Wavelength division multiplexing device

Details Wavelength division multiplexing device Wavelength division multiplexing device

1999-10-06

2001-09-25

Pascal, Leslie (Department: 2633)

Optical: systems and elements

Deflection using a moving element

Using a periodically moving element

C359S199200, C359S199200, C359S199200, C359S199200, C359S199200, C359S855000, C359S590000, C359S589000, C359S583000, C359S634000

Reexamination Certificate

active

06295150

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to a wavelength division multiplexing device which is useful as means for remarkably increasing transmission information when used for transmitting light signals in optical communication, optical LAN and optical measurement control.
PRIOR ART OF THE INVENTION
In recent years, with remarkable improvements in performances of personal computers and rapidly increasing diffusion of internet, information handled in information networks such as optical communication and optical LAN is markedly increasing in amount. For increasing the transmission capacity of lines for the above increased information, there is one method in which more optical fibers are laid. However, the above method is not expedient since it requires a large amount of a cost. Recently, there is therefore rapidly developing a wavelength division multiplexing method in which existing optical fibers are used and lights having different wavelengths are multiplexed and transmitted to increase the capacity. The above method is epochal as a low-cost method, since the transmission capacity per wavelength is the same as in a conventional method so that the transmission capacity can be remarkably increased with an increase in the number of wavelengths to be multiplexed.
In a wavelength division multiplexing method generally employed by communication service carriers, however, the increased number of wavelengths is gained by using wavelengths having intervals of the order of approximately 1 nm in order to increase the transmission capacity to a great extent, so that a wavelength division multiplexer and parts constituting it have required very high-degree control.
For example, a laser diode (LD) causes a shift in light wavelength depending upon temperatures, and it is therefore required to maintain the temperature of the device at a constant temperature. Further, when an optical filter is used, it also requires very strict control. Due to these, the wavelength division multiplexer is inevitably expensive.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a wavelength division multiplexing device which can easily utilize existing optical fibers and increases the transmission capacity to make it approximately several times mainly in a short-range information communication network.
According to the present invention, there is provided a wavelength division multiplexing device comprising, as essential elements, a pair of 1×N optical couplers (2≦N≦16), N light emission devices in which one of peak wavelengths thereof differs from every other one by at least 30 nm and N light receivers having optical filters having light-transmission wavelength bands adjusted to correspond to said peak wavelengths,
wherein the light emission devices and the light receivers having optical filters corresponding to peak wavelengths of the light emission devices form pairs, said light emission devices or said light receivers are optically connected to N-port-side ports of one of the 1×N optical couplers, and each optical filter is defined by the following expression (1),
|&lgr;−&lgr;
h
|≧0.01&lgr;+2(nm)  (1)
wherein &lgr; (nm) is a light wavelength of a light emission device, which is to form a pair with an optical filter, at a room temperature, and &lgr;
h
(nm) is a wavelength corresponding to 50% of transmittance of the optical filter in an optical absorption curve near &lgr;.


REFERENCES:
patent: 3722977 (1973-03-01), Sloane
patent: 3722978 (1973-03-01), Sloane et al.
patent: 4636078 (1987-01-01), Podvin
patent: 5870513 (1999-02-01), Williams
patent: 5933553 (1999-08-01), Ziemann

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