Loss characterization in rhodamine 6G doped polymer film waveguide by side illumination fluorescence

Colorimetric and absorbance based sensor for sulfide and bicarbonate ions by dye doped polymer composite

We have developed a simple, rapid and cost-effective Dual-channel "colorimetric and absorbance" sensor using polyvinylpyrrolidone (PVP) capped Rhodamine6g (Rh6G) dye composite. Dye-doped polymer composite probe (PVPRH) exhibit intense, narrow absorption properties and long-term stability than the bare Rh6G. The probe's colorimetric relationship with pH was demonstrated by absorption titration. The PVPRH provides a sensitive dual channel method for the determination of sulfide and bicarbonate with colorimetric response and absorption quenching. The synthesized probe, as a two-faced, exhibited remarkable colorimetric responses from orange to pale yellow in the presence of S2- and orange to soft pink in the presence of HCO3- ion, which can be observed by the naked eye also. Under optimal conditions, the relative absorption intensity decreases with increasing ion concentration of sulfide and bicarbonate ions. This trend is observed within the probe solution concentration range of 5 mM to 50 mM. The Dye-doped polymer composite probe is easy, cost effective, rapid, and has real time detection capability for sulfide and bicarbonate ions. The composite probe is stable and optically modified and can be successfully used for detections of S2- and HCO3- ions as strip senor.

Side illumination fluorescence emission characteristics from a dye doped polymer optical fiber under two-photon excitation

Two-photon excited (TPE) side illumination fluorescence studies in a Rh6G-RhB dye mixture doped polymer optical fiber (POF) and the effect of energy transfer on the attenuation coefficient is reported. The dye doped POF is pumped sideways using 800 nm, 70 fs laser pulses from a Ti:sapphire laser, and the TPE fluorescence emission is collected from the end of the fiber for different propagation distances. The fluorescence intensity of RhB doped POF is enhanced in the presence of Rh6G as a result of energy transfer from Rh6G to RhB. Because of the reabsorption and reemission process in dye molecules, an effective energy transfer is observed from the shorter wavelength part of the fluorescence spectrum to the longer wavelength part as the propagation distance is increased in dye doped POF. An energy transfer coefficient is found to be higher at shorter propagation distances compared to longer distances. A TPE fluorescence signal is used to characterize the optical attenuation coefficient in dye doped POF. The attenuation coefficient decreases at longer propagation distances due to the reabsorption and reemission process taking place within the dye doped fiber as the propagation distance is increased.

Fabrication and characterization of dye-doped polymer optical fiber as a light amplifier

The fabrication and characterization of a Rhodamine 6G-doped polymer optical fiber amplifier have been carried out. Two different schemes were employed to characterize the optical fiber: the stripe illumination technique to study the fiber as a gain medium and another technique to study its performance as an amplifier. We observed a spectral narrowing from 42 to 7 nm when the pump energy was increased to 6 mJ in the stripe illumination geometry. A gain of 18 dB was obtained in the amplifier configuration. The effects of pump power and dye concentration on the performance of the fiber as an amplifier were also studied.

Importance of dye host on absorption, propagation losses, and amplified spontaneous emission for dye-doped polymer thin films

The absorption spectra of dye-doped polymer thin films made from a variety of five dyes and six matrices, either organic or organomineral, are analyzed to evaluate the residual absorption in the red wavelength tail and in particular at amplified spontaneous emission (ASE) wavelengths. An absorption cutoff wavelength is defined as the extrapolated wavelength at which the absorption losses are expected to become negligible compared to the structure losses. Such absorption-spectrum-extrapolated wavelengths are compared to the ASE wavelengths and found to correlate for most of the dye-matrix couples. The propagation losses of PM597-doped organic polymers are also measured and accordingly found to increase with the glass transition temperature of the host matrix.

Propagation characteristics and wavelength tuning of amplified spontaneous emission from dye-doped polymer

The propagation characteristics of amplified spontaneous emission (ASE) through a rhodamine 6 G-doped polymethyl methacrylate freestanding film waveguide were studied. This was done by shifting the excitation stripe horizontally along a transversely pumped waveguide. By this method, we could tune the ASE wavelength. The maximum tunability thus obtained was approximately 18 nm with a pump stripe length of 6 mm.