Skip to main content

Silicon-based Low-cost Passive Optical Components

Objective

This was a technology project in which the main objective was to demonstrate the potential of silica on silicon technology for the fabrication of low-cost single mode passive optical components.
The key feature of using a silicon substrate is that grooves for holding the input and output fibres can be precisely defined as part of the waveguide fabrication process, allowing passive fibre waveguide alignment and making device assembly potentially very low cost. Therefore, a major part of this project was to develop a high-yield, low-cost, integrated process capable of providing high-quality waveguides and precision silicon grooves.
The main objective was to demonstrate the potential of silica on silicon technology for the fabrication of low cost single mode passive optical components. The key feature of using a silicon substrate is that grooves for holding the input and output fibres can be precisely defined as part of the waveguide fabrication process, allowing passive fibre waveguide alignment and making device assembly potentially very low cost. Therefore, a major part of this project was to develop a high yield, low cost, integrated process capable of providing high quality waveguides and precision silicon grooves.
The key achievements of the project overall are summarised as follows: integrated fabrication technology developed, excellent process reproducibility demonstrated, very low loss waveguides achieved (0.1 dB cm{-1} at 1500 nm), passive fibre/waveguides alignment with average losses of less than 0.3 dB per interface achieved, 3 dB directional coupler realised, fully fibre pigtailed in 1 in 16 power splitters and 1 in 4 wavelength mulitplexer/demultiplexer (WMUX/DMUX) devices produced, initial reproducibility and field study on power splitters fibre pigtailed WMUX/DMUX devices completed, feasibility of low loss 1 in 16 WMUX/DMUX demonstrated, low cost potential demonstrated and finally silica on silicon technology shown to be an attractive route to components for the integrated broadband communications network (IBCN).
Technical Approach

The project addressed three main areas:

- the development of fabrication processes to provide high quality waveguides and etched grooves in silicon for fibre alignment on the same wafer.
- the fabrication and evaluation of key prototype passive components for the 1500 nm wavelength region:
- 1:16 optical power splitters
- 4 and 16 channel wavelength mutiplexers/ demultiplexers (WMUX/DMUX)
- 3 dB directional couplers.
- process control, reproducibility and cost.

Key Issues

- Integrated waveguide and etched grooves in silicon process.
- Low-loss passive fibre-waveguide alignment.
- Good process control and reproducibility.
- Low-cost potential of the technology in manufacture.

Achievements

The key achievements of the project overall are summarised as follows:

- integrated fabrication technology developed
- excellent process reproducibility demonstrated
- very low loss waveguides achieved, 0.1 dB/cm at 1500 nm
- passive fibre/waveguides alignment with average losses of < 0.3 dB/interface achieved
- 3 dB directional coupler realised
- fully fibre pigtailed 1:16 power splitters and 1:4 WMUX/DMUX devices produced
- initial reproducibility and field study on power splitters fibre pigtailed WMUX/DMUX devices completed.
- feasibility of low loss 1:16 WMUX/DMUX demonstrated
- low-cost potential demonstrated
- silica on silicon technology shown to be an attractive route to components for the IBCN.

The work on the project has been reported in 15 publications in international journals and a conference.

The current achievements are expected to be exploitable. Discussions have taken place with a SIC production house on the viability of silica on silicon technology for the volume manufacture of passive components. It is concluded that probability of a successful transfer to production are high and that the project has met its main objective of demonstrating the potential of silica on silicon for the fabrication of low cost passive components.

Expected Impact

R1008 will contribute significantly to the overall RACE IBCN objectives in the area of cost reduction of passive optical components. The availability of low-cost components such as WMUX/DMUX devices and power splitters is expected to have a major impact on the economic viability and choice viability and choice of architecture of the IBCN.

This technology has the added potential to produce compact opto-electronic modules of high functionality through the hybridisation of laser, detector and IC chips on the same silicon substrate as the waveguide components and fibre pigtails. No other technology can match all the attractions of silica on silicon, namely, the economic benefits of integration and of totally passive fibre waveguide alignment, the wide range of complex passive components and its overall versatility

Coordinator

BNR Europe Ltd
Address
London Road
CM17 9NA Harlow
United Kingdom

Participants (3)

Alcatel Face SpA
Italy
COMMISSARIAT A L'ENERGIE ATOMIQUE (CEA)
France
Address
31-33 Rue De La Federation
TECHNICAL RESEARCH CENTRE OF FINLAND
Finland