YTTERBIUM-ERBIUM CO-DOPED FIBER. The ytterbium level creates a very broad and intense pump-band-enabling the use of a wide range of high power pump sources. See manufacture test data at the pdf link below. It was customized product by INO http://www.ino.ca/en-ca/Achievements/Description/project-p/specialty-optical-fiber-products.html Since we failed to measure the fiber length by OTDR for this very special fiber, we have to use traditional method to estimate the fiber length. The fiber roll height is about 75mm (net), the fiber roll diameter is about 0.162-meter. The fiber coating is 0.25mm, so the fiber length is approximately 0.162*75/0.25*3.1416=152 meter. So this fiber spool is in full or almost full original length of 145-meter. Following general knowledge is from another maker Fibercore: Erbium-Ytterbium Co-doped Fiber for High Power CATV and FTTx / PON Amplifiers Why Erbium and Ytterbium? Erbium doped fibers have been used in fiber amplifiers ‘EDFAs’ for about 20 years and now provide excellent service in a wide variety of high performance amplifiers, manufactured in OEM volumes, throughout the World – so why complicate matters by co-doping with ytterbium? The trouble with erbium, is that it is not particularly soluble in the primarily silica core-matrix of an optical fiber. Solubility is improved significantly by modifying this matrix through the addition of alumina but, use too much and the core begins to take-on opaque, crystalline characteristics. The result is that an erbium doped fiber will simply cease to generate any useful level of gain at pump absorptions of only several tens of dB/m. Whilst these relatively low dopant concentrations are fine for low-power EDFAs, directly core-pumped using 980 nm, singlemode diode lasers, much higher levels of absorption are needed to take advantage of cladding-pumping using high power, low-cost multimode pump diodes. High Power and Low Cost Per Milliwatt Unlike erbium, ytterbium is highly soluble in typical optical fiber core matrices with the result that singlemode absorption figures as high as a thousand dBs per metre or greater may be achieved without adversely affecting efficiency. In a cladding pump fiber, where the effective pump absorption is reduced to a small fraction of the singlemode figure, this dramatic increase in pump absorption enables typical amplifier gain lengths of 10 metres or shorter to be realised – simplifying packaging and reducing cost when compared with equivalent erbium-only cladding-pump fibers. The unique shape of the ytterbium absorption spectrum also offers significant advantages over erbium. Erbium typically needs wavelength-stabilized, TE-cooled pump diodes, to lock the pump diode onto one or other of its narrow absorption peaks, whereas ytterbium provides a much flatter, ‘Absorption Plateau’, particularly at practical, multimode pump wavelengths around 940 nm. This ‘Plateau’ can enable the use of un-cooled pump lasers – reducing costs and power consumption and enhancing overall system reliability. Unique Shape of the Er:Yb Spectrum Enables Use of Un-Cooled 940 nm Pumps Ytterbium on its own generates gain close to 1100 nm and must be co-doped with erbium in order to shift this gain into the Third Telecoms Window around 1550 nm. In order to effect efficient energy transfer from ytterbium to erbium, phosphorus must be introduced into the core matrix. This phosphosilicate core is amongst the most difficult optical fiber core matrices to fabricate – demanding exceptional levels of process control to guarantee consistency, reproducibility and avoid phase-separation. Note: 10-meter fiber was just removed from this spool. So there is near 135 meter left.