**2.2.1 Setup of the system**

The functional block of the present system in a user's home, and categorised into three groups as shown in Fig. 12. The 1st is a continuously power supplied unit, such as a telephone, where a relatively slow transmission speed is allowed (blue block in Fig. 12). The 2nd is medium transmission-speed terminals, indicated as yellow, where both e-mail and network surveying is mainly used. The 3rd is high transmission-speed terminals, indicated as pink, where a dynamic (or moving) image is mainly used. The "Optical LAN System Telephone Office Unit" with a low speed I/F, which is always powered by the least energy takes part in controlling these three units. The other unit of both "Middle Speed I/F" and "High Speed I/F" is always stand-by, and working when communication is needed.

#### **2.2.2 Operation of the present system**

The initial state of the present system is through connection from the "Optical LAN System Telephone Office Unit" (left upper) to the "Optical LAN System Terminal Unit" (low speed I/F : blue block at right lower; continuously power supplied). Without any gating light in a 1x7 optically-gated optical switch, the optical path is automatically selected from an incidence port to a central port of the collecting optical fibre (exit side). The central port of the exit side in a 1x7 optically gated optical switch is connected to an "Optical LAN System Terminal Unit" (blue block at right lower; continuously power supplied). At this time, it is able to occupy a circuit using 980 nm light delivery from an "Optical LAN System Terminal Unit" to the other "Optical LAN System Terminal Unit" via an "Optical LAN System Coupler Unit". By means of these negotiations, an order for occupying the circuit from each "Optical LAN System Terminal Unit" will be arranged by the "Optical LAN System Terminal Unit" (low speed I/F: blue block at right lower; continuously power supplied).

An "Optical LAN System Terminal Unit#1"(right upper one) output gating light from a 980 nm LD in the "Optical LAN System Terminal Unit#1" is used to occupy a circuit for communication. An "Optical LAN System Coupler Unit" delivers gating light of 980 nm from the "Optical LAN System Terminal Unit#1" to both a "1x7 Optical Switch" and an "Optical LAN System Terminal Unit" (low speed unit), which establish communiation of the "Optical LAN System Terminal Unit". After finishing communication (data transfer)

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

The functional block of the present system in a user's home, and categorised into three groups as shown in Fig. 12. The 1st is a continuously power supplied unit, such as a telephone, where a relatively slow transmission speed is allowed (blue block in Fig. 12). The 2nd is medium transmission-speed terminals, indicated as yellow, where both e-mail and network surveying is mainly used. The 3rd is high transmission-speed terminals, indicated as pink, where a dynamic (or moving) image is mainly used. The "Optical LAN System Telephone Office Unit" with a low speed I/F, which is always powered by the least energy takes part in controlling these three units. The other unit of both "Middle Speed I/F" and

"High Speed I/F" is always stand-by, and working when communication is needed.

The initial state of the present system is through connection from the "Optical LAN System Telephone Office Unit" (left upper) to the "Optical LAN System Terminal Unit" (low speed I/F : blue block at right lower; continuously power supplied). Without any gating light in a 1x7 optically-gated optical switch, the optical path is automatically selected from an incidence port to a central port of the collecting optical fibre (exit side). The central port of the exit side in a 1x7 optically gated optical switch is connected to an "Optical LAN System Terminal Unit" (blue block at right lower; continuously power supplied). At this time, it is able to occupy a circuit using 980 nm light delivery from an "Optical LAN System Terminal Unit" to the other "Optical LAN System Terminal Unit" via an "Optical LAN System Coupler Unit". By means of these negotiations, an order for occupying the circuit from each "Optical LAN System Terminal Unit" will be arranged by the "Optical LAN System Terminal Unit" (low speed I/F: blue block at right lower; continuously power supplied).

An "Optical LAN System Terminal Unit#1"(right upper one) output gating light from a 980 nm LD in the "Optical LAN System Terminal Unit#1" is used to occupy a circuit for communication. An "Optical LAN System Coupler Unit" delivers gating light of 980 nm from the "Optical LAN System Terminal Unit#1" to both a "1x7 Optical Switch" and an "Optical LAN System Terminal Unit" (low speed unit), which establish communiation of the "Optical LAN System Terminal Unit". After finishing communication (data transfer)

to shut down, which allows the least stand-by power system.

**2.2.1 Setup of the system** 

**2.2.2 Operation of the present system** 

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

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.

