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… Show more
“…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.…”
The capability of locally engineering the nonlinear optical properties of media is crucial in nonlinear optics. Although poling is the most widely employed technique for achieving locally controlled nonlinearity, it leads only to a binary nonlinear state, which is equivalent to a discrete phase change of π in the nonlinear polarizability. Here, inspired by the concept of spin-rotation coupling, we experimentally demonstrate nonlinear metasurfaces with homogeneous linear optical properties but spatially varying effective nonlinear polarizability with continuously controllable phase. The continuous phase control over the local nonlinearity is demonstrated for second and third harmonic generation by using nonlinear metasurfaces consisting of nanoantennas of C3 and C4 rotational symmetries, respectively. The continuous phase engineering of the effective nonlinear polarizability enables complete control over the propagation of harmonic generation signals. Therefore, this method seamlessly combines the generation and manipulation of harmonic waves, paving the way for highly compact nonlinear nanophotonic devices.
“…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.…”
The capability of locally engineering the nonlinear optical properties of media is crucial in nonlinear optics. Although poling is the most widely employed technique for achieving locally controlled nonlinearity, it leads only to a binary nonlinear state, which is equivalent to a discrete phase change of π in the nonlinear polarizability. Here, inspired by the concept of spin-rotation coupling, we experimentally demonstrate nonlinear metasurfaces with homogeneous linear optical properties but spatially varying effective nonlinear polarizability with continuously controllable phase. The continuous phase control over the local nonlinearity is demonstrated for second and third harmonic generation by using nonlinear metasurfaces consisting of nanoantennas of C3 and C4 rotational symmetries, respectively. The continuous phase engineering of the effective nonlinear polarizability enables complete control over the propagation of harmonic generation signals. Therefore, this method seamlessly combines the generation and manipulation of harmonic waves, paving the way for highly compact nonlinear nanophotonic devices.
“…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].…”
Section: Introductionmentioning
confidence: 98%
“…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].…”
Section: Introductionmentioning
confidence: 99%
“…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.…”
We investigate wavefront engineering of photon pairs generated through spontaneous parametric down conversion in lithium niobate-based nonlinear photonic crystals (NPCs). Due to the complexity of domain structures, it is more convenient to describe photon interaction based on the nonlinear Huygens-Fresnel principle than conventional quasiphase matching regime. Analytical expressions are obtained to describe the transverse properties of down-converted photon states. The convenience of domain engineering in LiNbO 3 crystals provides a potential platform for flexible wavefront manipulation of multiphoton states. The generation of N00N state with orbital angular momentum in a twisted NPC is studied utilizing this method. The obtained state is of great value in quantum cryptography, metrology, and lithography applications.Index Terms-N00N state, wavefront engineering, nonlinear photonic crystal, spontaneous parametric down-conversion.
“…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.]…”
Since cavity-phase matching has been experimentally realized, the efficiency is limited to 20%. In this Letter, we successfully achieved a conversion efficiency as high as 41% with a slope efficiency of 48.5% using cavity-phase matching, by reflecting the pump beam at the end surface of the KTiOPO(4) crystal. The high performance of the device makes it a promising candidate to substitute for quasi-phase-matching material.
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