Fiber Optic Wiki

Avago Technologies offers mini-SFP+ optical transceivers

August 12, 2011

Avago Technologies (Nasdaq: AVGO) has unveiled a pair of fiber-optic transceivers designed to increase the port density of Ethernet and storage equipment. The first mini-SFP+ (mSFP), the AFBR-54D7APZ transceiver, targets 8G Fibre Channel for storage applications; the second, the AFBR-703SNZ, is for 10-Gigabit Ethernet.

Optical power meter

August 11, 2011

An optical power meter (OPM) is a device used to measure the power in an optical signal. The term usually refers to a device for testing average power in fiber optic systems. Other general purpose light power measuring devices are usually called radiometers, photometers, laser power meters, light meters or lux meters.

Optical power meter Sensors

August 11, 2011

The major semiconductor sensor types are Silicon (Si), Germanium (Ge) and Indium Gallium Arsenide (InGaAs). Additionally, these may be used with attenuating elements for high optical power testing, or wavelength selective elements so they only respond to particular wavelengths. These all operate in a similar type of circuit, however in addition to their basic wavelength response characteristics, each one has some other particular characteristics.

Optical power meter Power measuring range

August 11, 2011

A typical OPM measures accurately under most conditions from about 0 dBm (1 milli Watt) to about -50 dBm (10 nano Watt), although the display range may be larger. Above 0 dBm is considered "high power", and specially adapted units may measure up to nearly + 30 dBm ( 1 Watt). Below -50 dBm is "low power", and specially adapted units may measure as low as -110 dBm. Irrespective of power meter specifications, testing below about -50 dBm tends to be sensitive to stray ambient light leaking into fibers or connectors.

Optical power meter Calibration and accuracy

August 11, 2011

Optical Power Meter calibration and accuracy is a contentious issue. The accuracy of most primary reference standards (e.g. Weight, Time, Length, Volt etc.) is known to a high accuracy, typically of the order of 1 part in a billion. However the optical power standards maintained by NIST, are only defined to about one part in a thousand. By the time this accuracy has been further degraded through successive links, instrument calibration accuracy is usually only a few %. The most accurate field optical power meters claim 1% calibration accuracy. Comparatively, this is orders of magnitude less accurate than a typical electrical voltmeter.

Optical power meter Extended sensitivity meters

August 11, 2011

A class of laboratory power meters has an extended sensitivity, of the order of -110 dBm. This is achieved by using a very small detector and lens combination, and also a mechanical light chopper at typically 270 Hz, so the meter actually measures AC light. This eliminates unavoidable dc electrical drift effects.

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