If there is a 3db loss that means 50 percent of the light were lost.

Optical circulator is a multi-port optical device with nonreciprocal property. It is based on the nonreciprocal polarization of an optical signal by Faraday effect. When an optical signal is input from any port, it can be output from the next port sequentially with very low loss, and the loss from this port to all other ports is very large, so these ports are not communicating with each other.

That means that optical circulator is a three- or four-port optical device designed such that light entering any port exits from the next. If light enters port 1 it is emitted from port 2, but if some of the emitted light is reflected back to the circulator, it does not come out of port 1 but instead exits from port 3. This is analogous to the operation of an electronic circulator.

Fiber-optic circulators are used to separate optical signals that travel in opposite directions in an optical fiber, for example to achieve bi-directional transmission over a single fiber. Because of their high isolation of the input and reflected optical powers and their low insertion loss, optical circulators are widely used in advanced communication systems and fiber-optic sensor applications.

Optical circulators are non-reciprocal optics, which means that changes in the properties of light passing through the device are not reversed when the light passes through in the opposite direction. This can only happen when the symmetry of the system is broken, for example by an external magnetic field. A Faraday rotator is another example of a non-reciprocal optical device, and indeed it is possible to construct an optical circulator based on a Faraday rotator.

Structure Principle

It consists of a Faraday rotator and two polarizing prisms on both sides. When polarized light passes through a Faraday rotator, its polarization plane can rotate 45°under the action of an external magnetic field. As long as the optical axes of the two polarizing prisms are set at an appropriate angle to each other, the insertion loss of the inter-connected optical paths can be very low and the isolation of the disconnected optical path is very large.

The optical circulator can also be formed by utilizing the characteristics of the single-mode fiber will produce the Faraday rotation effect under the action of an external magnetic field. The insertion loss and isolation of the polarization-independent optical circulator are independent of the polarization state of the incident light.

Technical Parameters

The technical parameters of optical circulator include insertion loss, isolation, crosstalk, polarization dependent loss(PDL), polarization mode dispersion(PDM) and return loss, etc. The definitions of insertion loss, isolation, polarization dependent loss and polarization mode dispersion of optical circulators are basically the same as those of optical isolators, except that for an optical circulator, it refers to a specific index between two adjacent ports.

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if one buys a pair of glasses and i break them with in 1 year, does sams store/optical replace the pair of glasses.

GLSUN optical cable monitoring system, combined with OTDR, optical switch, and upper-level network management software, form a systematic and intelligent system integrating functions of testing, analysis, alarm, positioning, information management, and worksheet. It features high integration density, strong commonality, abundant product form, and flexible upgrading and expansion.

Fiber In-Service Monitoring

Light sources of different wavelengths will not interfere with each other in the transmission process in optical fiber. Based on this principle, we combine the service light [wavelength 1550] and test light [wavelength 1650] for transmission, so that the quality of optical fiber can be monitored without interruption of service.

Spare Fiber Monitoring

Spare fiber monitoring is to inject the monitoring signal into the spare fiber and indirectly observe the loss of other fiber in the cable by monitoring the loss of the spare fiber. Since the monitoring signal goes through the spare optical fiber, passive device such as filter is not required, which can effectively reduce the installation process and cost of the system.

Fiber Out-of-Service Monitoring

Optical fiber out-of-service monitoring refers to monitoring the original communication optical fiber in the condition that communication equipment is interrupted. Therefore, passive devices such as filter are not required, which can effectively reduce the installation process and system cost of the system. The disadvantage is that communication equipment needs to be interrupted.

Application: Optical switch + OTDR Monitoring Scheme

Optical power monitoring scheme can monitor the total loss of optical fiber, but it can not reflect the loss performance of optical fiber, nor can it find the fault of optical fiber. While OTDR can monitor the loss performance of the fiber. It can find the failure type and accurately by analyzing the OTDR curve.

Since OTDR costs are relatively high, optical switch is needed to switch to different optical fibers, so as to reduce the cost of the whole system. By controlling the 1xN optical switch, the control unit starts the OTDR to test the optical fiber loss performance in turn. By analyzing the test curve of OTDR, the purpose of optical fiber monitoring is achieved.

Application: Optical Power Detector + Optical Switch + OTDR Monitoring Scheme

This scheme can effectively solve the problem of poor timeliness for fault report of optical switch + OTDR scheme. The optical power detector monitors the total loss of the optical fiber in real-time. If any abnormality is found, the control unit is informed to start and switch to the abnormal optical fiber and conduct OTDR fiber performance test. The alarm type and will be identified by analyzing OTDR curve. The control unit can also control the OTDR and optical switch for periodic tests and roll call tests. However, this scheme still has the problem of poor timeliness caused by OTDR polling in case of abnormality of multiple monitored fibers.

Application: PON + Optical Switch + OTDR Monitoring Scheme

With the development of FTTX, PON network monitoring and maintenance has been mentioned on the agenda by telecom operators or special network users. Glsun developed high sampling accurate OTDR module for PON monitoring.

Reference from www dot glsunmall dot com