Near-field observations of light confinement in a two dimensional lithium niobate photonic crystal cavity

Jean Dahdah,Fadi Baida,Nadège Courjal,Maria Pilar-Bernal,Gwenn Ulliac

doi:10.1063/1.3647770

Abstract

We report the characterization of a lithium niobate photonic crystal cavity using near field scanning optical microscopy (NSOM) operating in collection scanning mode. The cavity is implemented on an annealed proton exchange waveguide by focused ion beam milling. We observe a confinement of the optical field at the center of the cavity by analyzing the collected light with a probe positioned above the photonic structure. The experimental NSOM results obtained are compared to numerical results obtained by finite difference time domain method. A good agreement is obtained between theoretical and experimental results where a cavity mode appears around λ = 1540 nm.

Highlights

During the past twenty years, photonic crystals (PhCs) have been attracting much attention, due to their periodic structures that can prevent the propagation of light at certain frequencies
We present a photonic crystal H1 cavity integrated on a lithium niobate substrate
In this letter, we reported near field scanning optical microscopy (NSOM) measurements of optical fields confined to a subwavelength twodimensional PC-H1 microcavity based on lithium niobate

Summary

INTRODUCTION

During the past twenty years, photonic crystals (PhCs) have been attracting much attention, due to their periodic structures that can prevent the propagation of light at certain frequencies Implementing such photonic crystal structures on a material like lithium niobate (LiNbO3), which is strongly sensitive to external phenomena, offers great possibilities of developing ultra-compact active integrated optical components. Electro-optical, acousto-optical or nonlinear LiNbO3 PhCs have been demonstrated recently with low driving power and with an active length as small as a few tens of microns.1–4 These developments were performed by writing a perfectly periodic structure on a bulk LiNbO3 substrate. Using a NSOM in collection mode, the electromagnetic field is confined within the cavity at the resonance wavelength

WAVEGUIDES AND PHOTONIC CRYSTAL FABRICATION TECHNIQUES

FAR FIELD

NEAR FIELD

Findings

CONCLUSIONS