Review Article: Quasi-phase-matching engineering of entangled photons

Abstract

Quasi-phase-matching (QPM) technique has been successfully applied in nonlinear optics, such as optical frequency conversion. Recently, remarkable advances have been made in the QPM generation and manipulation of photon entanglement. In this paper, we review the current progresses in the QPM engineering of entangled photons, which are finished mainly by our group. By the design of concurrent QPM processes insides a single nonlinear optical crystal, the spectrum of entangled photons can be extended or shaped on demand, also the spatial entanglement can be transformed by transverse inhomogeneity of domain modulation, resulting in new applications in path-entanglement, quantum Talbot effects, quantum imaging etc. Combined with waveguide structures and the electro-optic effect, the entangled photons can be generated, then guided and phase-controlled within a single QPM crystal chip. QPM devices can act as a key ingredient in integrated quantum information processing

Continuous control of the nonlinearity phase for harmonic generations

“…So far there has been no demonstration of a material that allows continuous and arbitrary phase control for the local nonlinear polarizability. Such a nonlinear material would enable exact phase matching conditions for nonlinear optical processes, in contrast to the widely used quasi-phase matching scheme, in which only the sign of the nonlinear polarizability can be manipulated [1][2][3][4][5][6] . It may remove further undesired nonlinear processes which are introduced by the higher Fourier components of the nonlinear susceptibility in a periodically poled system.…”

Generation of N00N State With Orbital Angular Momentum in a Twisted Nonlinear Photonic Crystal

“…Among such crystals, the domain-engineered lithium niobate crystal is a valuable candidate [13], [15], [16]. Owing to the mature processing technologies [17]- [19], suitable domain structure could be flexibly introduced into the LiNbO 3 crystals for SPDC engineering [15], [16], [20]. Moreover, the multifunctional feature of LiNbO 3 crystal also brings opportunities for function-integrated quantum circuits [11], [15], [21].…”

“…One of the most popular kind of NPC is the domain-inverted ferroelectric crystals which are selectively poled to drive the sign of χ (2) changing between positive and negative with certain patterns [13], [14]. Among such crystals, the domain-engineered lithium niobate crystal is a valuable candidate [13], [15], [16]. Owing to the mature processing technologies [17]- [19], suitable domain structure could be flexibly introduced into the LiNbO 3 crystals for SPDC engineering [15], [16], [20].…”

“…Tailoring the wavefront of entangled photons has been demonstrated to play an important role in spatial entanglement [20], [22] and orbital angular momentum entanglement of photons [23], which are valuable resources for quantum communication [24], [25], metrology [26], [27] and imaging [16], [28], [29]. In these works, the parametric processes for tailoring wavefront are usually described in conventional phase matching regime.…”

High-performance cavity-phase matching by pump reflection

“…Quasi-phase matching (QPM) in an optical superlattice (OSL) [1,2] is a widely used technique to make efficient frequency conversion possible, in applications such as beam and pulse shaping, multiharmonic generation, all-optical processing [3], and the generation of entangled photons [4]. However, limited by the fabrication technique, most QPM materials are ferroelectric crystals [such as LiNbO 3 (LN), KTiOPO 4 (KTP), etc.]…”