A roundup of new optical products displayed at Mitsubishi's annual R&D open day in Osaka this week

February 8, 2002

5 Min Read

AMAGASAKI, Japan -- Mitsubishi Electric Corporation has succeeded in developing a long-distance, high-capacity WDM optical transmission system. In tests, the new system transmitted, by means of a single fiber, 65 signals of 20 gigabits/second each, over a distance of 8,400 km. Total transmission speed was 1.3 terabits/second. Development costs relating to next-generation submarine and overland networks can expect to see drastic reductions as a result of this exciting new success. "This is the highest transoceanic class transmission capacity achieved to date," said Takashi Mizuochi, head researcher at Mitsubishi Electric’s Information Technology R&D Center. “The outstanding experimental results obtained were a direct result of the following; a fiber effective area management methodology that ties into greatly improved signal-to-noise ratios; a new symmetrically-collided transmission protocol that suppresses the waveform distortion induced by fiber nonlinear effects; a commercial optical transceiver capable of transmitting 20 gigabits per second and suitable for transoceanic applications; a wide-band, low-noise hybrid optical repeater that features a Raman/EDF (Erbium Doped Fiber) amplifier.”With the transmission speed of each signal rising to 20 gigabits/second, previous data volumes can now be obtained with half the number of waves. Equipment can therefore be more compact, and maintenance and communications costs reduced. Further details of the new technology are due to be announced at the Optical Fiber Communication Conference to be held on March 20, 2002 in Anaheim, California.In a separate release:

AMAGASAKI, Japan -- Mitsubishi Electric Corp. developed an optical cross connect (OXC) prototype which relays data traffic without converting optical signals to electrical signals. This new device looks set to find a wealth of node device applications in metropolitan, core and transoceanic submarine networks, since it enables broadband signals to be transmitted without costly optical-to-electrical conversions.Dynamically supporting optical path establishment, the new prototype also boasts a Generalized Multiprotocol Label Switching-compliant optical path control system. The first of its type to be produced by a Japanese maker, this allows on-demand path setup and teardown, and will also provide access to Virtual Private Networks. In a separate release:

AMAGASAKI, Japan —- Mitsubishi Electric has set a May 2002 product release for three new optical devices geared towards long-distance, high-capacity 40 gigabit / second optical transmission: a tunable dispersion equalizer, an optical modulator and an MEMS optical switch.The tunable dispersion equalizer uses an original grating process to significantly reduce manufacturing errors in grating pitches. Leading the world with regards to group delay time properties, this product boasts a newly developed divided thin film heater that makes possible precision control of grating temperature distribution. As such, the equalizer offers the very highest chromatic dispersion control for 40 gigabit/second optical transmission systems.The optical modulator uses an Fe-doped InP substrate as its base, the excellent insulating properties of which serve to cut parasitic capacitance. Furthermore, flip-chip bonding removes the need for wires connecting individual elements, allowing high-speed operations. For its part, the photodiode uses waveguide elements to bring parasitic capacitance down, and the flip-chip bonding on the preamp poles ties into high speed and high sensitivity.The newly developed MEMS optical switch makes use of the flexibility of polymer waveguides to mechanically switch transmission routes. This innovative concept, based on the suitability of polymer waveguides to mass production, allows switches to offer a loss-less performance not attainable with past technologies. Switching scales up to 32 x 32 can be handled with the new switch.In a separate release:

AMAGASAKI, Japan -- Mitsubishi Electric has introduced a 40 gigabit/second optical modulator and photodiode which uses flip-chip bonding to increase speeds of optical transmission systems. The new technology is ideally suited to 40 gigabit/second transceivers, used in overland optical trunk networks and rapidly expanding metropolitan networks. It is also expected to facilitate cost reductions in next-generation submarine cable networks.“The key components of required optical systems are a modulator to convert electrical signals to optical signals, and a photodiode to reverse the process at the other end. Between them, these components determine the upper speed limit of the system in question,” said Tatsuo Hatsuta, head researcher at Mitsubishi Electric’s Information Technology R&D Center. “Until now, this limit has been low due to the parasitic capacitance of optical semiconductor and electrical IC chips. Inductance between the wires inside the package also placed a low ceiling on performance.” The new product has two characteristics that improve waveform characteristics: a novel optical semiconductor chip structure and superlative flip-chip bonding technology. Cost reductions, difficult to achieve with existing wire bonding techniques, can be realized thanks to homogenous high-frequency characteristics. In a separate release:

AMAGASAKI, Japan -- Mitsubishi Electric has developed a high-speed, low-cost Bascule switch, for use in optical networks and ADSL. The new switch, which drops switching time from 10 milliseconds to .3 milliseconds, is expected to facilitate greater adoption of multi-port, optical cross connect OXC equipment in metropolitan networks. As high-speed, low-cost technologies such as ADSL and optical fiber networks have advanced in Japan, node centers have become clogged and the OXC switching devices responsible for signal routing are now operating at very close to maximum capacity. High-speed transmission relies on optical signals, so all-optical networks require the processing capabilities of OXC devices if they are to improve. The new switch makes use of an innovative Bascule structure, which utilizes the flexibility of polymer waveguides to mechanically switch optical transmission routes. The switch renders lenses and other previously required optical components unnecessary. Mitsubishi Electric Corp. (Tokyo)
Mitsubishi Electric & Electronics USA Inc.

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