Coaxial Mach-Zehnder Digital Strain Sensor Made from a Tapered Depressed Cladding Fiber.

An in-line digital optical sensor was proposed. It was built from a tapered depressed-cladding single-mode fiber and modeled as a coaxial Mach-Zehnder interferometer. The principle of operation of the optical digital sensor is based on the computation of the number of optical power transfer turning points (PTTP) from the transmission data of the component. Biconic tapers with high values of PTTP, high spectral resolution, high extinction ratio, and low insertion loss were modeled, fabricated, and characterized. As a proof of concept, an in-line digital strain sensor was fabricated and characterized. It presents a free spectral range of 1.3 nm, and produced 96 PTTP, at λ0 = 1.55 µm, under stretch of ΔL = 707 µm, therefore producing a digital resolution of 7.4 µm/PTTP. The sensor also produced a quasi-symmetric response to stretch and compression.

Inverse design of photonic structures using an artificial bee colony algorithm.

We adapted the standard artificial bee colony algorithm for a binary search space in order to optimize photonic structures. The artificial bee colony algorithm in conjunction with the finite element method is applied for maximizing photonic bandgaps of photonic crystals. The proposed approach is assessed by two case studies assuming 2D photonic crystals comprised of silicon and air in a triangular lattice. The crystals were optimized to present large photonic bandgaps. The artificial bee colony algorithm presented superior performance when compared with that of a standard genetic algorithm, demonstrating an interesting approach to be used on the inverse design or optimization of photonic structures.

High-resolution notch filters and diplexers based on SU-8 inverted rib waveguides.

We performed an end-to-end process, ranging from design, fabrication, and characterization of integrated polymeric optical devices under a mass production technology. Inverted rib waveguides formed by SU-8 photoresist deposited on top of full wafers, with trenches in silica, were used as a platform to implement such optical devices. Narrowband spectral filters based on microracetrack resonators and diplexers based on directional couplers, both with high extinction ratios, are demonstrated. Full wafers of those devices were processed in a complementary metal-oxide-semiconductor foundry's 150 mm-facility. We believe the results are promising for applications ranging from telecommunication components to sensing devices.

Site-Controlled Growth of Monolithic InGaAs/InP Quantum Well Nanopillar Lasers on Silicon.

In this Letter, we report the site-controlled growth of InP nanolasers on a silicon substrate with patterned SiO2 nanomasks by low-temperature metal-organic chemical vapor deposition, compatible with silicon complementary metal-oxide-semiconductor (CMOS) post-processing. A two-step growth procedure is presented to achieve smooth wurtzite faceting of vertical nanopillars. By incorporating InGaAs multiquantum wells, the nanopillar emission can be tuned over a wide spectral range. Enhanced quality factors of the intrinsic InP nanopillar cavities promote lasing at 0.87 and 1.21 µm, located within two important optical telecommunication bands. This is the first demonstration of a site-controlled III-V nanolaser monolithically integrated on silicon with a silicon-transparent emission wavelength, paving the way for energy-efficient on-chip optical links at typical telecommunication wavelengths.

Room-temperature Fabry-Perot resonances in suspended InGaAs/InP quantum-well nanopillars on a silicon substrate.

We present a new platform based on suspended III-V semiconductor nanopillars for direct integration of optoelectronic devices on a silicon substrate. Nanopillars grown in core-shell mode with InGaAs/InP quantum wells can support long-wavelength Fabry-Pérot resonances at room temperature with this novel configuration. Experimental results are demonstrated at a silicon-transparent wavelength of 1460 nm, facilitating integration with silicon platform.

Dielectric resonator antenna for applications in nanophotonics.

Optical nanoantennas, especially of the dipole type, have been theoretically and experimentally demonstrated by many research groups. Likewise, the plasmonic waveguides and optical circuits have experienced significant advances. In radio frequencies and microwaves a category of antenna known as dielectric resonator antenna (DRA), whose radiant element is a dielectric resonator (DR), has been designed for several applications, including satellite and radar systems. In this letter, we explore the possibilities and advantages to design nano DRAs (NDRAs), i. e., DRAs for nanophotonics applications. Numerical demonstrations showing the fundamental antenna parameters for a circular cylindrical NDRA type have been carried out for the short (S), conventional (C), and long (L) bands of the optical communication spectrum.