Ultra-compact graphene plasmonic filter integrated in a waveguide<xref rid="cpb_27_9_094101fn1" ref-type="fn">*</xref><fn id="cpb_27_9_094101fn1"><label>*</label><p>Project supported by the National Basic Key Research Program of China (Grant No. 2015CB932400), the National Key Research and Development Program of China (Grant No. 2016YFA0201600), the National Natural Science Foundation of China (Grant Nos. 51372045, 11504063, and 11674073), the Key Program of the Bureau of Frontier Sciences and Education, Chinese Academy of Sciences (Grant No. QYZDBSSW- SLH021), and the Science and Technology Projects of Beijing City, China (Grant No. Z161100002116016).</p></fn>

Ultra-compact graphene plasmonic filter integrated in a waveguide**

Project supported by the National Basic Key Research Program of China (Grant No. 2015CB932400), the National Key Research and Development Program of China (Grant No. 2016YFA0201600), the National Natural Science Foundation of China (Grant Nos. 51372045, 11504063, and 11674073), the Key Program of the Bureau of Frontier Sciences and Education, Chinese Academy of Sciences (Grant No. QYZDBSSW- SLH021), and the Science and Technology Projects of Beijing City, China (Grant No. Z161100002116016).

Liao Baoxin^{1, 2}, Guo Xiangdong^{1, 2}, Hu Hai^{1, 2}, Liu Ning^{1, 2}, Chen Ke^{1, 2}, Yang Xiaoxia^{1, 2, ‡}, Dai Qing^{1, 2, †}

(color online) (a) Graphene plasmon (GP) transmission spectra on graphene ribbon (green), filter (blue), and broken graphene ribbon (orange). l = 40 nm, d = 40 nm, W = 50 nm, and E_F = 0.35 eV. Red dots denote the coupled mode theory results for the filter. Insets are the sketch maps of the graphene waveguide. (b)–(d) E_z field distribution around the filter at 19.41 THz (peak 1), 27.26 THz (dip), and 31.69 THz (peak 2). (e) H_z field distribution at 31.69 THz (peak 2). The cavity can be regarded as a ring resonator, and L_i and L_o are the inner and outer perimeters of the cavity. τ_s stands for scattering loss between the waveguide and cavity. E_s represents the amplitudes of the electric field of the resonant modes around the hole.