We demonstrate a novel on-chip two-mode division multiplexing circuit using a tapered directional coupler-based TE(0)&TE(1) mode multiplexer and demultiplexer on the silicon-on-insulator platform. A low insertion loss (0.3 dB), low mode crosstalk (< -16 dB), wide bandwidth (~100 nm), and large fabrication tolerance (20 nm) are measured. An on-chip mode multiplexing experiment is carried out on the fabricated circuit with non return-to-zero (NRZ) on-off keying (OOK) signals at 40 Gbit/s. The experimental results show clear eye diagrams and moderate power penalty for both TE(0) and TE(1) modes.

/pdf/on-chip-two-mode-division-multiplexing-using-tapered-3q6lbg1gom.pdf

On-chip two-mode division multiplexing using tapered directional coupler-based mode multiplexer and demultiplexer

Photonic lanterns are made by adiabatically merging several single-mode cores into one multimode core. They provide low-loss interfaces between single-mode and multimode systems, where the precise optical mapping between cores and individual modes is unimportant.

The photonic lantern

During the last decade there has been a rapidly growing interest in integrated optical (IO) sensors, expecially because many of them principally allow for sensitive, real time, label-free-on-site measurements of the concentration of (bio-)chemical species. This review aims at giving an overview of the most relevant developments in this area. After a general introduction into the field of IO sensors for the chemical domain, relevant aspects of integrated optics and chemical sensing are presented in short. A large variety of IO sensing platforms are introduced and discussed: interferometers, resonators, coupling-based devices such as grating couplers and surface plasmon resonance based sensors and finally a new class of sensors based on chemically induced field profile changes. Strong and weak points of principle and of configuration based on these principles are indicated and the main performance data of the IO sensing platforms, especially the obtained resolution, are indicated. Best resolutions of the chemically induced refractive indices on the order of magnitude $10^{-6}-10^{-8}RIU$ can be obtained, corresponding to a resolution of $10^{-3}-10^{-5}$nm in the chemically induced growth of layer thickness of chemo-optical transducer materials. Depending on the anlalyte and the type of transduction layer chemical concentrations down to some ppb or some pg $ml^{-1}$can be determined. Several IO sensing systems are commercially available. Extension of individual sensors to sensor arrays is treated and finally an outlook for the future is given.

Integrated Optical sensors for the chemical domain

https://iopscience.iop.org/article/10.1088/0957-0233/17/8/R01/pdf

Integrated optical sensors for the chemical domain

Topics in Applied Physics is a well-established series of review books, each of which presents a comprehensive survey of a selected topic within the area of applied physics. Edited and written by leading research scientists in the field concerned, each volume contains review contributions covering the various aspects of the topic. Together these provide an overview of the state of the art in the respective field. Topics in Applied Physics is addressed to all scientists at universities and in industry who wish to obtain an overview and to keep abreast of advances in applied physics. The Managing Editors are open to any suggestions for topics coming from the community of applied physicists no matter what the field and encourage prospective book editors to approach them with ideas. 2015 Impact Factor: 0.889

Topics in applied physics

This paper describes the use of an integrated optical Bragg-reflector as a chemo-optical sensor. It is shown that these types of Bragg-reflectors for a wavelength of 630 nm can be realized with a bandwidth smaller than 0.2 nm in a optical channel waveguide. Measurements show that a refractive index change of the waveguide cladding of can be detected.

An integrated optical Bragg-reflector used as a chemo-optical sensor

It will he shown In this paper, that the mode conversion factor (MCF) as defined for Y-junctions, can be profitably applied for the design of three branch junctions for splitting the three lowest-order modes of a channel waveguide. Accordingly, these so-called mode-splitting /spl Psi/-junctions were designed for implementation in PECVD SiON-technology. Propagation calculations point to crosstalk levels well below -20 dB at 10-20 mm junction length. The produced /spl Psi/-junctions show crosstalk of less than -17 dB, mainly originating from the nonhomogeneity of the refractive indexes of the SiON layers.

/pdf/design-and-characterization-of-a-mode-splitting-spl-psi-3znndwtt3s.pdf

Design and characterization of a mode-splitting /spl Psi/-junction

It will be shown in this paper, that the mode conver- sion factor (MCF) as defined for Y-junctions, can be profitably the three lowest-order modes of a channel waveguide. Accord- ingly, these so-called mode-splitting Q-junctions were designed for implementation in PECVD SiON-technology. Propagation calculations point to crosstalk levels well below -20 dB at 10-20 mm junction length. The produced q-junctions show crosstalk Of at a desired crosstalk level. We have realized several mode- splitting junctions in SiON-technology using this strategy. butions over the branches, intensity profiles in the multimodal branch and the beat-pattern of light scattered out of that branch. The characterizations show that a @-junction with a intermodal crosstalk of less than - 17 dB has been realized. TO the best applied for the design of three branch junctions for These junctions were characterized by analyzing power distri-

Design and Characterizatio a Mode-Splitting Q-Junctio

/pdf/a-waveguide-material-for-integrated-optical-sensors-silicon-1os55fml1i.pdf

A waveguide material for integrated optical sensors: silicon oxynitride

The concept of device equivalence is introduced. In equivalent devices, the light propagation can be described by identically evolving modal expansions, resulting in identical power transfer ratios. By first applying this concept to a z-invariant structure with a low refractive-index contrast it is shown how a normalized coordinate space can be defined in which equivalent structures have exactly the same geometry. Subsequently it is shown how this normalized coordinate space can be defined for z-variant integrated optical devices, again provided that the lateral refractive-index contrast is small. This normalization makes it possible to perform numerical device simulations in normalized coordinate space, the results being applicable to a large set of equivalent devices. Furthermore, starting from a known design, it simplifies redesigning that device for use at another wavelength or using other materials significantly, the resulting device being equivalent to the original one. >

/pdf/device-equivalence-in-integrated-optics-5ae67uxzwc.pdf

J.H. Berends

Papers

An integrated optical Bragg-reflector used as a chemo-optical sensor

Design and characterization of a mode-splitting /spl Psi/-junction

Design and Characterizatio a Mode-Splitting Q-Junctio

A waveguide material for integrated optical sensors: silicon oxynitride

Device equivalence in integrated optics