Evanescent-field optical amplifiers and lasers

An optical amplifier based on fiber side-polishing technology with the merits of high pumping efficiency, low noise figure and small footprint has been new designed in this creation. The following three statements show the major breakthrough of this new structure. (1) The fabrication of side-polished fiber devices with very long effective interaction length (~20 mm) and in conjunction with highly doped Erbium glass attached to its surface has made the evanescent-pumped optical amplifiers being practical. (2) An addition of a slanted fiber grating inscribed in the core at fiber polished region can spatially separate the signal and pump power to improve the pumping efficiency and optimize the leaky depth of signal evanescent field, simultaneously. This can significantly alleviate the output power jitters due to gain-medium's index drift from heat absorption. (3) An ""active-cladding and passive-core"" structure can efficiently keep the spontaneous emission from being amplified and therefore high quality amplified signals can be produced. The motivation of this creation is to design an optical amplifier with good optical qualities, small footprint and low cost with moderate gain, which are advantageous to be employed in fiber metropolitan and access networks.