E. F. Chillcce

Comparison of Plasmonic Arrays of Holes Recorded by Interference Lithography and Focused Ion Beam

In this paper, we compare the geometric characteristics and the optical properties of plasmonic hole arrays recorded in gold (Au) films using two different techniques, namely, focused ion beam (FIB) and interference lithography (IL). The morphology of the samples was analyzed using a scanning electron microscope (SEM), and the plasmonic peaks were measured from the transmission spectrum of the samples. The diameters of the holes recorded by IL present approximately the same statistical deviation as those fabricated by FIB but in a much larger area. Although the transmittance measurements of both types of samples exhibit the characteristic plasmonic peaks, the intrinsic fabrication errors of each technique affect differently the optical spectra.

Tellurite Glasses for Optical Amplifiers

Tellurite glasses present interesting physical and optical properties, such as high rates of linear and nonlinear refraction, low melting points, low and medium frequencies of phonons, and especially high solubility for rare-earth ions. Tellurite glasses became potentially important for the manufacture of optical amplifiers with high bandwidth for optical communications in the region of infrared spectrum. The high solubility property for rare-earth ions, especially the erbium ions, allows the manufacture of optical fiber amplifiers as small as possible. A large number of studies have been published with virtually all rare-earth ions, such as tellurite glass doped with erbium, ytterbium, praseodymium, thulium, holmium ions, and others, and were manufactured and put in optical amplifier trade with high bandwidth of 1550 nm involving tellurite glass ions co-doped with erbium and thulium ions. Of great importance was the manufacturing method, mainly rod in tube method of fiber with a double shell. Lately, micro-structured optical fiber amplifiers doped with erbium ions have been developed.

Tellurite microstructured optical fibers doped with rare-earths for optical amplification

We present experimental results of optical amplification by using Er3+-doped tellurite MOFs. Also, a study of broadband near infrared emission in Pr3+ single-doped and Pr3+/Yb3+ codoped tellurite-tungstate glasses to perform new MOFs is presented.

Sm3+ effects in the Tm3+ doped tellurite glass for S-band amplification

Thulium doped Samarium codoped tellurite-tungstate glasses were produced. Luminescence properties in the infrared region were investigated looking to observe improved properties for S-band amplification in the co doped samples. Thulium is well-known by the 3H4-3F4 radiative transition emitting around ~1.47μm, which is a self-terminating transition in tellurite hosts due the longer lifetime of the lower level in relation to the upper level of this transition. Analysis of absorption and emission spectra showed that we could quench the 3F4 level significantly, what improved the intensity of the emission at 1.49μm. However, the state 3H4 were also quenched due the cross relaxation process due the absorption bands of Sm3+ around 1.5μm.

Er 3+ -doped micro-structured tellurite fiber: laser generation and optical gain

Optical results concerning the generation of laser and optical gain by using an Er3+-doped tellurite micro-structured fiber are reported for the first time. For this purpose a scheme that consist of two 980 nm diode pump lasers (simultaneously in the co-propagating and the counter-propagating directions) and short Er3+-doped tellurite micro-structured fibers (fabricated by using the stack-and-draw technique and a soft glass drawing tower) was used. The laser produced here was obtained within the range 1530 to 1565 nm, and the maximum optical gain obtained was higher than 8 dB.

Optical Amplifier based on a Er3+- doped Tellurite Microstructured Optical Fiber

Optical gain from 1530 up to 1570 nm by using an Er3+-doped tellurite microstructured fiber is presented. A maximum optical gain of ~27 dB at 1554 nm is obtained for a 980/1480 nm pump scheme.

Plasmonic structures fabricated by interference lithography for sensor applications

In this work we demonstrate the use of holographic lithography for generation of large area plasmonic periodic structures. Submicrometric array of holes, with different periods and thickness, were recorded in gold films, in areas of about 1 cm2, with homogeneity similar to that of samples recorded by Focused Ion Beam. In order to check the plasmonic properties, we measured the transmission spectra of the samples. The spectra exhibit the typical surface plasmon resonances (SPR) in the infrared whose position and width present the expected behavior with the period of the array and film thickness. The shift of the peak position with the permittivity of the surrounding medium demonstrates the feasebility of the sample as large area sensors.

Carbon Nanotube Doped Tellurite Glasses

In the past it was observed that buck ball doped glasses showed enhanced optical nonlinearities. However, carbon nanotubes are much more stable than buck ball and should be a better choice for that purpose. Therefore we decided to investigate the possibility to produce carbon nanotubes doped tellurite glasses and measured their optical nonlinearities. Tellurite glasses already have a larger nonlinearity compared to silica, and other, glasses. We produced TeO2-ZnO tellurite family glasses doped with multi wall Carbon Nanotube (CNT). The CNTs acquired from Carbolex were vigorously mechanically mixed with the tellurite glass precursors and melted in platinum crucible around 650°C in a controlled atmosphere inside an electrical induction furnace. We used the lowest temperature possible and controlled atmosphere to avoid the CNT oxidation. The glass melt was cast in a stainless steel and thermally treated at 300°C for 5 hours to relieve internal stresses. The samples were than cutted and polished to perform the optical characterization. We measured refractive index and thermo physical properties, such as vitreous transition Tg, crystallization onset Tx and melting Tf temperatures. Raman spectroscopy showed the possible presence of CNTs.

Waveguides produced by ion-exchange in Er3+-doped tellurite glass

This work reports the fabrication of planar and channel waveguides by Ag+ → Na+ ion exchange in an Er3+ doped tellurite glass with a composition of 75TeO2-2GeO2-10Na2O-12ZnO-1Er2O3 (mol %). The glass was chemically stable during the ion-exchange process. We have been able to produce single and multi-mode planar waveguides controlling the depths of the waveguides by varying ion-exchange temperatures, from 250 to 280 °C, and times, from 3 to 12 h. We also show preliminary results of channel waveguide fabrication with the same technique. The waveguide effective refractive index curves and attenuation (11 dB/cm) at 1536 nm were measured with a Metricom prism coupler. The Amplified Spontaneous Emission (ASE) spectra showed a 152 nm bandwidth when pumped with 120 mW laser pump at 980 nm.

Photothermal spectroscopic characterization in tellurite glasses codoped with rare-earth ions

Thermal Lens (TL) and spectroscopic characterizations were performed in 70TeO2-19WO3-7Na2O-4Nb2O5 (mol%) tellurite glasses. TL measurements were accomplished in Er3+ /Tm3+ co-doped tellurite glasses in function of the Tm2O3 concentration (0.4-1.6 x1020 ions/cm3). Fluorescence spectra at 488 nm showed that Er3+ /Tm3+ co-doped tellurite glasses present several emission bands between (500-1800) nm. However, the more intense emission bands correspond to the Tm3+ and Tm3+ transitions (4I13/2 → 4I15/2 and 3F4 → 3H6), respectively. The absolute nonradiative quantum efficiency (φ) was determined by TL method. Higher values of φ were obtained with the increase of Tm2O3 concentration inside of the Er3+/Tm3+ co-doped tellurite glasses. These results are corroborated by the Judd-Ofelt calculations.