摘要：We design an ultra-compact active hybrid plasmonic ring resonator for lasing applications at deep sub-wavelength scale. The combined contributions of hybrid plasmonic mode, circular-shaped cross section of nanowire, and ring resonator structure with round-trip whispering-gallery cavity, benefit reduced metallic absorption loss, tight mode confinement, enhanced cavity feedback, achieving high quality factor ( Q ), small mode volume ( V ), high Purcell factor ( Fp ), low threshold gain ( Gth ), and ultra-small footprint with sub-micron size. The performance dependence on the geometrical parameters, including gap height ( Hg ), cross section radius ( Rc ), and ring radius ( Rr ), are comprehensively analyzed, showing high Q factor of 1650 ( Hg = 30 nm, Rc = 100 nm, Rr = 800 nm), ultra-small mode volume of 0.0022 μm3 ( Hg = 5 nm, Rc = 100 nm, Rr = 800 nm), cut off of all photonic modes for pure plasmonic mode lasing with Rc Hg = 10 nm , Rr = 800 nm), maximum Purcell factor of 813 and minimum threshold gain of 1407 cm−1 ( Hg = 5 nm, Rc = 50 nm, Rr = 400 nm). The general design rules of the presented hybrid plasmonic ring resonator provide the potential to further extend ultra-compact sub-micron lasing applications (i.e. different lasing wavelength band) with proper choice of gain materials and geometric structures.
