Optical: systems and elements – Optical modulator – Light wave temporal modulation
Reexamination Certificate
2000-01-14
2001-10-02
Epps, Georgia (Department: 2873)
Optical: systems and elements
Optical modulator
Light wave temporal modulation
C359S283000
Reexamination Certificate
active
06297901
ABSTRACT:
CLAIM OF PRIORITY
This application makes reference to, incorporates the same herein, and claims all benefits accruing under 35 U.S.C. §119 from my application OPTICAL ATTENUATING ISOLATOR filed with the Korean Industrial Property Office on Jan. 14 1999 and there duly assigned Ser. No. 846/1999.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an optical component which is used for optical transmission, and more particularly, to an optical component formed by combining an optical attenuator and an isolator, the optical component used as a module.
2. Description of the Related Art
In an optical network, many cases, particularly, a wavelength division multiplexing (WDM) system, use an optical attenuator to equalize optical power. However, when the optical attenuator is used, back reflection may cause a problem. Thus, an isolator is installed to the rear of the attenuator to prevent generation of this problem.
However, the use of an isolator causes several undesirable effects such as additional insertion loss, complexity of the device due to use of additional components, and an increase in the cost due to additional material.
Upon establishment of an optical network, when an optical attenuator and an isolator are connected to each other in series, insertion loss that is the sum of the insertion losses of the two optical devices, is generated. In particular, an optical add drop multiplexer requires as many optical attenuators and isolators as the number of channels, thus increasing the total size of the apparatus.
Also, when an optical attenuator is used without isolators, the back reflection of the optical attenuator is highly likely to cause problems in optical signal transmission.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide an improved optical attenuating isolator.
It is also an object of the invention to provide an optical attenuating isolator which can perform both attenuation and isolation functions.
A further object of the invention is to provide an optical attenuating isolator which does not suffer from back-reflection problems of the attenuator.
A yet further object is to provide an optical attenuating isolator with low insertion loss.
A still further object is to provide an optical attenuating isolator of reduced size.
Another object is to provide an optical attenuating isolator of reduced cost.
To achieve the above objects, an optical attenuating isolator according to an aspect of the present invention is provided, including: a first collimator connected to a first optical transmission medium, the first collimator for collimating light received via the first optical transmission medium; an optical attenuating filter for attenuating the output light of the first collimator; an isolation unit for receiving light attenuated by the optical attenuating filter and passing only polarized light which is polarized in a predetermined specific polarization direction; and a second collimator connected to a second optical transmission medium, the second collimator for collimating polarized light which has passed through the isolation unit, and transmitting the resultant light to the second optical transmission medium.
To achieve the above objects, an optical attenuating isolator according to another aspect of the present invention is provided, including: a first collimator connected to a first optical transmission medium, the first collimator for collimating light received via the first optical transmission medium; an isolation unit for receiving the output light of the first collimator and passing only polarized light which is polarized in a predetermined specific polarization direction; an optical attenuating filter for attenuating polarized light which has passed through the isolation unit; and a second collimator connected to a second optical transmission medium, the second collimator for collimating polarized light which has passed through the optical attenuating filter, and transmitting the resultant light to the second optical transmission medium.
To achieve the above objects, an optical attenuating isolator according to still another aspect of the present invention is provided, including: a polarizer for passing only light which is polarized in a direction that is the same as the direction of polarization of the polarizer, among the received light; an optical attenuating filter for attenuating polarized light which has passed through the polarizer; a Faraday rotator for rotating attenuated light which has passed through the optical attenuating filter by a predetermined number of degrees; and an analyzer for passing only light which is polarized in a direction that is the same as the direction of the analyzer, from among the rotated light.
To achieve the above objects, an optical attenuating isolator according to yet another aspect of the present invention is provided, including: a polarizer for passing only light which is polarized in a direction that is the same as the direction of polarization of the polarizer, among the received light; a Faraday rotator for rotating polarized light which has passed through the polarizer by a predetermined number of degrees; an optical attenuating filter for attenuating light which has passed through the Faraday rotator; and an analyzer for passing only light which is polarized in a direction that is the same as the direction of the analyzer, among the light received from the optical attenuating filter.
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Bushnell , Esq. Robert E.
Epps Georgia
Magee John J.
Samsung Electronics Co,. Ltd.
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