High Q-factor plasmonic filter based on MIM structures and its application in the design of a dual band demultiplexer for optical communication wavelengths
Fatemeh Abdolalipour, Maryam Pourmahyabadi
Abstract
One of the key components in optical integrated circuits is bandpass filters. In this article, a scheme of plasmonic filters consisting of a nanodisk cavity coupled with two <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mi>T</mml:mi> </mml:mrow> </mml:math> -shaped metal–insulator–metal (MIM) waveguides is presented. The nanodisk cavity is in a square or rectangular shape. The effects of the geometrical parameters variations on the transmission spectrum are investigated. The results of the numerical simulation analysis indicate that the perfect transmission peak can be achieved by optimizing the structure parameters. Hence, the appropriate dimensions of this structure for operating in the optical communication wavelength range (from <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mi>O</mml:mi> </mml:mrow> </mml:math> to <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mi>L</mml:mi> </mml:mrow> </mml:math> bands) are obtained. Also, the proposed filter exhibits the transmission peak of 0.99 and the high quality factors ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mi>Q</mml:mi> </mml:mrow> </mml:math> -factors) of 91 and 109.25 at the wavelengths of 1550 nm and 1310 nm, respectively. In addition, a design of two-channel demultiplexer is presented, in which the waveguides are connected by <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mi>T</mml:mi> </mml:mrow> </mml:math> or <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mi>Y</mml:mi> </mml:mrow> </mml:math> junctions. The results show that the proposed structure exhibits the transmission peaks of 0.8 and 0.67 and the <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mi>Q</mml:mi> </mml:mrow> </mml:math> -factors of 65 and 103.3 at the resonance wavelengths of 1310 nm and 1550 nm, respectively.