following we describe PPLN-based OPA (and OPG) experiments performed using a picosecond all­fibre CPA system as a pump source, i.e. achieving pulse compression using fibre gratings rather than the bulk gratings of RefI7]. We have demonstrated the high gain achievable with OP A systems using engineered quasi-phase-matched PPLN. Additionally we show that seeding of a high gain OPA with a low-power, continuous-wave beam (e.g. from a laser diode) provides a convenient means to obtain near transform-limited high power pulses at the seed wavelength, thus greatly enhancing the pulse quality relative to that achievable using a simple OPG. Our approach, assuming a PPLN sample of suitable period and an appropriate temperature allows one to use established fibre laser technology to obtain high-quality, high-power pulsed output at any signal/idler wavelengths for which a seed laser, (e.g. a semiconductor diode laser), is available.

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Identifiers

ORCID for David J. Richardson: orcid.org/0000-0002-7751-1058

ORCID for Peter G.R. Smith: orcid.org/0000-0003-0319-718X

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