Straight and S-bend rib waveguide structures with a novel design have been fabricated and characterized on a silicon-on-insulator (SOI) platform. For a typical straight rib waveguide, the single-mode waveguide at lambda approximately 1550 nm has been verified by measuring the near-field output with an IR camera, and a nearly polarization-independent mode size is found to be approximately 10 microm x 4.5 microm. The waveguide loss has been estimated from low-finesse Fabry-Perot transmission characteristics, and a typical value of approximately 0.5 dB/cm is obtained. It is also shown experimentally that the bending radius of an asymmetrically etched S-bend waveguide can be ten times smaller than that of conventional symmetrically etched S-bend waveguides for similar optical losses. These bend waveguides (bending radii of approximately 1500 microm) are found to be low loss (<2.5 dB) and nearly polarization independent.
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http://dx.doi.org/10.1364/AO.48.00G125 | DOI Listing |
We propose and demonstrate experimentally an electro-optic (EO) and thermo-optic (TO) tunable wavelength filter with band-rejection and band-pass dual-function. Our proposed filter is based on a long-period waveguide grating (LPWG) formed on a lithium niobate on insulator (LNOI) rib waveguide with a channel-shaped polymer cladding waveguide. The LPWG formed on the surface of the LNOI core enables efficient mode coupling between the two fundamental modes of the LNOI waveguide and the polymer cladding waveguide and hence dual-function filtering.
View Article and Find Full Text PDFThe accurate determination of the effective and group refractive indices (n and n) of optical waveguides as a function of wavelength is of critical importance to the design of photonic integrated circuits (PICs). This paper demonstrates the extraction of the two parameters of silicon-on-insulator (SOI) rib waveguides using the transmission spectra of two racetrack micro-ring resonators (MRRs) with different perimeters. The extracted n and n exhibit an uncertainty of approximately 10.
View Article and Find Full Text PDFSamples of dielectric optical waveguides of rib or strip type in thin-film lithium niobate (TFLN) technology are characterized with respect to their optical loss using the Fabry-Pérot method. Attributing the losses mainly to sidewall roughness, we employ a simple perturbational procedure, based on rigorously computed mode profiles of idealized channels, to estimate the attenuation for waveguides with different cross sections. A single fit parameter suffices for an adequate modelling of the effect of the waveguide geometry on the loss levels.
View Article and Find Full Text PDFThis article reports a novel design of a compact tunable resonance filter with a highly extinguished and ultra-broad out-of-band rejection for on-chip amplified spontaneous noise suppression from pump lasers highly demanding for generating pure/entangled photon pairs via χ process in a CMOS compatible silicon photonics technology platform. The proposed device is designed with two identically apodized distributed grating structures for guided Fabry-Perot resonant transmissions in a silicon-on-insulator rib waveguide structure. The device design parameters are optimized by theoretical simulation for a low insertion loss singly-resonant transmission peak at a desired wavelength.
View Article and Find Full Text PDFACS Appl Mater Interfaces
July 2024
Ecole Polytechnique Federale de Lausanne, 1015 Lausanne, Switzerland.
Formation of laser-induced periodic surface structures (LIPSS) is known as a fast and robust method of functionalization of material surfaces. Of particular interest are LIPSS that manifest as periodic modulation of phase state of the material, as it implies reversibility of phase modification that constitute rewritable LIPSS, and recently was demonstrated for chalcogenide phase change materials (PCMs). Due to remarkable properties of chalcogenide PCMs─nonvolatality, prominent optical contrast and ns switching speed─such novel phase change LIPSS hold potential for exciting applications in all-optical tunable photonics.
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