Fig. 1. (a) Schematic of a χ⁽²⁾-based optical modulator that provides a reciprocal-type transfer function. It consists of an OPA that is pumped by a quasi-continuous-wave laser and seeded by an amplitude-modulated (AM) laser. The output signal waveforms A_out(t) calculated for (b) a square-modulated seed signal A_in(t) and for (c) a sinusoidal AM seed signal A_in(t). Here, A_p and A_v denote the modulation peak and valley of a sinusoidal AM seed signal.

Fig. 2. (a) Amplitude evolution of the incident modulation peak (solid line) and valley (dotted line) versus the crystal length. (b) Amplitude evolution of the first five orders of sidebands A_(n), where n refers to the order for each sideband.

Fig. 3. (a) The amplitude (vertical lines) and phase (red circles) of each sideband for the pump, idler and signal calculated at various crystal lengths of (a) L = 0, (b) L = L_p = 12.8 mm, (c) L = 14.5 mm and (d) L = 21.5 mm. The right-hand column presents the corresponding waveforms of the signal (blue solid line), pump (black solid line) and idler (green dashed line).

Fig. 4. (a) The output signal amplitude A_out versus incident signal amplitude A_in (blue), which agrees well with a reciprocal-type transfer function (red). The inset plots the incident (black) and output signal waveform calculated by numerical simulation (blue) and Equation (5) (red). (b) The spectrum of the output signal (blue) and the fitting based on Equation (10). (c) The number of sidebands (with the relative amplitude ≥0.1) and the temporal duration of the output signal against the change of ER. (d) Stability of the output pulse duration and temporal contrast against the change of crystal length.

Fig. 5. (a) Temporal waveform and (b) power spectral density of the output pulse train calculated in the presence of PSF without (blue) and with bandpass filtering (red), respectively. Temporal waveform of the output pulse train calculated for (c) GVM_si = 0 (black), 90 fs/mm (blue), 500 fs/mm (red) and (d) GVM_sp = 0 (black), 800 fs/mm (blue), 1200 fs/mm (red). Other simulation parameters are set the same as in Figures 3(d) and 4(a).