Optimizing the phase-matching parameters of a BIBO crystal for ultrafast spontaneous parametric down conversion

We analyze and optimize the parameters of the Type I spontaneous parametric down-conversion (SPDC) process in BiB3O6 (BIBO) crystal directly from calculations. This can be used to construct a system to generate ultrafast entangled photon pairs, which play an important role in quantum communication, quantum positioning, and quantum clock synchronization. Our work on the problem makes it clear that the optimal phase matching orientation in the process of SPDC is a key mechanism in the BIBO crystal in a way that appears not to have been appreciated before. In the case of ω = 0.405 μm , the numerical results of the optimization parameters at room temperature ( 295 K ) are:θ = 152.00°,φ = 90°, and deff = 3.48 pm/V. Finally, we use a pair of 0.6 mm thick biaxial BIBO crystals to construct an ultrafast entangled photon source, where the crystals are stacked together perpendicularly and pumped by a 405 nm pulsed laser doubling from a Tsunami mode-locked Ti:sapphire laser