JPH01290327A - Superconducting optical communication equipment - Google Patents

Abstract

PURPOSE:To attain wavelength split multiple communication and to prolong relaying by adding each information bit of a transmission layer for each sequential temperature change while multi-layer structure is adopted for a low temperature tank and using a superconducting element operated at a high speed at each temperature. CONSTITUTION:A low temperature tank 2 is adopted for multi-layer structure as liquid helium liquid hydrogen liquid neon liquid nitrogen, the temperature is changed sequentially, a modulator adding each information bit of the transmission layer required for packet communication for each temperature is constituted by the transmission reception by using processors 6, 7. Photodetectors 8, 10, 13 and light emitting elements 9, 11, 12 made of a superconducting conductor operated at a high speed are used as components at each temperature. Since the depth of modulation is selected sufficiently smaller with respect to the wavelength of the carrier, many information is superimposed on each of carriers varying the frequency by changing the temperature.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a digital communication network, and particularly to a superconducting optical communication device suitable for high-speed communication.

[Conventional technology]

As one method of conventional optical digital communication, a technology called packet communication is used that uses a relay device in the middle to transmit signal information generated by a first processor to a second processor through a communication network.

In this case, it is necessary to divide the information into packets and add pre-control information such as an error correction code and post-temperature control information to the information during relay. Conventional devices have used semiconductors such as Si and GaAs.

[Problem to be solved by the invention]

According to the above-mentioned conventional technology, since a considerable amount of information is added before reception, there is a problem that the speed cannot be increased when a device made of semiconductors is used. Furthermore, in long-distance communications, the number of relay devices increases, reducing the reliability of information transmission.

There is also a system that realizes communication by pulse modulating a coherent optical information signal generated by a semiconductor laser, but since the pulse modulation or pulse receiving means consists of a semiconductor device, there is a limit to the communication speed, and the number of Communication systems that transmit and receive optical signals using optical fibers have not been able to achieve communication at bit rates higher than gigabit per second (Gb/s). It had the characteristic of being able to extend the relay distance compared to . However, even optical fibers have a finite wavelength dispersion characteristic, so they have the drawback of not being able to transmit a high transmission signal on a single wavelength of coherent light.

An object of the present invention is to provide an optical communication device that is highly reliable and capable of high-speed digital communication.

[Means to solve the problem]

The above purpose is a modulation device that uses a cryostat to have a multi-layered structure of liquid helium → liquid hydrogen → liquid neon → liquid nitrogen, changes the temperature in order, and adds each information bit of the transmission layer necessary for packet communication at each temperature. This is achieved by using a photo-detecting element and a light-emitting element made of a superconductor that operate at high speed at various temperatures as elements on the transmitting and receiving sides.

[Effect]

The oscillation frequency of light in superconductors or semiconductors changes depending on temperature. The energy gap Eg, which is the forbidden band of the semiconductor, changes depending on kT. For example, in the case of Si, 4.2 is 1.03eV, and 300 is 1.12eV.
It is.

Therefore, converting this to wavelength i is 4.2, which is 10
33.3 nm, and 1127.2 nm for 300 nm.

G a A s has t'Eg of 1.4 eV at 300, = 880 nm at λ300, and Eg = 1 at 4.2.
．． At 2eV, λ4.2=1030nm. On the other hand, as superconductor light emitting elements, ErBaCuO and NdBaCu
There is an O. It goes without saying that other oxide superconductors can also be used as luminescent elements. In the case of superconductors, the energy gap Eg corresponding to the wavelength λ becomes significantly smaller as the temperature increases and becomes zero at the superconducting transition temperature TO.

Er1. ．． For the composition of 2Ba,...,CuO4, Tc is 9
It becomes 3. Therefore, Eg below about 50 is 0.8 eV
The corresponding λ is a constant value of 1549.9 nm. However, at temperatures higher than that, Eg becomes smaller and λ becomes larger as the temperature rises. For example, at a liquid nitrogen temperature of 77
Since it is 0.6 eV, it is 2200.0 nm. In this way T. Depending on the wavelength λ changes significantly. Tc is E
It is determined by the composition ratio of r and Ba. In other words, it is possible to change the oscillation frequency at a certain temperature by changing the composition ratio of Nd.
The same applies to BaCuO.

