Lithium niobate on insulator (LNOI) technology is revolutionizing the lithium niobate industry, enabling higher performance, lower cost and entirely new devices and applications. The availability of LNOI wafers has sparked significant interest in the platform for integrated optical applications, as LNOI offers the attractive material properties of lithium niobate, while also offering the stronger optical confinement and a high optical element integration density that has driven the success of more mature silicon and silicon nitride (SiN) photonics platforms. Due to some similarities between LNOI and SiN, established techniques and standards can readily be adapted to the LNOI platform including a significant array of interface approaches, device designs and also heterogeneous integration techniques for laser sources and photodetectors. In this contribution, we review the latest developments in this platform, examine where further development is necessary to achieve more functionalities in LNOI integrated optical circuits and make a few suggestions of interesting applications that could be realized in this platform. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Status and Potential of Lithium Niobate on Insulator (LNOI) for Photonic Integrated Circuits

New optical waveguide technology for integrated optics, based on propagation of long-range surface plasmon polaritons (LR-SPPs) along metal stripes embedded in dielectric, is presented. Guiding and routing of electromagnetic radiation along nanometer-thin and micrometer-wide gold stripes embedded in polymer via excitation of LR-SPPs is investigated in the wavelength range of 1250-1650 nm. LR-SPP guiding properties, such as the propagation loss and mode-field diameter, are investigated for different stripe widths and thicknesses. A propagation loss of /spl sim/6 dB/cm, a coupling loss of /spl sim/0.5 dB (per facet), and a bend loss of /spl sim/5 dB for a bend radius of 15 mm are evaluated for 15-nm-thick and 8-/spl mu/m-wide stripes at the wavelength of 1550 nm. LR-SPP-based 3-dB power Y-splitters, multimode interference waveguides, and directional couplers are demonstrated and investigated. At 1570 nm, coupling lengths of 1.9 and 0.8 mm are found for directional couplers with, respectively, 4- and 0-/spl mu/m-separated waveguides formed by 15-nm-thick and 8-/spl mu/m-wide gold stripes. LR-SPP-based waveguides and waveguide components are modeled using the effective-refractive-index method, and good agreement with experimental results is obtained.

/pdf/integrated-optical-components-utilizing-long-range-surface-ej45tsgl8i.pdf

Integrated optical components utilizing long-range surface plasmon polaritons

Piezoresponse force microscopy (PFM) detects the local piezoelectric deformation of a sample caused by an applied electric field from the tip of a scanning force microscope. PFM is able to measure deformations in the sub-picometre regime and can map ferroelectric domain patterns with a lateral resolution of a few nanometres. These two properties have made PFM the preferred technique for recording and investigating ferroelectric domain patterns. In this review we shall describe the technical aspects of PFM for domain imaging. Particular attention will be paid to the quantitative analysis of PFM images.

https://iopscience.iop.org/article/10.1088/0022-3727/44/46/464003/pdf

Piezoresponse force microscopy (PFM)

Biomedical microfluidic devices by using low-cost fabrication techniques: A review.

The notorious implication of integrated optics in the nowadays communication systems makes more interesting the development of optical integrated devices and circuits. The evolution of the communication systems was sustained by the integrated optics and it is obvious that the actual interests in the optical communications are also transferred and adapted to integrated optics. The presentation of actual state-of-the-art in this field is a good opportunity both for an evaluation on the above mentioned evolution and for discerning the actual trends and their perspectives. These trends, guided by applicative goals, have to be discussed not only from the theoretical point of view but also from a practical one.

Optical integrated circuits

We propose a rapid prototyping method for the fabrication of optical waveguides based on the direct laser-printing method of ultrafast Laser-Induced Forward Transfer (LIFT) followed by further processing. The method was implemented for the fabrication of titanium in-diffused lithium niobate channel waveguides and X-couplers by LIFT-depositing titanium metal followed by diffusion. Propagation loss as low as 0.8 dB/cm was measured in preliminary experiments.

/pdf/laser-induced-forward-transfer-a-rapid-prototyping-tool-for-5fjg8717oc.pdf

Laser-induced-forward-transfer: a rapid prototyping tool for fabrication of photonic devices

Modelling of titanium indiffused lithium niobate channel waveguide bends: a matrix approach

A generally applicable method to simulate the two-dimensional profiles of Ti-concentration and refractive index of Ti:LiNbO3, waveguides is presented. The influence of the fabricational parameters on the refractive index profiles has been studied in detail. The model parameters are extracted from the available experimental data. The computed values of surface refractive index change agree closely with the experimental results. The model is also extended for coupled waveguides.

Pranabendu Ganguly

Papers

Laser-induced-forward-transfer: a rapid prototyping tool for fabrication of photonic devices

Modelling of titanium indiffused lithium niobate channel waveguide bends: a matrix approach

Simulation of refractive index profiles for titanium indiffused lithium niobate channel waveguides

Modal profiles in Ti:LiNbO3 two-waveguide and three-waveguide couplers by effective-index-based matrix method

Semi-analytical analysis of lithium niobate photonic wires