Mitsubishi develops fast 16-way optical switch

Engineers at Mitsubishi Electric have developed a 16-way optical cross-connect switch for use in metropolitan area fibre networks...

Engineers at Mitsubishi Electric have developed a 16-way optical cross-connect switch for use in metropolitan area fibre networks which, they claim, is faster than similar products from other companies.

Tatsuo Hatta, a manager of the company's opto-electronics team at Mitsubishi's Information R&D centre, said the switch can connect and disconnect fibre paths in less than one millisecond or around one-tenth the time of components already in use.

At the heart of the device is a component called a Bascule optical switch. This consists of a small square polymer sheet into which a 16-by-16 waveguide grid has been scored. Directly below each point where the waveguides cross is a 0.3mm-diameter ball - the same type as that used in a ballpoint pen - and beneath that is a piezo-actuator.

When the actuator is switched off the ball is at rest and light passes directly through the junction, but when energised the actuator pushes the ball up so it impacts the polymer. This creates a break in the waveguide and light then takes a 90-degree turn. In this way light from any of 16 input fibres can be switched to another one.

The Bascule switch has several advantages over competing technologies being pushed for use in such optical cross-connect systems, said Hatta. Compared with micro-electrical-mechanical systems-type switches, which bounce light off small mirrors, the new component is about 10 times faster and has reduced signal loss. Against thermo-optical effect switches the speed is also faster and the power consumption is much less, he claimed.

Mitsubishi's first product samples based on the 16-way switch and a previously developed eight-way switch should be available by September. Mass production is planned within the next 12 months.

The company will first target the metropolitan area optical network market, which is expected to expand as broadband communication systems become more pervasive.

At the end of 2003 there were just under 900,000 subscribers to fibre-to-the-home Internet service in Japan against 10.2 million DSL and 2.5 million cable internet subscribers.

Mitsubishi Electric has 14 domestic and seven overseas patents pending on the technology.

Martyn Williams writes for IDG News Service

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