E r 1 , 2 B a t3 , B Cu O4
is Tc=82, Eg below 40 is almost constant at 1.2 eV, and λ is 1078.8 nm. At higher temperatures, λ increases significantly as the temperature increases.

Since the modulation depth can be set sufficiently small relative to the wavelength of the carrier wave, a large amount of information can be independently loaded onto each carrier wave whose frequency is changed by changing the temperature.

Therefore, wavelength division multiplexing communication is possible. On the transmitting side, the temperature rises from liquid helium to room temperature as described above, so the frequency of the signal added at each repeater is variable, and heat loss due to temperature gradients can be minimized, reducing energy consumption. It is also a method that gradually ascends with low energy on the low temperature side. Therefore, it is possible to configure a highly reliable communication system with a small number of relay devices. Furthermore, by using a superconductor element that serves as a light emitter and a superconducting photodetector element in the relay device of each layer, a high-speed, low-noise communication device can be obtained.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing the basic configuration of a two-layer optical communication device. By surrounding the low temperature chamber (I) 1 having a temperature of T□ with the low temperature chamber (■) 2 having a temperature of T2 higher than T1, the temperature of T is kept constant.

The left half of FIG. 1 represents the transmitting side, where signals are sent to the signal transmission path 3 through the optical fiber 4. The signal is optical fiber 4
The signal is sent through the signal receiving path 5 to the receiving device shown on the right side of FIG. The processor 6 that generates electrical signal information is composed of a superconducting transistor or a Josephson element, and the superconductor is made of a material whose superconducting transition temperature Tc is higher than T1. This processor 6
It also decodes signals at the same time.

The electrical signal information generated by the processor 6 is converted by the light emitting element 9 into an optical signal having a wavelength λ1.

The light emitting element is made of a superconducting element or a semiconductor element that operates at temperature T1. In the case of a superconducting element, the wavelength λ□ becomes constant at a temperature near TC. Therefore, if T1 is the liquid helium temperature, λ1 is 1549.9 nm when Er1,2Ba, ) and gcu04 are used as the superconducting element. Even when it is composed of other superconductors, or when it is composed of superconductors of the same superconductor material but with different composition ratios, it similarly has its own unique λ1 shown in the above formula, and this value changes with temperature.

Even when a semiconductor is used, the forbidden band width changes depending on the temperature T.

The optical signal with wavelength λ1 is sent to the first repeater, a cryostat (■).
Send to 2. A portion of the signal is converted into an electrical signal by a photodetector element 10 made of a superconductor or a semiconductor, decoded by a second processor 7, and a post-temperature signal containing pre-control information such as an address preamble and a frame check sequence, etc. Control information is added to the light signal, which is converted into an optical signal again by the light emitting element 12, and is transmitted along the signal communication path 3 together with the original information.

The wavelength λ2 at this time is determined by the temperature T2 of the cryostat (■) 2 and has a value different from λ1. For example, when T2 is the temperature of liquid nitrogen, when Er1,2Bao8gcuoa is used in the light emitting element, λ2 is 2200.0 nm.

In this way, the temperature is set to T1. By changing T2, a large amount of information can be independently carried on each carrier wave with a different frequency.

The reception method follows the reverse order of the transmission method, and the information is finally decoded by the processor 6 located in the cryostat (I) 1 at temperature T1.

The optical signal is received from a signal communication path 5 such as an optical fiber to a cryostat (■) 2, which is a first repeater, and a part of the information is converted into an electrical signal by a photodetector element 13, and then sent to a second processor. It is deciphered in 7. Some of the information means pre-control information such as address preamble, post-temperature control information including frame check sequence, etc. processor 7
Necessary information is added thereto, and the light emitting element 11 converts it into an optical signal of wavelength λ2, which is received together with the original information at the cryostat (1) 1. Information consisting of this optical signal is converted into an electrical signal by the photodetector element 8 and decoded by the processor 6.

