High-Efficiency Nanoplasmonic Wavelength Filters Based on MIM Waveguides

Two ultra-compact nanoplasmonic wavelength filters based on stepped impedance low-pass prototype filter in metal-insulator-metal waveguides are suggested. The transmission and reflection efficiency of both high-pass wavelength and long-wavelength cutoff filter is more than 93%, respectively. Simulation results reveal that similar to the tunability of the structure's transmission spectrum by changing the thickness of the insulator medium, the variations of the width of steps' discontinuities in the high-pass device not only provide an effective method to adjust the transmission peak/cutoff wavelength position, but also give rise to the structure to realize a long-wavelength cutoff filter. On the contrary, modifying the value of aperture length in the proposed long-wavelength cutoff filter gives the capability to control the cutoff wavelength. Moreover, changing the insulator medium to silica converts the device as a dual band bandpass filter at the wavelengths of 1300 and 1550 nm with efficiency of more than 85.2% and 78.1%, respectively. Hence, because of their excellent performance, features, and optimized size, they may have applications in high density photonic integrated circuits.