Fabrication and characterization of evanescent wave coupled PbS quantum dots fiber amplifier based on sol-gel method

Abstract

In this paper, size-tunable PbS semiconductor quantum dots were synthesized by sol-gel route and a novel optical fiber amplifier was proposed. Based on fused tapered fiber coupler, the PbS quantum dots film was deposited in the couple region and evanescent wave coupled semiconductor quantum dots fiber amplifier was fabricated. Due to the thinned fiber shape, evanescent wave penetrates into outer surface. When the pumped light are propagated in the evanescent field area, the evanescent wave of pumped light is absorbed by PbS quantum dots, so the PbS quantum dots are excited from ground state to excited state. And when the signal light are propagated in the evanescent field area, the evanescent wave of signal light stimulate PbS quantum dots, the quantum dots return to ground state and release photons which have the same frequency and phase with signal light. With interaction between the evanescent wave power and the coated PbS quantum dots film, the light can be amplified. The optical amplification was obtained at 1310nm wavelength with 980nm wavelength LD as pump.