**2.1.2 A dye-cell as one of the most important parts**

The most important residual component for degradation of the dye solution in a quartz cell is both oxygen and water. Therefore, a dye-cell made of a quartz capillary is prepared in a vacuum glove box. First, a solvent "S" is dried using a molecular sieve for several hours. Second, a freeze-pump-thaw treatment of a dye-dissolved solution is employed several tens of times in a vacuum glove box. Next, a quartz capillary of outer diameter of 1 mm, inner diameter of 0.5 mm and 25 mm length is sealed at one end after being dried in a vacuum groove box. A dye of YKR3080 dissolved in a solvent "S" with a high concentration near saturation is charged into the capillary by a micro-syringe. Another end of the capillary is sealed temporally by glue in the vacuum glove box. At the outside of the glove box, another end of the capillary is sealed by melting quartz using a micro burner (Fig. 8).

Fig. 8. Micro cell made of a quartz capillary: outer diameter of 1 mm, inner diameter of 0.5 mm and 25 mm length. Both the purification and sealing processes are performed in an ultra-pure vacuum glove box.

### **2.1.3 A 7-bundled optical fiber**

Two types of a 7-bundled optical fibre are developed: one is for incidence and the other is for collecting. The incidence optical fibre is composed of a centre fibre for the signal light and 6-outer fibres for the irradiating gating-light to a dye cell. The diameter of the clad of a single mode optical fibre for optical communication is reduced from 125 μm to 40 μm, so as to reduce the centre-to-centre distance of the core to 40 μm in a 7-bundled optical fibre as

The Least Stand-By Power System Using a 1x7 All-Optical Switch 155

The optical-fibre line from a telephone office is directly connected to a 1x7 optically gated optical switch (Fig. 1). A terminal unit (optical interface; Opt-I/F) of the present system is connected directly between a 1x7 optically-gated optical switch and a PC, TV, IP-phone and so on. It serves as a controller of the 1x7 optically gated optical switch for light-path switching of the PC and so on. This unit sends a command to another terminal unit for negotiation among the terminal units using a line having a wavelength of 980 nm. All terminal units connected to a 1x7 optically gated optical switch via a reflection-type optical star coupler in the 980 nm line can establish completely independent collision-free

Several functions of optical LAN of the present system connected to a telephone office are as follows (Fig. 11). The Ethernet of the electrical and optical performance is Tx of 1550 nm and Rx of 1310 nm, Filtering of data communication involves 1000 base-T, 100 base-T and serial communication, Communication of the control system for data communication, and The

Several functions of optical LAN of the present system connected to a PC, TV, IP-phone and so on are as follows. The Ethernet of the electrical and optical performance is Tx of 1310 nm and Rx of 1550 nm, Filtering of data communication involves 1000 base-T, 100 base-T and serial communication, Communication of the control system for data communication, The Measurement of energy consumption for each port, and Gating-light of 980 nm for controlling a 1x7 all-optical switch. Function of a reflection-type optical star coupler in 980

nm line is delivery of gating-light to each 1x7 optically-gated optical switches.

Fig. 11. Overview of the present system for demonstration. Left upper is a unit for establishing an IP Network、a TV network, and so on in a home network. Top middle is "Reflection-type Star Coupler" with the 1x7 optically-gated optical switch. Right blocks are

7 downstream units from the 1x7 optical switch located in a user's home.

**2.2 The least stand-by power system** 

communication among these terminal units.

Measurement of energy consumption for each port.

shown in Fig. 9(a); 7 optical fibres are assembled as the closest packing configuration in a sleeve of inner diameter 120 μm.

Fig. 9. Incidence (a) and collecting (b) 7-bundled optical fibre composed of a single-mode optical fibre (core diameter of about 10μm). Centre fibre of (b) is lightened.

The collecting optical fibre is composed of 7 optical fibres for the collecting signal light, where the centre-to-centre distance of the core is 250 μm; 7 optical fibres with a clad diameter of 125 μm are independently set up in a ferrule with 7 holes, as shown in Fig. 9(b).

#### **2.1.4 A prism of hexagonal truncated pyramid for improving the throughput to the receiving optical fiber**

A 3 mm diametre prism of the hexagonal truncated pyramid set up between the focusing lenses is employed for enhancing the coupling efficiency to a collecting 7-bundled optical fibre (Fig. 10). This prism brings rectangular incidence of refracted light from a dye-cell to a collecting optical fibre. The non-refracted signal light, i.e., in the case without the gating light, passes through a flat area of the centre top in the prism. The refracted signal light, in the case with gating light, passes through the side slope in the prism (one of the 6-polished surfaces).

Fig. 10. Prism of a hexagonal truncated pyramid made by a glass-mould pressing method.

