221 K Local Photothermal Heating in a Si Plasmonic Waveguide Loaded with a Co Thin Film

Nana Ota,Tomohiro Miyauchi,Hiromasa Shimizu

doi:10.3390/s21196634

Abstract

Photothermal heaters are important devices for optical switches and memories based on the thermo-optic/magneto-optic effect and phase change materials. We demonstrated photothermal heating in Si plasmonic waveguides loaded with Co thin films by measuring the resistance change upon inputting transverse-magnetic (TM) mode light. Temperature rise is proportional to the light intensity with clear polarization dependence. The photothermal conversion efficiency was estimated at 36 K/mW and maximum temperature rise was estimated at 221 K at steady state upon the inputting 6.3 mW TM mode light for the 400 nm-wide, 8 µm-long and 189 nm-thick Co film deposited on the Si wire waveguide with 129 nm-thick SiO2 buffer layer. The method to increase the efficiency is discussed based on the experimental and simulation results considering the thickness of the SiO2 buffer layer, Co layer and Si core layer, waveguide width, and wavelength. Local photothermal heaters in this study can be applied to a variety of fields including optical switches/memories without electrical control signals in photonic integrated circuits, on-chip optical sensors, and a lab-on-a-chip in biology, chemistry, and medicine.

Highlights

IntroductionPublisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations
We report the fabrication of Si plasmonic waveguides loaded with Co thin films, whose metal resistance changes are measured by a pair of electrode pads
We have reported the design, fabrication, and characterization of Co-loaded Si plasmonic waveguide heaters by measuring the resistance change

Summary

Introduction

Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Recent development of information and communication technology requires larger and larger bandwidth. Optical interconnects based on photonic integrated circuits (PICs) meet this demand and will play important roles in overcoming the limited bandwidth of electrical circuits. There are two problems for a dense integration of optical devices. One problem is the size of optical components. The length of an optical component is limited by the light wavelength, the relatively long length of interaction between light and matter (e.g., the electro-optical (EO), magneto-optical (MO), and thermo-optical (TO)

Methods

Discussion

Conclusion