A. Borreman

Box-Shaped Dielectric Waveguides: A New Concept in Integrated Optics?

A novel class of optical waveguides with a box-shaped cross section consisting of a low-index inner material surrounded by a thin high-index coating layer is presented. This original multilayered structure widens the traditional concept of index contrast for dielectric waveguides toward a more general concept of effective index contrast, which can be artificially tailored over a continuous range by properly choosing the thickness of the outer high-index layers. An electromagnetic analysis is reported, which shows that the transverse electric and transverse magnetic modes are spatially confined in different regions of the cross section and exhibit an almost 90°C rotational symmetry. Such unusual field distribution is demonstrated to open the way to new intriguing properties with respect to conventional waveguides. Design criteria are provided into details, which mainly focus on the polarization dependence of the waveguide on geometrical parameters. The possibility of achieving single-mode waveguides with either zero or high birefringence is discussed, and the bending capabilities are compared to conventional waveguides. The feasibility of the proposed waveguide is demonstrated by the realization of prototypal samples that are fabricated by using the emerging CMOS- compatible Si3N4-SiO2 TriPleX technology. An exhaustive experimental characterization is reported, which shows propagation loss as low as state-of-the-art low-index-contrast waveguides (< 0.1 dB/cm) together with enhanced flexibility in the optimization of polarization sensitivity and confirms the high potentialities of the proposed waveguides for large-scale integrated optics.

Single-Chip Ring Resonator-Based 1

Optical ring resonators (ORRs) are good candidates to provide continuously tunable delay in optical beam forming networks (OBFNs) for phased array antenna systems. Delay and splitting/combining elements can be integrated on a single optical chip to form an OBFN. A state-of-the-art ring resonator-based 1times 8 OBFN chip has been fabricated in complementary metal-oxide-semiconductor-compatible waveguide technology. A binary tree topology is used for the network such that a different number of ORRs is cascaded for delay generation at each output. In this letter, the principle of operation is explained and demonstrated by presenting some measurement results on the 1times 8 OBFN chip.

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We report experiments which show evidence that stimulated emission at 863 nm takes place in hybrid monomode Si3N4 waveguides where LaF3 :Nd nanoparticle-doped polymethylmethacrylate (PMMA) was used as a top cladding material. Furthermore, optical gain at 1319 nm in LaF3:Nd nanoparticle dispersed PMMA s0.1 dB/cmd and photodefinable epoxy (Microchem SU-8) multimode waveguides has been observed at pump powers below 10 mW. This class of composite materials based on polymers with dispersed nanoparticles shows promising properties for planar optical amplifiers. Simulation showed that optical gain in the order of 10 dB can be achieved at 100 mW pump power in a 20 cm long monomode waveguide.

8 Optical Beam Forming Network in CMOS-Compatible Waveguide Technology

A novel beam steering mechanism for a phased array antenna receiver system is introduced. The core of the system is a ring resonator-based integrated optical beam forming network chip. Its principles are explained and demonstrated by presenting some measurement results. The system architecture around the chip is based on a combination of frequency down conversion, filter-based optical single sideband modulation and balanced coherent detection. It is proven that such an architecture has significant advantages with respect to a straightforward architecture using double sideband modulation and direct detection, namely relaxed bandwidth requirements on the optical modulators and detectors, reduced complexity and optical losses of the beam forming chip, and enhanced dynamic range

Stimulated emission and optical gain in LaF3:Nd nanoparticle-doped polymer-based waveguides

Optical ring resonators (ORRs) can be used as continuously tunable delay elements in a beam forming network for a phased-array antenna system. The bandwidth of such delay elements can be enhanced by cascading multiple ORRs. When delays and splitting/combining circuitry are integrated in one optical circuit, an optical beam forming network (OBFN) is obtained. In this paper, the principles of optical beam forming using ORRs are explained and demonstrated, by presenting measurements on a 1times4 OBFN chip, realized in LPCVD waveguide technology. To our knowledge, this is the first single-chip demonstration of continuous optical beam forming

Phased Array Antenna Steering Using a Ring Resonator-Based Optical Beam Forming Network

A novel optical beamformer system for phased array transmit antennas is proposed and experimentally demonstrated. It is based on an optical IM/DD link through a ring resonator-based optical beam forming network chip.