## **2.2 The least stand-by power system**

154 Optical Communications Systems

shown in Fig. 9(a); 7 optical fibres are assembled as the closest packing configuration in a

Fig. 9. Incidence (a) and collecting (b) 7-bundled optical fibre composed of a single-mode

**2.1.4 A prism of hexagonal truncated pyramid for improving the throughput to the** 

A 3 mm diametre prism of the hexagonal truncated pyramid set up between the focusing lenses is employed for enhancing the coupling efficiency to a collecting 7-bundled optical fibre (Fig. 10). This prism brings rectangular incidence of refracted light from a dye-cell to a collecting optical fibre. The non-refracted signal light, i.e., in the case without the gating light, passes through a flat area of the centre top in the prism. The refracted signal light, in the case with gating light, passes through the side slope in the prism (one of the 6-polished surfaces).

Fig. 10. Prism of a hexagonal truncated pyramid made by a glass-mould pressing method.

The collecting optical fibre is composed of 7 optical fibres for the collecting signal light, where the centre-to-centre distance of the core is 250 μm; 7 optical fibres with a clad diameter of 125 μm are independently set up in a ferrule with 7 holes, as shown in Fig. 9(b).

optical fibre (core diameter of about 10μm). Centre fibre of (b) is lightened.

sleeve of inner diameter 120 μm.

**receiving optical fiber** 

The optical-fibre line from a telephone office is directly connected to a 1x7 optically gated optical switch (Fig. 1). A terminal unit (optical interface; Opt-I/F) of the present system is connected directly between a 1x7 optically-gated optical switch and a PC, TV, IP-phone and so on. It serves as a controller of the 1x7 optically gated optical switch for light-path switching of the PC and so on. This unit sends a command to another terminal unit for negotiation among the terminal units using a line having a wavelength of 980 nm. All terminal units connected to a 1x7 optically gated optical switch via a reflection-type optical star coupler in the 980 nm line can establish completely independent collision-free communication among these terminal units.

Several functions of optical LAN of the present system connected to a telephone office are as follows (Fig. 11). The Ethernet of the electrical and optical performance is Tx of 1550 nm and Rx of 1310 nm, Filtering of data communication involves 1000 base-T, 100 base-T and serial communication, Communication of the control system for data communication, and The Measurement of energy consumption for each port.

Several functions of optical LAN of the present system connected to a PC, TV, IP-phone and so on are as follows. The Ethernet of the electrical and optical performance is Tx of 1310 nm and Rx of 1550 nm, Filtering of data communication involves 1000 base-T, 100 base-T and serial communication, Communication of the control system for data communication, The Measurement of energy consumption for each port, and Gating-light of 980 nm for controlling a 1x7 all-optical switch. Function of a reflection-type optical star coupler in 980 nm line is delivery of gating-light to each 1x7 optically-gated optical switches.

Fig. 11. Overview of the present system for demonstration. Left upper is a unit for establishing an IP Network、a TV network, and so on in a home network. Top middle is "Reflection-type Star Coupler" with the 1x7 optically-gated optical switch. Right blocks are 7 downstream units from the 1x7 optical switch located in a user's home.

The Least Stand-By Power System Using a 1x7 All-Optical Switch 157

against for "Optical LAN System Telephone Office Unit", the "Optical LAN System Terminal Unit#1" broadcast to the "Optical LAN System Terminal Unit" end of communication using 980 nm light, releases the occupied circuit. By these procedures, the connection of the circuit becomes the initial state shown in Fig. 12. By the alternative action described above, each "Optical LAN System Terminal Unit"(#1~#6) can communicate

Fig. 12. Full system of the innovative least stand-by power equipment. The blue block at the right lower indicates a unit continuously supplied with power (low speed I/F). Three pink blocks at the right upper (high-speed I/F) and three yellow blocks at the right middle (middle-speed I/F) indicate users. The white block at the centre indicates a reflection-type star-coupler. The white block at the upper centre indicates an optically-gated optical switch.

The pink block at the left upper indicates a unit in a telephone office.

alternatively to the "Optical LAN System Telephone Office Unit".

An "Optical LAN System as a Telephone Office Unit" and a "Telephone Office PC" (left upper in Fig. 11) are a virtual unit for establishing an IP Network、TV network, and so on in the home network; 7 downstream units from a 1x7 optical switch are settled in a user's home. An "Optical LAN System Coupler Unit" (top middle in Fig. 11) consists of a "Reflection-type Star Coupler", which carries both communication among each "Terminal PC" and control of the 1x7 optical switch distributing gating light of 980 nm in a user's home. Each "Terminal PC" communicates with each other using gating light of 980 nm via the "Optical LAN System Terminal Unit". When one "Terminal PC" is ready to communicate using the circuit (a connected circuit is free from exclusiveness), an order is sent to select the 1x7 optically-gated optical switch using 980 nm light. Then, the circuit between the "Optical LAN System as a Telephone Office Unit" and the "Terminal PC" are occupied and begin to communicate. Using the present system, the idling "Terminal PC" is to shut down, which allows the least stand-by power system.
