| Summary: | 碩士 === 國立臺北科技大學 === 光電工程系 === 106 === In this work, I investigated the soliton dynamics from erbium-doped fiber laser (EDFL) system using graphene oxide (GO) doped polyvinyl alcohol (PVA) polymer (GO/PVA) film as a saturable absorber. The GO/PVA film was prepared using the liquid-phase exfoliation method to produce a nanoscale graphene oxide in aqueous solution and then mixed with PVA sol-gel. The mixed GO/PVA solution was poured into a plastic mold and dehydrated in oven to form a translucent GO/PVA composite film. By means of the transmittance spectrum and Raman spectroscopy, the GO/PVA film shows the transmittance around 56.09 % at 1562 nm and the characteristic peak at D(1345 cm-1) and G(1604 cm-1) band. The modulation depth of GO/PVA film is about 1.39 % at 1566 nm by using the passive mode-locked Erbium-doped fiber laser as a light source. The relatively stable fundamental mode-locked pulses with 9.56 MHz repetition rate and 1.88 ps duration can be achieved with the 92 mW pump power. In addition, a long-term stable mode-locked state over 4 hours was demonstrated by monitoring the RF spectrum and optical spectrum to show the relatively stable central wavelength about 1562 nm and signal to noise ratio (SNR) about 37 dB. As pump power increased, different operation states of EDFL such as multiple pulses from dual pulses to quad pulses can be revealed without rotation of polarization controller. Generally, the number of splitting pulse increased as pump power increased. At high pump powers, two type of soliton rain state (Type I and II) were demonstrate in which the various splitting soliton was generated and moved quickly inside the cavity. The investigation of passive mode-locking in EDFL based on GO/PVA film revealed that the fiber laser can be excellent platform to show the abundant soliton dynamics.
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