Parastesh Pirasteh

Optical loss study of porous silicon and oxidized porous silicon planar waveguides

We have studied optical losses as a function of the wavelength for planar waveguides formed from porous silicon or oxidized porous silicon. Scattered light from the surface of samples was also observed. This observation reveals the influence of porous silicon dissolution front fluctuations called waviness on propagation. After oxidation, the measured losses decreased strongly and attained a value equal to 0.5 dB/cm in the near infrared. Surface and volume scattering losses were modeled in order to determine their principal contributions to overall losses. For porous silicon waveguides obtained from a P+ silicon substrate, the losses were mainly due to absorption by the material; whereas, for oxidized porous silicon waveguides, the principal contribution depends on the used wavelength. In the visible spectrum, losses due to volume scattering were predominant while in the near infrared, surface scattering was responsible for most of the losses.

Optical amplification of Pr3+ -doped ZBLA channel waveguides for visible Laser emission.

We report on the first observation of optical signal amplification in the visible range into praseodymium doped ZBLA glass channel waveguides obtained by ion exchange. Up to 30% signal amplification was obtained at 639 nm. This result shows the potential of rare earth doped fluoride glasses in the form of channel waveguides for integrated solid state visible laser sources.

Guided photoluminescence study of Nd-doped silicon rich silicon oxide and silicon rich silicon nitride waveguides

Planar waveguides made of Nd3+-doped silicon rich silicon oxide (SRSO) and silicon rich silicon nitride (SRSN) have been fabricated by reactive magnetron sputtering and characterized with special emphasis on the comparison of the guided photoluminescence (PL) properties of these two matrices. Guided fluorescence excited by top surface pumping at 488 nm on planar waveguides was measured as a function of the distance between the excitation area and the output of the waveguide, as well as a function of the pump power density. The PL intensity increased linearly with pump power without any saturation even at high power. The linear intensity increase of the Nd3+ guided PL under a non-resonant excitation (488 nm) confirms the efficient coupling between either Si-np and rare-earth ions for SRSO or radiative defects and rare earth ions for SRSN. The guided fluorescences at 945 and 1100 nm were observed until 4 mm and 8 mm of the output of the waveguide for Nd3+ doped SRSO and SRSN waveguides, respectively. The gu...

Modal Analysis of Graded-Index Porous Silicon Slab Waveguides

We investigate the modal properties, for TE polarization, of graded-index porous silicon slab waveguides with linearly varying dielectric permittivity. Using transfer matrix formalism, we derive all-analytical expressions, in terms of special functions of the Bessel class, for the propagation constant and the transverse profile of each mode.

High sensitivity optical biosensor based on polymer materials and using the Vernier effect

We demonstrate the fabrication of a Vernier effect SU8/PMATRIFE polymer optical biosensor with high homogeneous sensitivity using a standard photolithography process. The sensor is based on one micro-resonator embedded on each arm of a Mach-Zehnder interferometer. Measurements are based on the refractive index variation of the optical waveguide superstrate with different concentrations of glucose solutions. The sensitivity of the sensor has been measured as 17558 nm/RIU and the limit of detection has been estimated to 1.1.10-6 RIU.

Study of Optimized Coupling Based on Micro-lensed Fibers for Fibers and Photonic Integrated Circuits in the Framework of Telecommunications and Sensing Applications

We demonstrate the interest of expanded beam microlenses (around 55 µm of mode field diameter) to relax positioning tolerances and to decrease reflectance in single mode fiber to fiber interconnections . We also point out the interest of micro-lenses of very small mode field diameter (around 2 µm) to improve coupling efficiency in specialty fibers and integrated waveguides for non linear effects based functions and for sensors applications at a wavelength of 1.55 µm.