Saturable and two-photon absorption in zinc nanoparticles photodeposited onto the core of an optical fiber

Abstract

In this work, the simultaneous presence of saturable (SA) and two-photon absorption (TPA) in zinc nanoparticles (ZnNPs) photodeposited onto the core of an optical fiber was studied in the nanosecond regime with the P-scan method using a high gain pulsed erbium-doped fiber amplifier. An analysis based on Mie theory was carried out to demonstrate the influence of the absorption coefficient with the particles sizes in the proximity of surface plasmon resonance (SPR). The shift from TPA to SA has been observed as the irradiance is increased. It was found that for irradiances lower than 5 MW/cm², TPA is dominant, whereas for irradiances higher than 5 MW/cm², the SA becomes dominant. Furthermore, the values of the nonlinear absorption coefficient and the imaginary part of third-order nonlinear optical susceptibility were calculated numerically from the transmittance measured. Such TPA makes ZnNPs a candidate for optical limiting applications, and SA makes them a candidate for applications in pulsed fiber laser systems.

Measurement of two-photon absorption by gold nanoparticles of different sizes photodeposited onto the core of an optical fibre

“…This absorption peak also shows a shift towards the UV region for smaller nanoparticles. This behaviour is a well-known phenomenon that is attributed to the absorption by AuNPs, extinction coefficient and consequently to the effect of surface resonance plasmon (SPR) [21]. Studies have shown that the changes in the value of the SPR peak are due to the morphology, geometric dimensions and dielectric constants of a material [15,24].…”

“…Gold nanospheres were photodeposited onto the core of an optical fibre using the technique previously reported by a continuous wave laser source at 1550 nm and 50 mW as is shown in Fig. 1(a) [21,22]. AuNPs with diameters of 10, 20, 50 and 100 nm were acquired from Sigma-Aldrich company (741957, 741965, 742007 and 742031) and stabilized in a citrate buffer.…”

“…The theoretical study was carried out using the Beer-Lambert law [21,22], that relates the attenuation of the intensity of radiation with the properties of the material by means of the transmission. In this work, the relationship between transmittance and absorbance is approximated by the expression where L is the thickness of the sample, I is the intensity, α 0 and β are the linear and nonlinear absorption coefficients, respectively.…”

“…where λ is the wavelength, ε 0 is the permittivity in free space, c is the speed of light in vacuum, and n 0 is the refractive index of AuNPs [21]. We can convert the units of Im(χ (3) ) in (esu) using the conversion formula 1 (esu) = 1.398 × 10 -8 m 2 /V 2 .…”

Steady-State 3D Trapping and Manipulation of Microbubbles Using Thermocapillary

“…Explorer 532-200-E) is coupled into a multimode optical fiber (OF G , 50/125 µm), using an aspherical lens with a focal distance of 4.5 mm as shown in Figure 1. Previously, AgNPs were immobilized using the photodeposition technique at the distal end of the fiber OF G [21][22][23]. The optical power loss caused by AgNPs absorption was approximately 2 dB.…”