Dr Maryam Khodadadi

In this paper, a controllable hybrid plasmonic integrated circuit (CHPIC) composed of hybrid plasmonic waveguide (HPW)-based rhombic nano-antenna, polarization beam splitter, coupler, filter, and sensor has been designed and investigated for the first time. In order to control the power into a corresponding input port, a graphene-based 1 × 3 power splitter with switchable output has been exploited. The functionality of each device has been studied comprehensively based on the finite element method and the advantages over state-of-the-art have been compared. Moreover, the effect of connection of CHPIC to the photonic and plasmonic waveguides has been studied to exhibit the capability of variety excitation methods of the CHPIC. Furthermore, the performance of the proposed CHPIC connected to inter/intra wireless transmission links has been investigated. The wireless transmission link consists of two HPW-based nano-antennas as transmitter and receiver with the maximum gain and directivity of 10 dB and 10.2 dBi, respectively, at 193.5 THz. The suggested CHPIC can be used for applications such as optical wireless communication and inter/intra-chip optical interconnects.

In this paper, for the first time, the idea of a dielectric director has been utilized to improve the directivity and gain of the proposed hybrid plasmonic rhombic nano-antenna (HPRNA). The proposed HPRNA can support a horizontal radiation pattern to flourish the concept of wireless transmission link. The horizontal radiation pattern has a 3 dB beamwidth of 43.5°, side lobe level of −11.9 dB, and a directivity and gain of 10.5 dBi and 10.3 dB, respectively, at the operating frequency of 193.5 THz. Moreover, the effects of geometric parameters to verify the functionality of the proposed nano-antenna have been investigated. Finally, the idea of an on-chip wireless transmission link based on transmitting and receiving HPRNAs has been developed and studied theoretically and numerically. The fabrication of the proposed nano-antenna can be done by the typical e-beam lithography (EBL) technique, which is easier than the complicated X-ray method because of its suitable aspect ratio.

In this paper, a smart multi-user wireless link based on a graphene quantum well vertical hybrid plasmonic waveguide-fed nano-antenna is proposed. The theoretical method and finite element method (FEM) are used to verify that the vertical hybrid plasmonic waveguide (VHPW) supports both even and odd fundamental modes. Utilizing multi-mode graphene quantum well VHPW leads to the design of a selective mode nano‑antenna with intermediate broadside and end-fire radiation patterns with high directivities of 9.38 dBi and 11.8 dBi at 193.5 THz, respectively, obtained by the finite-difference time-domain method. Also, to verify the accuracy of nano‑antenna results, the FEM approach is used. The nano-antenna performance as a wireless inter/intra-chip link is investigated, which confirms the even mode plays a key role to create a multiple-access wireless system. Based on the amazing features of graphene as an epsilon-near-zero and absorptive/transparent material, the accessibility of receivers is easily controlled. The effect of a single row array structure and its application as beam steering is studied. Finally, to estimate the performance of quantum well nano-antenna as a real device, which is compatible with electron‑beam lithography and lift-off fabrication techniques, the effect of metal layer roughness and 5% tolerance for geometrical parameters are investigated.

The characteristics of a super-mode waveguide-fed nano-antenna composed of a complementary triangular hybrid plasmonic radiation part have been investigated by two methods of finite element and finite-difference time-domain. Also, a symmetric hybrid plasmonic waveguide (SHPW) has been studied theoretically and numerically to analyze short- and long-range fundamental TM super-modes (TMSR and TMLR) that excite the nano-antenna. The obtained propagation length and figure of merit at 193.5 THz are 150.6 µm (1.27 µm) and 691.77 (16.94) for TMLR (TMSR) super-mode, respectively, which confirm the inevitable loss-confinement trade-off of SHPW. These super-modes cause the nano-antenna to have horizontal and bidirectional radiation patterns due to the existence of the in‑phase and out-of phase super-modes. The obtained directivities and efficiencies are 9.34 dBi (7.01 dBi) and 96.82% (9.66%) for TMLR (TMSR) super-mode, respectively, at 193.5 THz. Moreover, the horizontal and bidirectional radiation patterns are appropriate for on-chip wireless links with the quality factor of 69.18 and target tracking systems, respectively. The performance of a single row array of nano-antenna on improving the directivity and efficiency has been studied. The proposed SHPW-fed nano-antenna is quite tolerant to practical fabrication errors and compatible with lift-off and electron beam lithography fabrication processes.

In this paper, the idea of square fractal geometry has been utilized to introduce a tunable wideband graphene-based perfect plasmonic absorber in the near-infrared region. It consists of a MgF2 layer and an array of gold squares fractal loaded on a graphene layer. In the designed absorber a single layer of graphene has been used instead of multilayered graphene structures. The structure is polarization-insensitive under normal incidence due to the geometric symmetry. The absorption and bandwidth of the structure are almost insensitive to the incident angle up to 15° and 45° for TE and TM polarizations, respectively. Moreover, by choosing appropriate structural parameters, the resonance wavelength of the desired plasmonic absorber can be controlled. The absorption of the introduced structure can be tuned by changing the chemical potential of the graphene. Therefore, the proposed fractal absorber can act as switch and inverter at λ=1995 nm. Furthermore, the equivalent circuit model of the absorber has been derived to confirm the validity of the simulation results. The superiorities of our fractal absorber are wide full-width at half‑maximum of 406 nm, multi-applicant, perfect absorption and fabrication feasibility due to the simple structure with the maximum absorption tolerance error of 5.12%.