Pengjun Wang

Mode multi/demultiplexer based on cascaded asymmetric Y-junctions.

A mode-(de)multiplexer with low loss and large spectral bandwidth is proposed. The device is designed by utilizing a structure with cascaded asymmetric Y-junctions. By carefully controlling the widths of the wide and narrow arms of the Y-junctions, the fundamental mode of a narrow arm excites the higher-order mode of its stem in the multiplexing case, and a high-order mode of the stem separated from other lower-order modes evolves into the fundamental mode of the narrow arm in the demultiplexing case. As an example, a 1 × 4 mode-(de)multiplexer is analyzed by using the beam propagation method. Simulation results show the demultiplexed crosstalk is lower than -21.8 dB, under a common spectral bandwidth of 140 nm. The insertion loss is negligible.

Silicon three-mode (de)multiplexer based on cascaded asymmetric Y junctions

A three-mode (de)multiplexer based on two cascaded asymmetric Y junctions is proposed and experimentally demonstrated on a silicon-on-insulator platform for mode-division multiplexing applications. Within a bandwidth from 1537 to 1566 nm, the best demultiplexing crosstalk of the fabricated device, composed of a three-mode multiplexer, a multimode straight waveguide, and a three-mode demultiplexer, is up to -31.5u2009u2009dB, while in the worst case it is -9.7u2009u2009dB. The measured maximum insertion loss is about 5.7 dB at a wavelength of 1550 nm. The mode crosstalk and insertion loss can be further improved by high-quality fabrication processes.

Optical Mode Interleaver Based on the Asymmetric Multimode Y Junction

An optical mode interleaver (OMIL) based on the asymmetric multimode Y junction is proposed for realizing flexible selection of group of modes in mode-division multiplexing optical network. The odd and even modes of the stem can be sorted by carefully controlling the widths of the narrow and wide arms according to the constraint conditions of the propagation constants. A four-mode OMIL is analyzed as an example using the beam propagation method. The device is able to realize a low excess loss of <;0.13 dB, a high mode extinction ratio that exceeded 28.4 dB, and a mode crosstalk lower than -25.5 dB over a common spectral bandwidth of 210 nm.

Design of a Flexible-Grid 1 × 2 Wavelength-Selective Switch Using Silicon Microring Resonators

In this paper, a compact integrated flexible-grid 1 × 2 wavelength-selective switch is proposed. The device is designed by utilizing a structure with nine reconfigurable add-drop silicon microring resonators. Using thermal tuning, the transmission spectra of silicon microring resonators are coherently combined to provide adjustable bandwidths as desired. The operation principle and detailed analysis of the designed device are presented. Calculation results show the bandwidth tuning for the spectrum with the large bandwidth varies from 0.56 to 4.09 nm and the bandwidth tuning for the spectrum with the moderate bandwidth ranges from 0.38 to 2.64 nm. The integrated flexible-grid 1 × 2 wavelength-selective switch with the maximum bandwidth tunability has a maximum crosstalk of −11.5 dB.