We investigate the influences of structure parameters and interface shapes on the bandwidth of the one-way edge state of lithium niobate valley photonic c

We investigate the influences of structure parameters and interface shapes on the bandwidth of the one-way edge state of lithium niobate valley photonic crystals. By increasing the size difference of two air holes in the same unit cell, we find that the bandwidth of the lossless one-way nontrivial edge state possesses a peak value of 0.0201 (a/λ), which can be used to construct broadband valley photonic crystal waveguide. Mode field distributions verify that the waveguide is robust against sharp bend and exhibits chirality. When the unit cell is arranged in bearded interface with top and bottom components showing negative and positive valley Chern numbers respectively, we find that lithium niobate valley photonic crystal is more likely to exhibit a lossless edge state, which is difficult to be realized in valley waveguides with low refractive index materials. This work can provide a guidance on the design of the high-performance topological waveguide. show less

In this paper, we demonstrate a scheme to tailor both longitudinal and transverse modes inside a laser cavity, and constitute an eye-safe single longitudi

In this paper, we demonstrate a scheme to tailor both longitudinal and transverse modes inside a laser cavity, and constitute an eye-safe single longitudinal mode Er:YAG vector laser. A q-plate is employed as spin-orbital conversion element to modulate transverse mode and obtain cylindrical vector beams. An optical isolator is employed as non-reciprocal element for ring cavity to enforce unidirectional operation and achieve single longitudinal oscillation. The characteristics of power, transverse intensity, polarization spectrum of the output beams are observed. The observed typical single longitudinal mode and highly matched special polarizations prove the successful tailoring of both longitudinal and transverse modes. show less

Lithium niobate (LiNbO3) is a versatile crystalline material for various photonic applications. With the recent advances in lithium-niobate-on-insulator (

Lithium niobate (LiNbO3) is a versatile crystalline material for various photonic applications. With the recent advances in lithium-niobate-on-insulator (LNOI) thin film technology, LiNbO3 has been regarded as one of the most promising platforms for multi-functional integrated photonics. In this work, we present the field enhancement due to collective resonances in arrayed LiNbO3 nanoantennas. These resonances arise from the enhanced radiative coupling of localized Mie resonances in the individual nanoparticles and Rayleigh anomalies due to in-plane diffraction orders of the lattice. We describe the pronounced differences in the field enhancement and field distributions for electric and magnetic dipoles, offering valuable information for the design and optimization of high-quality-factor optical metasurfaces based on LiNbO3.show less

Quantum random access codes (QRACs) are important comunication tasks which are usually implemented in prepare-and-measure scenarios. The receiver tries to

Quantum random access codes (QRACs) are important comunication tasks which are usually implemented in prepare-and-measure scenarios. The receiver tries to retrieve one arbitrarily- chosen bit of the original bit-string from the code qubit sent by the sender. In this paper, we analyse in detail the sequential version of the 3 → 1 QRAC with two receivers. The average successful probability for strategy of unsharp measurement is derived. The prepare-and-measure strategy within projective measurement is also discussed. And it is found that for sequential 3 → 1 QRAC with weak measurement cannot be always superior than the one with projective measurement as the 2 → 1 version be.show less