Silicon waveguides typically exhibit optical anisotropy, which leads to polarization correlation and single-polarization operations. This consequently creates a demand for polarization-control devices. This paper introduces a CMOS-compatible O-band reconfigurable TE/TM polarization rotator comprising two symmetrical polarization rotator–splitters and phase shifters. This configuration enables dynamic conversion of any linear polarization to its quadratic equivalent. Experimental results indicate that the reconfigurable polarization rotator exhibits an insertion loss of less than 1.5 dB. Furthermore, the bandwidth for a polarization extinction ratio beyond 15 dB exceeds 60 nm.

The electrical nonlinearity of silicon modulators based on reversed PN junctions was found to severely limit the linearity of the modulators. This effect, however, was inadvertently neglected in previous studies. Considering the electrical nonlinearity in simulation, a 32.2 dB degradation in the CDR3 (i.e., the suppression ratio between the fundamental signal and intermodulation distortion) of the modulator was observed at a modulation speed of 12 GHz, and the spurious free dynamic range was simultaneously degraded by 17.4 dB. It was also found that the linearity of the silicon modulator could be improved by reducing the series resistance of the PN junction. The frequency dependence of the linearity due to the electrical nonlinearity was also investigated.

A silicon-on-insulator-based adiabatic waveguide taper with a high coupling efficiency and small footprint is presented. The taper was designed to reduce the incidence of mode conversion to higher-order and radiation modes inside the waveguide. In connecting a 0.5-μm-wide output waveguide and a 12-μm-wide input waveguide of a grating coupler, a compact 120-μm-long taper was demonstrated, achieving a transmission of 98.3%. Previously, this transmission level could only be achieved using a conventional linear taper with a length of more than 300 μm.