Mode-locked biphoton generation by concurrent quasi-phase-matching

Abstract

We report a scheme for mode-locked biphoton generation by engineering quasi-phase-matching materials. An aperiodically poled lithium tantalate is designed to supply multiple reciprocal vectors for two-photon frequency comb generation. Temporally, such two-photon state exhibits mode-locked pulse train. The two-photon pulse duration reaches 4.2 fs when the frequency comb is centered at 800 nm and covers 442 nm. The HOM interference of the mode-locked biphoton approaches a 1.26-$\ensuremath{\mu}$m dip and exhibits a reappearance of dip and peak, which can be taken as a new scheme for engineering quantum light source. Furthermore, we also design another aperiodically poled crystal to generate two sets of frequency combs. The HOM interference will appear as a revival of spatial beatings. The mode-locked biphotons suggest applications in precise time synchronization, quantum metrology, quantum optical coherence tomography, and quantum computing.