Broadband Plasmonic Absorber for Photonic Integrated Circuits

Surface plasmon polaritons losses have long been considered as a fatal shortcoming of plasmonics based information transport. Here, we propose a plasmonic absorber utilizing this shortcoming to absorb the stray light in photonic integrated circuits (PICs). Benefiting from adiabatic mode evolution, its performance is insensitive to incident wavelength with bandwidth larger than 300 nm, and is robust against surrounding environment and temperature. Besides, the use of metal enables it to be very compact and beneficial to thermal dissipation. With this 40-m-long absorber, the absorption efficiency can be over 99.8% at 1550 nm, with both the reflectivity and transmittance reduced to < 0.1%. Such a device may find various applications in PICs, to eliminate the residual strong pump laser or stray light.