Plasmonic Bidirectional/Unidirectional Wavelength Splitter Based on Metal-Dielectric-Metal Waveguides

Abstract

A plasmonic bidirectional/unidirectional wavelength splitter based on asymmetric metal-dielectric-metal (MDM) waveguides is proposed. In the splitter, owing to the interference effects caused by the unequal phase delays from the two asymmetric arms of MDM waveguides, surface plasmon polaritons (SPPs) will only transmit through the output port that is close to the arm where constructive interference arises. The transmission wavelengths can be linearly modulated by changing the lengths of the arms. Since two different SPP modes are obtained in two output ports, respectively, the structure can act as a bidirectional wavelength splitter. Interestingly, both SPP modes can be manipulated to transmit through the same port by adding a notch in one arm. In this case, the notch must simultaneously locate at the anti-node and at the node of the magnetic fields of two SPP modes respectively. As a result, additional phase delay for the specific mode will be produced by the notch, but without any impact on the other mode. Then, the propagation directions of both modes will turn to be identical. High transmission and high cross-talk isolation are investigated for all the cases by using the finite-difference time-domain method.

Plasmonic Mach-Zehnder Interferometers Based on Air-Gap Couplers

“…The potential of using MDM plasmonic waveguides in many optical devices has been explored. MDM plasmonic waveguides have been used in several applications, including power splitters [5][6][7][8][9][10][11], Mach-Zehnder interferometers [12][13][14][15], filters [16][17][18][19], switches [20][21][22][23], sensors [24][25][26][27], wavelength division multiplexers [28][29][30], solar cells [31][32][33][34], and photovoltaic devices [35][36][37][38]. To design high-performance nanoscale plasmonic devices and increase the information processing speed, hybrid integration of plasmonic and CDW is required.…”