Temporally shaping biphoton wave packets with periodically modulated driving fields

We describe a method for waveform shaping of narrowband biphotons generated in a double-$\Lambda$ atomic system via four-wave mixing by periodically modulating the input driving lasers. We show that the input field profile(s) can be revealed in the two-photon temporal waveform and its correlation measurement.

Figure 1

(Color online) Schematic of biphoton generation with periodically modulated driving-laser fields. (a) Experimental backward configuration. (b) Multichannel biphoton generation via four-wave mixing in a double-$\Lambda$ atomic system.

Figure 2

(Color online) Conditional two-photon correlation function $R\left(t_s,t_s+\tau \right)$ at $t_s=nT$, where $T=1\mu \text{s}$ is the modulation period and $n$ is an integer. The pump field amplitude is modulated with a sine wave (shown in the inset). The coupling laser operates in the cw mode. The dashed line shows correlation without modulation while the solid line with the modulation.

Figure 3

(Color online) Conditional two-photon correlation function $R\left(t_s,t_s+\tau \right)$ at $t_s=nT$, where $T=1\mu \text{s}$ is the modulation period and $n$ is an integer. The pump field amplitude is modulated with a rectangular wave (shown in the inset). The coupling laser works in the cw mode. The dashed line gives correlation without modulation while the solid line is the correlation with the modulation.

Figure 4

(Color online) Time-averaged two-photon correlation function $R\left(\tau \right)$. Both pump and coupling field amplitudes are modulated with a sine wave. The dashed line shows correlation without modulation and the solid line gives the correlation with modulation.