Compact surface-plasmon-polariton dichroic splitter with high splitting ratio based on three cascaded grooves
A compact surface-plasmon-polariton (SPP) dichroic splitter based on three cascaded nanogrooves of different dimensions is proposed. Photons normally incident on the dichroic splitting structure are converted to surface plasmons propagating to the left or right on the metal surface depending on the incident wavelength. A new operation principle is proposed to guide the structure design. Proof-of-principle demonstrations show that a remarkable property of high splitting ratios of 36.7 dB (right: left power flow contrast) at a splitting wavelength of 600 nm and 42.4 dB (left: right power flow contrast) at a wavelength of 800 nm is realized. The proposed design concept has very general applicability across other operating wavelengths, such as the communication bands (i.e., 1310 and 1550 nm).