Abstract
Quasi-phase-matching (QPM) has enriched the capacity of parametric down-conversion (PDC) in generating biphotons for many fundamental tests and advanced applications. However, it is not clear how the non-idealities and randomness in the QPM grating of a parametric down-converter may affect the quantum properties of the biphotons. This thesis intends to provide insights into the interplay between PDC and non-ideal or random QPM structures. Using a periodically poled nonlinear crystal with short periodicity, we conduct experimental and theoretical studies of PDC subject to non-ideal duty cycle and random errors in domain lengths. The work described in this thesis has been published in Scientific Reports 6, 26079 (2016)