At this time we have been successful in developing two new optical communications related products:'the 10Gbit/s fiber optic transceiver '& 'the PLC (Planar Light wave Circuit) type VOA (Variable Optical Attenuator) for DWDM (Dense Wavelength Division Multiplexing)'.

Responding to the proliferation of the Internet & the widening of multimedia services; high speed, large capacity optical transmission networks have started being built worldwide & the development of optical devices to answer these market needs is becoming strong. We are of course, also concerned about responding to these needs & so have been trying to develop a number of new products & results from the two aforementioned ones have proven to be one of our successes.

Under we would like to give an outline of these two successfully developed products:

1. 10Gbit/s fiber optic transceiver

An optical transceiver is an optical device which converts electrical signals & optical signals by being incorporated into the information transmission & processing devices of products such as general-purpose computers & routers. Amongst those starting to embrace the real multimedia information society, from the major companies & ISPs (Internet Service Providers) we are seeing the demand for larger capacity information communication devices increasing & because of this increased demand, it is also becoming essential for them to use higher speed optic transceivers.

Up to now we have developed & mass-produced optic transceivers with transmission speed ranges from 100Mbit/s to 2.5Gbit/s. However, with the tendency towards higher speed transmissions the development of a transceiver that could cope with a 10Gbit/s transmission speed - a speed four times higher than all existing products - was becoming a matter of urgency. Along with customer friendly marketing that allowed us to quickly develop products based on their needs & other information - we overcame many technological problems, in a short time to make a smaller, lower power-consumption product. This success in realizing this miniature 10Gbit/s optical transceiver for data transmission systems is a world first.

Regarding product specifications, we expect that the series will include a range from 2km for short distance use, up to a maximum of 80km for long distance use. In order to increase the efficiency of usage of the communication line, a Time Division Multiplexing transmission (*1) is used, where the circuit is usually a separate device from the optic transceiver. But with the Time Divided Multiplexing function being installed inside our new 10Gbit/s transceiver, the design load on the router maker customer side can be greatly alleviated.

In the future we want to lead the way in the global market with the development of highly competitive products like these & by investing in markets we hope to reinforce our position as the leading supplier of high end optical transceivers for data transmission systems & be able to respond to the vigorous demand that is forecast in this area.

2. PLC type VOA for DWDM.

Regarding major communication companies, centered mainly in America - because information transmission capacities are set to increase, they are introducing the DWDM System (Dense Wavelength Division Multiplexing) (*2). However, in an environment where information transmission capacities are going to increase more & more -the further 'multi channeling 'of DWDM Systems is going to be promoted. In order to transmit over long distances, when the optical signal becomes attenuated mid way through transmission, an optical fiber amplifier for amplification is essential. However, because the amplification rate differs depending on the wavelength there is the problem that on the receiving signal side, fluctuations of the signal strength occurs over every channel. Therefore, in order to promote 'multi channeling' for long distance transmissions, it is becoming indispensable to control the fluctuation of signal strength over every channel.

The device that can control these fluctuations is a VOA. The VOA is placed on the transmitting signal side & by adjusting optical input power according to the special characteristics of the optical paths (such as: the differences of amplification rate in each channel & mid way scattering loss in long distance transmissions) - the optical output power at the receiving signal end can be regulated.

The existing VOA (mechanical type), adjusted the optical output inside the optical fiber by using a douser, but depending on usage conditions it was easy for moveable parts to go wrong, thus reliability was a problem. Because of interleavers etc., PLC (Planar Light wave Circuit) (*3) has high technical ability & performance & this PLC technology is used by the waveguide type VOA that we have now developed. This new product works on the thermo-optic effect (*4), where the refractive index of the PLC is changed by heating it with a heater & the value of optical attenuation is controlled. As the new waveguide type VOA has no moveable parts, compared to the existing mechanical type VOA it has been able to make significant progress regarding reliability & because of this it has become possible to use it with peace of mind even in trunk lines, where a cut off mid transmission is impermissible.

In the future we intend to get a timely grip on the markets & technology trends relating to optical devices for PLC technology applied WDM & by doing this develop further new products & plan positive business development.

*1	Time Division Multiplexing Transmission. It functions by allocating a single high-speed cable to multi low speed signal cables - it is technology which is shared. With our newly developed 10Gbit/s optic transceiver, the 16 electrical signals - with a transmission speed of 622Mbps & the single optical signal - with a transmission speed of 10Gbit/s have a mutual exchange function.
*2	Dense Wavelength Division Multiplexing One of the communication technologies that uses optical fibers. Multiple optical signals, that have different wavelengths, are injected & then transmitted into a single optical fiber at the same time, meaning that it is a technique which allows a greatly increased volume of information transmission through a single optical fiber core & this is known as WDM (Wavelength Division Multiplexing). To respond to an increase in the numbers of wavelengths because of heightened demand for information amounts, data transmission amounts can be greatly increased at low cost compared to the option of increasing the number of new transmission routes themselves. At a higher density than WDM is DWDM (Dense Wavelength Division Multiplexing).
*3	PLC: (Planar Light wave Circuit) PLC is the optical circuit formed on surface of a silica substrate etc. that utilizes the same technology as the semiconductor processing technology of photolithography & dry etching that is used to form the minute structure of IC & LSI. It can give a variety of special characteristics, depending on its pattern.
*4	Thermo-optic Effect Phenomena: changes of optical characteristics, such as the refractive index etc, according to temperature. Because of this, it is usually necessary to fix the temperature of the optical parts that are used in wave-guide technology, but conversely the current products use these special characteristics. With the changing of the temperature of the wave-guide, the refractive index of the silica glass (whose temperature changing characteristics as a raw material are used in a positive way) is altered & by controlling the optical path, optical output power is adjusted.