Optical Power Meter

optical power meter

RA3209A - -70~+3dBm;
RA3209B - -50~+26dBm;

What is Optical Power Meter

Optical power meter used to measure absolute optical power or measure a relative loss of optical power through optical. In optical system, measuring optical power is the most basic thing, is very like the multimeter in electronics. In optical measurements, optical power meter is commonly used in heavy duty work. A optical power meter is able to evaluate the performance of fiber optic transmission equipment by measuring absolute power of optical transmitter unit or optical internet. It is able to measure connection loss, test continuity and help to evaluate transmission quality of fiber link with a power meter and stabilized light source used in combination.

The unit of optical power meter is dbm. In the manual of fiber-optic transceiver or switchboard, has its light-emitting and receiving optical power. Usually, when the emitting is less than 0dbm, the minimum optical power that receiver received is called sensitivity; and the unit of the value that the maximum the receiver received minus the sensitivity is db (dbm-dbm=db), which is known as dynamic range. Emitting power minus received sensitivity is the allowed fiber attenuation values. The value of the optical power that actually emitted minus the actually received is the fiber attenuation (db). The optimum value of optical power that receiver received is “the maximum optical power that could receive – (Dynamic Range /2)”, but generally not so good, because the dynamic range of every optical transceivers and modules is different, so the specific attenuation the fiber allowed depends on how much the actual situation. Generally, it allows 15-30db or so.

Some manuals only have light power and transmission range these two parameters, and sometimes describe to calculate the transmission range through how much fiber attenuation per kilometer, mostly 0.5db/km. with the minimum transmission range divide by 0.5 is the maximum optical power that could receive. If the optical power received is higher than this value, the transceiver might be burned; with the maximum transmission range dived by 0.5 is sensitivity. If the optical power is lower than this value, the link may not work.

There are two ways for fiber connection. One is fixed connection and the other is active connection. Fixed connection is welding, using special equipment to discharge and melt the optical fiber together. The advantage is low attenuation; disadvantage is inflexible and complicated operation. Active connection connect fiber pigtail through connector, usually on ODF. The advantage is simple and flexible operation and disadvantage is high attenuation. Generally speaking, an active connection is equivalent to one kilometer optical fiber attenuation. Fiber attenuation could be evaluated in this way, including fixed and active connection, will attenuate 0.5db optical power per kilometer. If the active connection is very few, the value could be 0.4db. pure fiber doesn’t include active connection, so the value could reduce to 0.3db. the theoretical value of pure fiber is 0.2db/km; for insurance in most case the value is 0.5db.

By Radiasunmeter,Article source:http://www.radiasunmeters.com/ra3209_optical_power_meter.htm