18

Material Science and Technology of Japan, 56（2019）102～108

Jun. 2019

Regular Paper
Refractive Index Control of the Polysilane and Evaluation ofPossibility to Adopt the EO Polymer as Optical Waveguide Material
Kaoru SUGIMOTO1,3,*, Shinya SASAKI2, Tomoyuki AKAHOSHI2,3
and Mitsuhiro WATANABE3
1

Fujitsu Interconnect Technologies Limited, 1-1, Kamikodanaka 4-chome, Nakahara-ku, Kawasaki-shi,Kanagawa 211-8588, Japan

2

Fujitsu Laboratories Limited, 10-1 Morinosato-Wakamiya, Atsugi, Kanagawa, 243-0197, Japan

3

Graduate School of Engineering, Kanto Gakuin University, 1162-2, Ogikubo, Odawara-shi, Kanagawa
250-0042, Japan

Received Sep. 21, 2018; Accepted Dec. 25, 2018
Abstract
A silicone based polymeric material polysilane can be used to form an optical waveguide with the photo-bleaching
method. Combined with a single-mode fiber using a long wavelength band, it is also possible to use it as an opticaldevice. However, it is still quite rare to find an optical device using these kind of polymeric materials as a waveguide.
When making a waveguide for a single-mode type waveguide device, the control of the refractive index difference of
the waveguide material becomes extremely important. To develop the optical device performance, the refractive
index is also required to have a variable function. In this study, we evaluated the bake and exposure process
conditions to control the refractive index of the polysilane and we investigated the possibility to use the EO(Electro-Optical) material as a host polymer.
Keywords: Optical waveguide, Polysilane resin, Single mode, Refractive index, EO Polymer

1.

Introduction

waveguide formation were evaluated and the propagation loss inA silicone based polymeric material polysilane can be

the channel waveguide was observed. Considering that the EO

applied to a 1550 nm long wavelength. It can be applied as anpigments have an optical attenuation function due to theoptical switch as well as an attenuator by combining it with aelectro-optical effect, we evaluated the possibility of using an EO

single mode fiber for long-distance communication to an opticalmaterial made of EO pigments and polysilane. In order to create

device. A lot of studies were conducted on the evaluation of basicthe EO material, we evaluated to viability of the EO material as awaveguide with polysilane, but only few covered the specifichost polymer. The electro-optical effect was measured by the EO

device forming all the core and clad [1-6]. The MZ

coefficient as EO materials contains pigments [11].

(Mach-Zehnder) type modulator is the most widely used devicefor optical switch applications. This switch is made of a material

2.

Experimental method

called LnNbO3. Studies on the EO effects by using a polymeric

2.1

material are also limited [7-10].

2.1.1 Refractive index observation of the slab-waveguide

Waveguide forming

In this study, we develop and evaluate a polysilane resine

In order to form a slab-waveguide, a 4 inch glass wafer

base waveguide for polymer devices covering a long-wavelength(Pyrex glass, thickness: 2 mm) was used as a base waveguideband (1550nm). First, we investigated the refractive index

substrate and the polysilane was spin coated targeting a 10 µm

control to form a single-mode type waveguide. The bake andthickness. Then, the polysilane was cured by the pre-bake andexposure process conditions for an optimal refractive index at thepost-bake processes. Furthermore, the exposure effect was*Corresponding author: sugimoto.kao@jp.fujitsu.com(102)