Chirped-pulse-amplification system using a polarization-maintaining fiber stretcher matched to a Volume Bragg Grating

Summary form only given. Chirped Pulse Amplification (CPA) systems using Ytterbium-doped fibers for amplification, Chirped Fiber Bragg Gratings (CFBG) for stretching, and diffraction gratings for compression are a reliable source of high-energy ultrashort pulses at wavelengths around 1μm [1]. Much more compact systems can be realized by replacing the grating compressor unit with Volume Bragg Gratings (VBG) and stretching in either VBGs [2] or CFBGs [3]. A disadvantage of these systems is the lack of dispersion variation and the difficulty of sufficiently exact dispersion matching in the production process of the VBG and the CFBG and the phase and amplitude ripples in these elements.Here we present a compact fiber CPA system similar to [4], consisting of a composite PM fiber stretcher and VBG compressor with dispersion matching up to the third order. Pulses with 10 nm bandwidth at 1030 nm central wavelength were generated. The VBG exhibits 13 nm spectral bandwidth and a stretching factor of 27 ps/nm, thus the pulses are stretched to 270 ps duration. Adjusting the length of positive and negative TOD PM fiber to 550 m and 20 m, respectively, we could achieve a compressed pulse duration of 270 fs FWHM (retrieved from the measured autocorrelation FWHM of 360 fs, see Fig. 1b). This value is close to the transform limit of 237 fs for the measured spectrum (Fig. 1b, inset). The achieved pulse peak power compared to the transform-limited case (temporal Strehl ratio) is calculated to 85%.