David J. DeShazer

Development of Versatile Polymer Waveguide Flex Technology for Use in Optical Interconnects

We report on the implementation of novel flexible polymer waveguide interconnects. They are based on newly developed mechanically flexible low-loss silicone waveguides. In addition to meeting the generic requirements of rigid waveguide interconnects, several flex-material challenges were mastered: a) mechanical flexibility permitting waveguide flexing down to radii of 1.0 mm without cracking; b) minimization of waveguide curling induced by the CTE mismatch between flex substrates and polymer layers to enable assembly and connectorization; c) greatly improved cladding adhesion on standard PCB flex substrates, such as polyimide; and d) high environmental stability despite the reduced polymer cross-linking required for better mechanical flexibility. The new waveguides exhibit excellent stability in damp heat (2000 h in 85°C/85% rH) and under thermal shock (500 cycles from -40° to +120°C), and lead-free solder reflow up to 260°C. Using the newly engineered “Dow Corning WG-1017 Optical Waveguide Clad Dev Sample” and the established “Dow Corning WG-1010 Optical Waveguide Core”, we were able to develop a manufacturing process suitable for large areas and offering high process control and stability to produce waveguides having optical loss values of less than 0.05 dB/cm at 850 nm VCSEL wavelength and fulfilling requirements (a) to (d) above. We describe this manufacturing process and how we have overcome the material challenges mentioned. Furthermore, we present characterization and manufacturing results, show demonstrators, and outline the potential of flexible waveguides as versatile electro-optic assembly platform.

Flexible, stable, and easily processable optical silicones for low loss polymer waveguides

Photopatternable optical silicone materials have been developed that can be fabricated into flexible polymer waveguides using conventional film processing and photolithography techniques. Waveguides designed for multimode applications have demonstrated loss of 0.05 dB/cm at 850 nm. These waveguides have proven stable in 85% relative humidity and 85°C storage conditions for greater than 2000 hours to date with no degradation in optical performance. Further, this polymer waveguide system has shown sufficient adhesion to flexible polyimide substrates without any curling, and passed bending tests to a 1 mm radius without damage.

Integrated optical and electronic interconnect PCB manufacturing research

Purpose – The purpose of this paper is to provide an overview of the research in a project aimed at developing manufacturing techniques for integrated optical and electronic interconnect printed circuit boards (OPCB) including the motivation for this research, the progress, the achievements and the interactions between the partners.Design/methodology/approach – Several polymer waveguide fabrication methods were developed including direct laser write, laser ablation and inkjet printing. Polymer formulations were developed to suit the fabrication methods. Computer‐aided design (CAD) tools were developed and waveguide layout design rules were established. The CAD tools were used to lay out a complex backplane interconnect pattern to meet practical demanding specifications for use in a system demonstrator.Findings – Novel polymer formulations for polyacrylate enable faster writing times for laser direct write fabrication. Control of the fabrication parameters enables inkjet printing of polysiloxane waveguides...

Experimental observation of noise-induced synchronization of bursting dynamical systems

Can bursts in dynamical systems be synchronized by a weak, common, noise background? We observe large, uncorrelated bursts of intensity fluctuations in two almost identical erbium-doped fiber ring lasers, initiated by common injection of a weak, constant intensity optical signal. Significant synchronization of the bursts is obtained for noise and sinusoidal modulation of the injected light intensity. Measurements of the burst statistics and synchronization are presented.

PHASE SYNCHRONIZATION IN A MODULATED CHAOTIC LASER ARRAY

Phase synchronization and entrainment of a linear array of loss modulated Nd:YAG lasers are experimentally investigated. The temporally shifting nature of phase synchronization with increasing modulation depth is studied. Chaotic intensity dynamics changes dramatically with increasing modulation, and exhibit entrainment to the modulation signal. Frequency filtered phase variables, defined from the laser intensity time series, uncover phenomena of phase synchronization and competition for phase synchronization that are otherwise hidden.

Polymer waveguide based optical backplanes and electro-optical assembly technology for computing applications

We report on recent developments of our board-level optical interconnect technology towards polymer waveguide flexes and on the adaption of connectorization and electro-optical assembly methods to be used in optical backplanes and high-density optical subassemblies.

Stochastic bursting due to frequency drift in an injected fibre laser

The joint influence of stochastic frequency drift and optical injection on the dynamical behaviour of a rate-equation laser model is studied. When the autocorrelation time of the frequency fluctuations is larger than the typical timescales of the systems dynamics, and the amplitude of the frequency drift is larger than the injection locking range, the laser exhibits bursting behaviour at irregular times, each burst being followed by relaxation oscillations towards the unlocked state. The conditions under which this type of phenomenon occurs are fulfilled in fibre lasers. Accordingly, numerical simulation results of the model agree satisfactorily with the experimentally observed behaviour of an injected fibre ring laser.

Noise Induced Burst Synchronization in Fiber Ring Lasers

Can bursts in dynamical systems be synchronized by a weak, common, noise background? We observe large, uncorrelated bursts of intensity fluctuations in two nearly identical erbium‐doped fiber ring lasers, initiated by common injection of a weak, constant intensity optical signal. The magnitude and frequency of the chaotic bursting depends upon the injected wavelength and intensity. Significant synchronization of the bursts is obtained for noise and sinusoidal modulation of the injected light intensity. The degree of synchronization is quantified using an envelope constructed from the amplitude of the analytic signal, and is studied as a function of the noise variance. The noise induced burst synchronization can be viewed as a form of generalized synchronization of the fiber ring lasers to the common modulation signal, though no obvious relationship between the drive and response dynamics is directly observed.

Polarization independent and low loss laser written polysiloxane interconnect building blocks

Single-mode polysiloxane based waveguides and directional couplers, key optical interconnect building blocks, were fabricated using direct laser writing. Key performance parameters include polarization independent propagation loss of 0.23 dB/cm and a possible wafer scale fabrication.

Stochastic modeling of bursting dynamics in an injected fiber laser

We study the effect of optical injection on the dynamical behavior of a laser whose frequency drifts randomly in time. When the autocorrelation time of these random fluctuations is larger than the ty ical time scales of the system dynamics,and the range of the frequency drift is larger than the injection locking range,the laser exhibits bursting behavior at irregular times,each burst being followed by relaxation oscillations towards the unlocked state. Numerical results from a simple model agree satisfactorily with the experimentally observed behavior of an injected fiber ring laser.