Temperature Dependence of Ion-Exchanged Waveguides on Glass: From Fabrication to Environmental Impact

M2 Internship Proposal
Temperature Dependence of Ion-Exchanged Waveguides on Glass:
From Fabrication to Environmental Impact

Location: CROMA Lab (UMR 5130), Grenoble, France
Supervisors: Lionel BASTARD and Davide BUCCI
Period and length: Spring 2026, 6 months.

Why this project?
Waveguides are at the heart of many optical technologies — from telecommunications to lab-on-chip sensors. Among the different platforms used to build these devices, glass stands out as a low-cost, robust, and optically transparent material [1][2]. It’s also compatible with microfluidics, making it ideal for next-gen bio-sensors.

At CROMA, we’ve been developing integrated optics on glass for nearly 40 years using a technique called ion exchange. This process changes the glass’ refractive index by replacing sodium ions (Na⁺) with other ions like potassium (K⁺) or silver (Ag⁺), allowing us to “write” waveguides into the material.

But there’s a challenge: temperature. Ion exchange relies on heat to diffuse ions into the glass (typically above 300°C), and later steps like wafer bonding[3] (100–150°C) could potentially affect the waveguides’ quality. So how stable are these waveguides across different temperatures? And at the same time, can we make this process more eco-friendly?

Internship Objectives
During this internship, you’ll help answer that question by working at the intersection of materials science, integrated optics, and sustainability.

________________________________________________________________________________
# integrated photonics
# glass technology
# life-cycle analysis

Desired profile & skills
2nd year Research Master or
3rd year Eng. School
– Microtechnology & fabrication
– Photonics
– Affinity & curiosity for experi-mental and numerical work

Send application to:
Lionel BASTARD
Davide BUCCI

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