Ring-resonator-based wavelength filters

Microring resonators (MR) represent a class of filters with characteristics very similar to those of Fabry–Perot filters. However, they offer the advantage that the injected and reflected signals are separated in individual waveguides, and in addition, their design does not require any facets or gratings and is thus particularly simple. MRs evolved from the fields of fibre optic ring resonators and micron scale droplets. Their inherently small size (with typical diameters in the range between several to tens of micrometres), their filter characteristics and their potential for being used in complex and flexible configurations make these devices particularly attractive for integrated optics or VLSI photonics applications.\ud MRs for filter applications, delay lines, as add/drop multiplexers, and modulators will be covered in detail in this chapter, while other applications such as in optical sensing, in spectroscopy or for coherent light generation (MR lasers) are outside the scope of this chapter.\ud This chapter focuses primarily on 4-port microrings, while 2-port devices will play a minor role here and are covered in more detail in Chap. 9. The present chapter starts with design considerations, the functional behaviour, and key characteristics of a single microring resonator and continues with the design of cascaded MRs allowing the implementation of higher order filters. Finally, complex devices like add-drop filters, tuneable dispersion compensators, all-optical wavelength converters, and tuneable cross-connects are treated.\u

High speed electro optic polymer micro-ring resonator

An electro-optic polymer micro-ring resonator for high speed modulation was designed, realized and characterized. The design of layer-stack and electrodes was done such that modulation frequencies up till 1 GHz should be possible. The device consists of a ridge waveguide, defined in a negative photoresist (SU8), with a poled electro-optic polymeric (PMMA-DR1) ring-resonator vertically coupled to it. The complete layerstack is sandwiched between electrodes to apply an electric field over the ringresonator in order to shift its resonance wavelength. Electro optic modulation was measured up to 50 MHz limited by weak modulation depth. Optimizing the polingprocess will increase the modulation efficiency thereby making modulation frequencies of 1 GHz measurable

High speed polymer E-O modulator consisting of a MZI with a microring resonator

A Mach-Zehnder interferometer with an polymer electro-optic micro-ring resonator on one of its branches is realized in a polymer layerstack and characterized. Electro-optic coefficients of 10 pm/V and modulation frequencies of 1 GHz were measured

A novel high-speed polymeric EO modulator based on a combination of a microring resonator and an MZI

A Mach-Zehnder interferometer with an electrooptic polymer mircroring resonator adjacent to one of its branches is realized in a polymer layer stack. The microresonator is defined by reactive ion etching in the nonlinear PMMA-DR1 polymer and waveguide definition is done without etching, by using a negative photoresist (SU8) as waveguide layer. Electrooptic coefficients of 10 pm/V and modulation frequencies of 1 GHz were measured

'Aurora'-a time domain based meta-algorithm for the rapid simulation and design of complex optical circuits

A new simulation tool called ‘Aurora’, specifically developed to efficiently simulate highly complex optical devices such as OADMs and Routers based on (higher order)microring resonators, is presented. The meta-simulation algorithm used by Aurora creates a framework in which many different simulation algorithms can be properly combined rather than providing a simulation algorithm itself. The calculations of this program use a simple scheme based in the time domain from which the frequency response can easily be derived. Simulation results of a 4-port OADM and waveguide gratings show excellent agreement when compared to experimentally obtained measurement data and conventional simulation methods

Pricing Liquidity Risk with Heterogeneous Investment Horizons

We develop an asset pricing model with stochastic transaction costs and investors with heterogeneous horizons. Depending on their horizon, investors hold different sets of assets in equilibrium. This generates segmentation and spillover effects for expected returns, where the liquidity (risk) premium of illiquid assets is determined by investor horizons and the correlation between liquid and illiquid asset returns. We estimate our model for the cross-section of U.S. stock returns and find that it generates a good fit, mainly due to a combination of a substantial expected liquidity premium and segmentation effects, while the liquidity risk premium is small

Metal mask free dry-etching process for integrated optical devices applying highly photostabilized resist.

Photostabilization is a widely used post lithographic resist treatment process, which allows to harden the resist profile in order to maintain critical dimensions and to increase selectivity in subsequent process steps such as reactive ion etching. In this paper we present the optimization of deep UV-curing of 0,3-3.3 μm thick positive resist profiles followed by heat treatment up to 280 °C. The effectiveness of this resist treatment allows for metal mask free reactive ion etching with selectivity up to 6 for silicon structures, thermal silicon oxide and silicon oxynitride. This procedure is demonstrated by the results obtained in etching of various integrated optical structures

Multimode waveguides of Photodefinable epoxy for optical backplane applications

We developed photodefined, multimode-fiber compatible waveguides based on epoxies. These waveguides will be embedded in backplane PCB’s for optical interconnect applications using 850 nm VCSELs as light sources. Apart from very low loss, the material selection took into account, PCB compatibility and low yellowing due to high temperature processing (for PCB lamination and soldering). The waveguides showed losses < 0.06 dB/cm at 832 nm and 633 nm. Their loss increase after aging (1 hr at 185 °C) was limited to 0.04 dB/cm at 850 nm. Waveguides realized on FR-4 (epoxyfiberglass)PCB material are demonstrated