Mode-division multiplexing (MDM) is an emerging multiple-input multiple-output method, utilizing multimode waveguides to increase channel numbers. In the past, silicon-on-insulator (SOI) devices have been primarily focused on single-mode waveguides. We present the design and fabrication of a two-mode SOI ring resonator for MDM systems. By optimizing the device parameters, we have ensured that each mode is treated equally within the ring. Using adiabatic Bezier curves in the ring bends, our ring demonstrated a signal-to-crosstalk ratio above 18 dB for both modes at the through and drop ports. We conclude that the ring resonator has the potential for filtering and switching for MDM systems on SOI.

A polymer light-emitting electrochemical cell (LEC) is a solid-state polymer device operating on in situ electrochemical doping and the formation of a light-emitting polymer p-n junction. Electrochemical doping of the luminescence polymer quenches the photoluminescence. The chemical potential difference between the p- and n-doped regions creates a built-in potential/field in the junction region, which can be probed by measuring the optical beam induced current (OBIC). In this study, the OBIC and photoluminescence profiles of the LEC have been simultaneously measured by scanning a focused light beam across a large planar LEC that has been turned on and cooled to freeze the doping profile. The photoluminescence intensity undergoes a sharp transition between the p- and n-doped regions. The OBIC photocurrent is only observed in the transition region that is narrower than the width of the excitation beam, which is about 35 μm. The results depict a static planar polymer p-n junction with a built-in field pointing from n to p. The electrode interface and the neutral regions do not produce a measurable photocurrent.

Direct laser writing (DLW) is a versatile materials processing technique often applied to device prototyping. However, a fast and cost effective DLW process for fabricating three-dimensional (3D) conductor-insulator composites has yet to be demonstrated. In this work, polyimide (PI) is established as a viable platform for creating 3D graphitic circuits through ultrafast DLW. Under optimized processing conditions, graphitic material with a resistivity of 6 Ω·cm was formed in the laser irradiated regions. A thermal and microstructural material model is proposed for the non-linear DLW process and its graphitic products. The process is demonstrated to be an inexpensive and rapid technique for creating electrical contacts to nanoscale components. Future applications of the technique range from nanowire power generation to 3D integrated photonic and electronic devices.0a The

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