In order to reduce the size of the device and realize the ultrafast response time and dynamic tunableness, the single-band and dual-band plasmon induced transparency (PIT) effect are investigated based on graphene nanoribbon waveguide side-coupled rectangle cavity. The slow light properties of the model are analyzed numerically and theoretically by coupled mode theory and finite difference time domain method. With controlling the chemical potential of the graphene rectangle cavity, the tunability of the resonant wavelength and the transmission peak can be achieved simultaneously in single-band and dual-band PIT model. As the chemical potential of graphene increases, the resonant wavelength of each transmission window of PIT effect decreases gradually and presents the blue shift. In addition, through dynamically tuning the resonant wavelength of the graphene rectangle cavity, when the chemical potential of the graphene rectangle cavity increases from 0.41 to 0.44 eV, the group index of single PIT system is controlled to be between 79.2 and 28.3, and the tunable bandwidth is 477 nm. Moreover, the group index of dual PIT system is controlled to be between 143.2 and 108.6 when the chemical potentials of graphene rectangle cavities 1, 2, and 3 are 0.39–0.42 eV, 0.40–0.43 eV, and 0.41–0.44 eV, respectively. The size of the entire PIT structure is <0.5 μm2. The research results here in this work are of reference significance in designing and fabricating the optical sensors, optical filters, slow light and light storage devices with ultrafast, ultracompact and dynamic tunableness.

In order to reduce the power and realize ultrafast response time, a plasmonic waveguide system based on two stub cavities side-coupled is designed, and a plasmon induced transparency effect is investigated. The plasmonic waveguide based on graphene-Ag composite material structures is tuned by the optical Kerr effect. An ultrafast response time of the order of 1 ps is reached. With dynamically tuning the propagation phase of the plasmonic waveguide, n-phase shift of the transmission spectrum in the plasmon induced transparency system is achieved under excitation of a pump light with an intensity as low as 5.83 MW/cm(2). The pump light intensity is reduced by adopting graphene-Ag composite material structures. The reason is that the optical Kerr effect is enhanced by the local electromagnetic field of surface plasmon polaritons, the slow light of the plasmon induced transparency effect and the plasmonic waveguide based on graphene-Ag composite material structures with giant effective Kerr nonlinear coefficient. The tunable bandwidth of about 40 nm is obtained. The group delay is controlled between 0.15 ps and 0.85 ps. Moreover, for the indirect coupling between two stub cavities or the phase coupling scheme, the phase shift multiplication effect of the plasmon induced transparency effect is found. The theoretical results are in good agreement with finite difference time domain simulations. Research results are of reference significance in design and fabrication of nanoscale integration plasmonic photonic devices with low power consumption and ultrafast nonlinear responses.

An ultrafast and low-power slow light tuning mechanism based on plasmon-induced transparency (PIT) for two disk cavities aperture-coupled to a metal-dielectric-metal plasmonic waveguide system is investigated numerically and analytically. The optical Kerr effect is enhanced by the local electromagnetic field of surface plasmon polaritons, slow light, and graphene–Ag composite material structures with a large effective Kerr nonlinear coefficient. Through the dynamic adjustment of the frequency of the disk nanocavity, the group velocity is controlled between c /53.2 and c /15.1 with the pump light intensity increased from 0.41 MW/cm 2 to 2.05 MW/cm 2 . Alternatively, through the dynamic adjustment of the propagation phase of the plasmonic waveguide, the group velocity is controlled between c /2.8 and c /14.8 with the pump light intensity increased from 5.88 MW/cm 2 to 11.76 MW/cm 2 . The phase shift multiplication of the PIT effect is observed. Calculation results indicate that the entire structure is ultracompact and has a footprint of less than 0.8 μm 2 . An ultrafast responsive time in the order of 1 ps is reached due to the ultrafast carrier relaxation dynamics of graphene. All findings are comprehensively analyzed through finite-difference time-domain simulations and with a coupling-mode equation system. The results can serve as a reference for the design and fabrication of nanoscale integration photonic devices with low power consumption and ultrafast nonlinear responses.

We theoretically and numerically investigate a low-power, ultrafast, and dynamic all-optical tunable plasmon induced transparency (PIT) in two stub resonators side-coupled with a metal-dielectric-metal (MDM) plasmonic waveguide system. The optical Kerr effect is enhanced by the local electromagnetic field of surface plasmon polaritons (SPPs) and the plasmonic waveguide based on graphene-Ag composite material structures with large effective Kerr nonlinear coefficient. An ultrafast response time of the order of 1 ps is reached because of ultrafast carrier relaxation dynamics of graphene. With dynamically tuning the propagation phase of the plasmonic waveguide, pi-phase shift of the transmission spectrum in the PIT system is achieved under excitation of a pump light with an intensity as low as 5.8 MW cm(-2). The group delay is controlled between 0.14 and 0.67 ps. Moreover, the tunable bandwidth of about 42 nm is obtained. For the indirect coupling between two stub cavities or the phase coupling scheme, the phase shift multiplication effect of the PIT effect is found. All observed schemes are analyzed rigorously through finite-difference time-domain simulations and coupled-mode formalism. This work not only paves the way towards the realization of on-chip integrated nanophotonic devices but also opens the possibility of the construction of ultrahigh-speed information processing chips based on plasmonic circuits.

We theoretically and numerically investigate all-optical Mach-Zehnder interferometer switching based on the phase-shift multiplication effect of an all-optical analog on the electromagnetically induced transparency effect. The free-carrier plasma dispersion effect modulation method is applied to improve the tuning rate with a response time of picoseconds. All observed schemes are analyzed rigorously through finite-difference time-domain simulations and coupled-mode formalism. Compared with no phase-shift multiplication effect, the average pump power of all-optical switching required to yield the pi-phase shift difference decreases by 55.1%, and the size of the modulation region is reduced by 50.1% when the average pump power reaches 60.8 mW. This work provides a new direction for low-power consumption and miniaturization of microstructure integration light-controlled switching devices in optical communication and quantum information processing. (C) 2016 Society of Photo-Optical Instrumentation Engineers (SPIE)