Anisotropic model for the fabrication of annealed and reverse proton exchanged waveguides in congruent lithium niobate

Abstract

An anisotropic model for the fabrication of annealed and reverse proton exchange waveguides in lithium niobate is presented. We characterized the anisotropic diffusion properties of proton exchange, annealing and reverse proton exchange in Z-cut and X-cut substrates using planar waveguides. Using this model we fabricated high quality channel waveguides with propagation losses as low as 0.086 dB/cm and a coupling efficiency with optical fiber of 90% at 1550 nm. The splitting ratio of a set of directional couplers is predicted with an accuracy of ± 0.06.

Multiplexed Quantum Random Number Generation

“…The independence of the outcomes of each of the channels was verified from cross-correlation measurements shown in Integrated optics provides a compact and stable way to implement the set of beamsplitters needed to feed many homodyne detectors. We fabricate a 1:32 multiplexer using annealed proton exchanged waveguides in lithium niobate with a device footprint of 60mm x 5mm [34]. The device has insertion losses of ≈7 dB (≈22dB total loss per channel) and we choose balanced outputs to send to the seven homodyne detectors.…”

Research of selective etching in LiNbO3 using proton-exchanged wet etching technique

“…Lithium niobate (LN), known as the optical silicon in the current optoelectronics age, is one of the most widelyused materials for the fabrication of integrated optical devices because of its commercial availability and multifunctional properties [1], such as the excellent transparency from visible to infrared light, high nonlinearity and large electro-optical coefficient [2]. During the past decades, LN material has drawn great attentions in realizing high-density integrated photonic/optical circuits due to its high performance [3], especially with the occurrence of a newly-arisen optical material, namely, lithium niobate-on-insulator (LNOI).…”

Compact all-fiber polarization-independent up-conversion single-photon detector

“…As a low noise and high-efficiency wavelength conversion device, the proton exchanged PPLN waveguide guides only the light wave polarized along the c-axis of the z-cut crystal [18], and all the interacting waves are of the same polarization for type-0 SFG, making use of the highest nonlinear coefficient d33. Up-conversion SPD based on a single waveguide is therefore polarization dependent and extra caution should be taken when up-conversion SPD is used in 3 polarization-independent systems, such as time-bin phase-encoding QKD system which has been proved to be a practical scheme [19][20][21] in complex environmental conditions where the polarization states change randomly during long distance fiber transmission [22][23][24], quantum lidar [25], single photon imaging [26], and biomedical luminescence spectroscopy [27] for which the detected photon polarization is also random.…”