The Least Stand-By Power System Using a 1x7 All-Optical Switch 159

#1 #2 #3 #4 #5 #6 #7

1x7 Optical Switch

WDM LD PD 98LD 98PD

WDM LD PD 98LD 98PD

WDM LD PD 98LD 98PD

WDM LD PD 98LD 98PD

WDM LD PD 98LD 98PD

WDM LD PD 98LD 98PD

WDM LD PD 98LD 98PD

CPL

CPL

CPL

CPL

CPL

Low Speed IF Control

Control

High Speed IF

HPF HPF

Optical LAN System Terminal Unit

HPF HPF

HPF HPF

BPF BPF

BPF BPF Control

High Speed IF

Control

High Speed IF

Control

Middle Speed IF

Control

Middle Speed IF

Control

Middle Speed IF

HUB

#1

#2

#3

#4

#5

#6

#7

HUB

HUB

HUB

HUB

HUB

LPF LPF

BPF BPF

CPL

Fig. 14. Operation of communication between one "Optical LAN System Terminal Unit" and

an "Optical LAN System Telephone Office Unit" using 980 nm light.

CPL

reflector

Optical LAN System Coupler Unit

Reflection-type Star Coupler

Fig. 13. First step of communication among an "Optical LAN System Terminal Unit" using 980 nm light.

Fig. 13. First step of communication among an "Optical LAN System Terminal Unit" using

980 nm light.

Fig. 14. Operation of communication between one "Optical LAN System Terminal Unit" and an "Optical LAN System Telephone Office Unit" using 980 nm light.

The Least Stand-By Power System Using a 1x7 All-Optical Switch 161

Output Power ≧-0.5dBm@Enable≦-45dBm@Disable

LOS Detection ≧-44.0dBm(Detection)≦-26.0dBm(Release)

Electrical Interface ONU Tx+/- 1250Mbps DATA\_IN LVPECL SMA NRZ Burst Enable LVTTL High-Z Active-High

Electrical Interface ONU RX+/- 1250Mbps DATA\_OUT LVPECL SMA NRZ

Controll Item LD ON/OFF LOS Monitor

A versatile optically gated optical switch using an organic dye is suitable for light-path switching in optical communication at various wavelengths of the signal light. The feature of utilizing a thermal-lens effect generated in a thin layer of a dye solution is possible to cover a wide range of wavelengths by varying the types of pigment. An organic dye for absorbing the gating light combined with a high-boiling solvent for forming a thermal lens is properly selected by choosing the wavelengths of both the gating light and the signal light. The formed thermal-lens in a dye solution is very small, which brings about high-

An epoch-making 1x7 optically-gated optical switch has been developed using both a 7 bundled optical fibre with a centre-core distance of 40 μm and a prism of a hexagonal truncated pyramid. Around 0.6 of the coupling efficiency of incidence light to a 7-bundled optical fibre and smaller than 40 dB of crosstalk for both incidence light have been achieved. Using the 1x7 optically-gated optical switch, we have developed a least stand-by power system as well. This system is located in a home, and is composed of the 1x7 optically gated optical switch and a reflection-type optical star coupler, which directly connects between an optical coupler from a telephone office and a PC, TV, IP-phone, etc. Using this system, the

Wavelength 1310-1490 nm

Wavelength 1310-1490 nm Min. Input Power ≦-26.0dBm Max. Input Power ≧-3.0dBm

Extinction Ratio ≧9dB

Display LED Power Supply, LD, LOS Switch SW Power Supply, LD

Controll Interface USB Rev. 2.0 full speed USB-B

Size - W210mm × D350mm × H99mm

Table 3. Specifications of ONU (Optical Network Unit) Optical Interface Unit.

Lock Key LD Source

Power Supply - DC 5V, 0.8 W

Weight - 2.5 kg

least stand-by power in the home will be achieved.

E/O Unit

O/E Unit

Function

Others

**3. Conclusion** 

speed switch of around 1 msec.

Optical Interface

Optical Interface

In Fig. 15, an external view of "The least stand-by power system using a 1x7 optically-gated optical switch" currently being developed is shown. The specifications of both the OLT (Optical Line Terminal) and the ONU (Optical Network Unit) are summarized in Table 2 and Table 3, respectively.

Fig. 15. External view of "The least stand-by power system using a 1x7 all-optical switch".


Table 2. Specifications of OLT (Optical Line Terminal) Optical Interface Unit.


Table 3. Specifications of ONU (Optical Network Unit) Optical Interface Unit.
