There is a clear need for low cost, high performance and large-scale production of photonic chips. Network development requires more interconnecting components. A flexible and low-cost process using good quality material is necessary.
The sol-gel process is a chemical method to fabricate glasses at ambient pressure and moderate temperature. The resulting material properties can be tuned depending on the precursors used. Hybrid materials, mixing organic and inorganic parts, offer the advantages of polymer-like materials and glasses.
We have developed sol-gel-processed integrated optical circuits using hybrid materials. We report on the development of active devices based on the thermo-optic effect. Thermo-optic coefficients as high as -2.10-4/°K have been measured in our materials. This enables the design of compact devices with low power consumption. Our goal is to utilise the thermo-optic effect in the development of integrated optical switches. The kHz response time of such switches makes them unsuitable for modulation applications, but they can be used for network protection, reconfiguration purposes in routing and multiplexing applications such as Code Division Multiplexing. New designs, based on multimode interference couplers (MMIC), have also been created.
In this work we first describe the synthesis of the hybrid materials as well as the fabrication processes. Using the measured properties of the materials developed, we can simulate the optical and thermal properties of the target devices. The simulation results have been exploited to model and optimise a range of switch designs, including MMI-based 1xN switches. Finally, we report on the full characterisation of the different structures and devices created in terms of fabrication quality and optical and thermal response.
Planar lightwave circuits (PLCs) made from photo-patternable sol-gel materials are attracting considerable R&D interest. This is due to the advantages they offer for applications in optical telecommunications and their compatibility with existing silicon technology process equipment. In particular, the ability to produce devices compatible with silica optical fibres using a straightforward, environmentally friendly, photolithographic process is very attractive. The approach is now well-established in the literature and typically involves the incorporation of an acrylate moiety in the sol-gel precursor mixture, thereby providing a photo-polymerisability function. In this work, we report on the fabrication of passive optical components and devices designed for datacomms applications using visible diode lasers or the 1st telecom window. Silica-based sol-gel waveguides have been integrated in an opto-electronic multichip module (OE-MCM) demonstrator for optical interconnect applications. We have fabricated an 8-channel transmitter module for parallel optical interconnects (POI) based on 2 sub-modules: (a) an optical interface sub-assembly based on photo-patterned sol-gel optical waveguides, and (b) an optoelectronic component sub-module comprising an array of VCSELs. We describe here the fabrication, characterization and performance of the optical components and a POI Transmitter chip.