High energy femtosecond fiber chirped pulse amplification system with adaptive phase control

Abstract

We demonstrate increased peak power from an Yb fiber CPA system operating with strong self-phase modulation by shaping the spectral-phase of the input pulses. An adaptive control loop used feedback from the output autocorrelation. We investigated pre-compensation of both SPM phase distortion at high energies, and residual dispersion from mismatched stretcher/compressor technologies at low energies. Phase shaping resulted in improved pulse quality. When using a bulk grating stretcher, shaping increased the autocorrelation peak by a factor of 2.9, and with a fiber stretcher, shaping increased the autocorrelation peak by a factor of 3.4. High-quality 800 fs, 65 microJ recompressed pulses were produced. This technique could benefit a wide variety of fiber amplifier systems and is self-optimising for operation at both low and high pulse energies.

Compensation of optical nonlinearities in a femtosecond laser system in a broad operation regime

“…An optimized laser system performance is achieved in the presence of significant amount of SPM-introduced nonlinear phase evaluated in terms of B-integral up to >4. While similar results have been demonstrated using a free-space pulse shaping [41], [32], [33], the here presented approach shows a clear advantage in terms of its robustness and compactness. The method is applied to a typical ultrafast fiber laser system consisting of few fiber amplifier stages, which can be operated at different repetition rates and with a wide range of pulse energies.…”

“…On the other hand, by intentionally introducing third order dispersion nonlinear phase could be managed to some extent also in CPA fiber systems [29]- [31]. This is even more efficient when applying an almost arbitrary phase pre-compensation using a pulse shaper in a feedback loop with a pulse characterization technique at the laser output [27], [32]- [34]. Although some great results have been reported in the papers mentioned above, non-flexibility of the passive approaches (nonlinear phase is pre-compensated only for a single operation condition) and complexity and inclusion of free-space components (gratings, spatial light modulators, etc.)…”

Adaptive Nonlinear Phase Compensation in a Femtosecond Hybrid Laser with Varying Pulse Repetition Rate

“…There have been many methods already demonstrated that allow for tunable compensation of the nonlinear phase such as the use of different pulse-shaping techniques in a feedback loop with a pulse characterization technique at the laser output [24][25][26][27][28][29]. It was recently shown that a tunable chirped fiber Bragg grating (TCFBG) can efficiently compensate nonlinear phase up to 4π [12].…”

Effects of phase and coupling between the vibrational modes on selective excitation in coherent anti-Stokes Raman scattering microscopy

“…In the past decade, coherent anti-Stokes Raman scattering (CARS) has developed as a promising technique for imaging of various biological species (e.g., living cells and cancerous cells) and also for combustion diagnostics and monitoring of molecules. The recent advances in shaping of ultrafast femtosecond laser pulses [1] along with demonstration of different experimental and theoretical techniques [2][3][4][5][6][7][8][9][10][11][12][13][14] of steering a system to the desired quantum yield has made CARS a major tool of investigation of biological structures. Experimental configurations such as box-CARS [15], frequency modulation CARS (FM-CARS) [16], backward direction (EPI-CARS) [17], heterodyne CARS [18], polarization-CARS [19], Fourier-transform CARS (FT-CARS) [20], and interferometric CARS [21] are among the most promising ones.…”