Reducing polarization-dependent loss of silicon-on-insulator fiber to chip grating couplers

For many telecommunication applications, low polarization-dependent loss (PDL) operation is mandatory. On the silicon-on-insulator photonic wire platform, this can be achieved using polarization diversity configurations. However, as we show here, when using two-dimensional grating couplers for near vertical fiber input and output, the low PDL bandwidth is limited. We propose and demonstrate the use of a phase shifter in one of the arms of the polarization diversity circuit to effectively reduce PDL (0.15-dB PDL is shown) and increase the low PDL bandwidth

Implementation of surface gratings for reduced coupling noise in silicon-on-insulator circuits

Coupling light into a silicon-on-insulator photonic chip has always been the first hurdle to overcome when using photonic integrated circuits. For applications that require robust, low-noise performance, and high degree of multiplexing, flood illuminating an array of vertical grating couplers is a promising approach to couple input light into the chip waveguides. This technique provides a very high alignment tolerance and allows simultaneous excitation of multiple waveguides for rapid parallel readout. However, parasitic reflections of the coupled light on the chip substrate introduce interferences and limit the device performance. We investigate the use of grating structures implemented on the chip surface to limit these parasitic signals and demonstrate a significant reduction of the coupling noise

High-performance low-loss silicon-on-insulator microring resonators using TM-polarized light

Microring resonators on SOI are investigated for both orthogonal polarizations. By demonstrating low-loss (1.94dB/cm) microring resonators with an intrinsic Q up to 340000 we proof that using TM-polarized light enables high-performance filters

Silicon-on-insulator polarization rotating micro-ring resonator

We propose a novel micro-ring resonator which uses quasi-TE polarized light in the bus waveguide to excite the quasi-TM polarized modes in a micro-ring. An all-pass filter is demonstrated on Silicon-on-Insulator

Reflectionless grating coupling for silicon-on-insulator integrated circuits

We propose a novel grating coupler design which is inherently reflectionless by focusing the reflected light away from the entrance waveguide. The grating coupler design is investigated by means of 3D FDTD simulations