Nonreciprocal isolator based on a plasmonic magneto-optical resonator

A dichromic isolator based on a magneto-optical (MO) ring resonator with a silver disk embedded in its center is proposed and investigated. By calculating the dispersion relation, the nonreciprocal phase shift of plasmonic wave is significant in the MO ring at near infrared frequencies. The nonreciprocity of the isolator can be adjusted by the width of the ring, which reaches its maximum value when the width is approximately 0.11 times the working wavelength. Thus, good isolation performance with two working frequencies in opposite directions is realized. The isolation ratio of our structure reaches up to 20.1 dB, and the insertion loss is as low as 0.89 dB at ∼218 THz. The working frequencies of the dichromic isolator can be modulated by the width of ring. Our results show suitable applications in integrated one-way devices.