Ultrafast serrodyne optical frequency translator

Abstract

The serrodyne principle enables an electromagnetic signal to be frequency shifted by applying a linear phase ramp in the time domain. This phenomenon has been exploited to frequency shift signals in the radiofrequency, microwave and optical regions of the electromagnetic spectrum over ranges of up to a few gigahertz, for example, to analyse the Doppler shift of radiofrequency signals for noise suppression and frequency stabilization. Here we employ this principle to shift the centre frequency of high-power femtosecond laser pulses over a range of several terahertz with the help of a nonlinear multi-pass cell. We demonstrate our method experimentally by shifting the central wavelength of a state-of-the-art 75 W frequency comb laser from 1,030 nm to 1,060 nm and to 1,000 nm. Furthermore, we experimentally show that this wavelength-shifting technique supports coherence characteristics at the few hertz-level while improving the temporal pulse quality. The technique is generally applicable to wide parameter ranges and different laser systems, enabling efficient wavelength conversion of high-power lasers to spectral regions beyond the gain bandwidth of available laser platforms.

Widely Tunable Femtosecond Sources with Continuously Tailorable Bandwidth Enabled by Self‐Phase Modulation

“…Moreover, we have compared the spectral peak detuning and bandwidth of the outmost lobes from the spectral broadening using fused silica plates in MPCs, [52][53][54] and the experimental results also show a good agreement with the prediction from our model. Therefore, our concepts are potentially applicable to different SPM-enabled spectral broadening approaches, such as using bulk materials [73][74][75][76] and gas, [77,78] photonic waveguides, [79,80] hollow-core capillaries, [81] multiplate arrangements, [82] and MPC designs, [37,[52][53][54]83] leading to the control of the spectral peak and bandwidth in different energy levels.…”

“…Tailoring self‐phase modulation by adjusting the initial temporal phase enhances the ability to modify the energy distribution of red‐shifted and blue‐shifted components. [ 37 ] We showed that the asymmetric broadening can also be optimized or precompensated by introducing a proper amount of third‐order dispersion (TOD) to the initial pulse.…”

“…[28] Moreover, with proper spectral filtering of the outmost spectral lobes, SPM-enabled spectral selection (SESS) allows for the demonstration of energy-scalable tunable femtosecond sources. [29][30][31][32][33][34][35][36][37] with temporal contrast enhancement. [36] Furthermore, the nature of automatic phase matching in SPM provides more design freedom to tailor the output pulse and spectrum, and shaping the initial pulses, as well as employing different nonlinear media, leads to the control and optimization of complex nonlinear propagating dynamics.…”

Spatio-temporal pulse cleaning in multi-pass cells

“…In the past few years, multi-pass cells (MPC) have emerged as efficient tools for nonlinear spectral broadening and temporal manipulation of ultrashort laser pulses [1,2], mainly because of their high throughput [3][4][5][6][7], power scalability [8][9][10], high compression factors [6], spatio-spectral beam homogeneity [11], and strong potential for nonlinear spatio-temporal pulse shaping applications [3,12]. The attractiveness of MPCs lies in the fact that extended nonlinear propagation occurs over a relatively small footprint and that large B-integrals can be accumulated in small increments for every pass with minimal spatio-temporal couplings, provided the input beam size is carefully matched to the cell eigenmode and the beam size on the end-mirrors remains fairly constant for every pass [13].…”

Simultaneous nonlinear spectral broadening and temporal contrast enhancement of ultrashort pulses in a multi-pass cell

“…In the past few years, multi-pass cells (MPC) have emerged as efficient tools for nonlinear spectral broadening and temporal manipulation of ultrashort laser pulses [1,2], mainly because of their high throughput [3][4][5][6][7], power scalability [8][9][10], high compression factors [6], spatio-spectral beam homogeneity [11], and strong potential for nonlinear spatio-temporal pulse shaping applications [3,12]. The attractiveness of MPCs lies in the fact that extended nonlinear propagation occurs over a relatively small footprint and that large B-integrals can be accumulated in small increments for every pass with minimal spatio-temporal couplings, provided the input beam size is carefully matched to the cell eigenmode and the beam size on the end-mirrors remains fairly constant for every pass [13].…”