  Spectrally intrinsically uncorrelated biphoton states generated from
nonlinear crystals are very important but rare resources for quantum photonics
and quantum information applications. Previously, such biphoton states were
generated from several kinds of crystals, however, their wavelength ranges and
nonlinear efficiencies were still limited for various applications. In order to
explore new crystal for wider wavelength range and higher nonlinear efficiency,
here we theoretically study the generation of spectrally uncorrelated biphoton
states from 14 crystals in the `BBO family', including BBO, CLBO, KABO, KBBF,
RBBF, CBBF, BABF, BiBO, LBO, CBO, LRB4, LCB, YCOB, and GdCOB. They satisfy
three kinds of group-velocity matching condition from near-infrared to telecom
wavelengths. Furthermore, heralded single photons can be generated with a
purity as high as 0.98, which is achieved without any narrow filtering. The
indistinguishability of photons from independent sources is examined by the
Hong-Ou-Mandel interference, which results in a visibility of 98% also without
any further filtering, i.e., photons from different heralded single-photon
sources are highly indistinguishable. Our study may provide single-photon
sources with good performance for quantum information processing at
near-infrared and telecom wavelengths.