According to this embodiment, since the modulation depth can be set sufficiently small relative to the wavelength of the carrier wave, a large amount of information can be independently loaded onto each carrier wave whose frequency is changed by changing the temperature. In other words, since modulation can be performed to add each piece of information of the transmission hierarchy necessary for packet communication for each temperature, multiplex communication becomes possible. Therefore, it is possible to increase the interval at which relay devices are installed, and also to perform highly reliable communication.

Furthermore, if the light-emitting element and photo-detecting element are all made of superconducting elements, higher-speed transmission and reception can be achieved.

Noise is also reduced.

FIG. 2 is a configuration diagram showing an example in which the device shown in FIG. 1 is multilayered and the temperature is sequentially changed from liquid helium to room temperature.

Liquid helium temperature is 4.2, liquid hydrogen temperature is 21, liquid neon temperature is 28, and liquid nitrogen temperature is 77K.

It is layered into At each layer, information necessary for packet communication is added using a signal with a wavelength appropriate for that layer.

The light emitting elements and processor photodetecting elements in each layer use a superconductor having a superconducting transition temperature Tc of 4.2 or more in the liquid helium tank 20, 21 or more in the liquid hydrogen tank 30, and 28 or more in the liquid neon tank 40. The liquid nitrogen tank 50 has a base made of a superconductor having a Tc of 77 or more on each level.

With this configuration and the use of superconducting elements, the energy on the transmitting side increases as it approaches room temperature, so it functions effectively as an output buffer, and on the low temperature side, low energy is maintained, minimizing heat loss due to temperature gradients. can be suppressed to

The photodetector element and processor described in the embodiments above.

The light emitting element is preferably composed of a superconducting element such as a superconducting transistor, a superconducting photodetecting element, or a Josephson element, which exhibits high-speed operation and low noise characteristics, but may also be composed of a semiconductor element.

〔Effect of the invention〕

According to the present invention, wavelength division multiplexing communication becomes possible, which increases reliability and lengthens the relay time. The use of high-speed photodetection elements and switching elements improves the transmission speed of information, and the low temperature in the lower layer results in low noise. The hierarchical structure based on temperature has the effect of minimizing heat loss due to temperature gradients.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG. 2 is a block diagram showing the entire structure of FIG. 1...Cryogenic chamber (1), 2...Cryogenic chamber (II), 3.
... Signal transmitting path, 4... Optical fiber, 5... Signal receiving path, 6.7... Processor, 8, 13, 10...
Photodetection element, 9, 12.11... light emitting element.

Claims (1)

[Claims] 1. A first cryostat impregnated with a first information generating means and a first electromagnetic wave pulse generating means generated by a first communication entity, and the first electrode wave pulse generating means. a first receiving device connected to the means by a first electromagnetic waveguide, and causing information generated by the first information generating means based on input information from the first receiving device to reach a target communication entity. a second communication entity that intends to add pre-control information and post-control information necessary for A superconducting optical communication device comprising: a second cryostat for impregnation. 2. The superconducting optical communication device according to claim 1, wherein the temperature of the second cryostat is higher than the temperature of the first cryostat. 3. It is constructed by connecting a plurality of communication bodies in series, each including an information generation means, an electrode wave pulse reception means, and an electromagnetic wave pulse generation means, which are at least partially composed of a superconductor, and the first communication body is with the intention of sending the original information to the communication channel,
The remaining communication entities have the intention of having the information reach the intended communication entity, and the subsequent communication entities connected in series each transmit pre-temperature control information and information to the information signal series generated by the preceding communication entity. Post-temperature control information is added, the first communication entity is impregnated in the first cryostat having the lowest temperature, and the cryostat with a higher temperature provided surrounding the first cryostat is impregnated with a cryostat with a lower temperature. In each of the plurality of cryogenic chambers arranged so as to surround the tank, one communication body in the vertically connected previous stage is impregnated in a cryostat whose temperature is lower than that of the communication body in the latter stage. Features of superconducting optical communication device.