Honors & Awards

  • Sigma Xi Best Ph.D. Thesis Award, Georgia Institute of Technology (March 2021)
  • SPIE Optics and Photonics Education Scholarship, Society of Photo-optical Instrumentation Engineers (SPIE) (May 2020)
  • The ECE Graduate Research Assistant Excellence Award, Georgia Institute of Technology (March 2020)
  • The Best Poster Award in IEEE Photonics Conference, Institute of Electrical and Electronics Engineers (IEEE) (October 2017)

Boards, Advisory Committees, Professional Organizations

  • Invited Guest Editor, Journal: Electronics (Special Issue) (2021 - Present)
  • Invited Guest Editor, Journal: Symmetry (Special Issue) (2021 - Present)

Professional Education

  • Ph.D., Georgia Institute of Technology, Electrical & Computer Engineering (2020)
  • M.Sc., Georgia Institute of Technology, Materials Science & Engineering (2016)
  • M.Sc., University of Tehran, Solid State Physics & Electronics (2014)

Stanford Advisors

All Publications

  • Electrically driven reprogrammable phase-change metasurface reaching 80% efficiency. Nature communications Abdollahramezani, S., Hemmatyar, O., Taghinejad, M., Taghinejad, H., Krasnok, A., Eftekhar, A. A., Teichrib, C., Deshmukh, S., El-Sayed, M. A., Pop, E., Wuttig, M., Alo, A., Cai, W., Adibi, A. 2022; 13 (1): 1696


    Phase-change materials (PCMs) offer a compelling platform for active metaoptics, owing to their large index contrast and fast yet stable phase transition attributes. Despite recent advances in phase-change metasurfaces, a fully integrable solution that combines pronounced tuning measures, i.e., efficiency, dynamic range, speed, and power consumption, is still elusive. Here, we demonstrate an in situ electrically driven tunable metasurface by harnessing the full potential of a PCM alloy, Ge2Sb2Te5 (GST), to realize non-volatile, reversible, multilevel, fast, and remarkable optical modulation in the near-infrared spectral range. Such a reprogrammable platform presents a record eleven-fold change in the reflectance (absolute reflectance contrast reaching 80%), unprecedented quasi-continuous spectral tuning over 250nm, and switching speed that can potentially reach a few kHz. Our scalable heterostructure architecture capitalizes on the integration of a robust resistive microheater decoupled from an optically smart metasurface enabling good modal overlap with an ultrathin layer of the largest index contrast PCM to sustain high scattering efficiency even after several reversible phase transitions. We further experimentally demonstrate an electrically reconfigurable phase-change gradient metasurface capable of steering an incident light beam into different diffraction orders. This work represents a critical advance towards the development of fully integrable dynamic metasurfaces and their potential for beamforming applications.

    View details for DOI 10.1038/s41467-022-29374-6

    View details for PubMedID 35354813

  • Dynamic Hybrid Metasurfaces. Nano letters Abdollahramezani, S. n., Hemmatyar, O. n., Taghinejad, M. n., Taghinejad, H. n., Kiarashinejad, Y. n., Zandehshahvar, M. n., Fan, T. n., Deshmukh, S. n., Eftekhar, A. A., Cai, W. n., Pop, E. n., El-Sayed, M. A., Adibi, A. n. 2021


    Efficient hybrid plasmonic-photonic metasurfaces that simultaneously take advantage of the potential of both pure metallic and all-dielectric nanoantennas are identified as an emerging technology in flat optics. Nevertheless, postfabrication tunable hybrid metasurfaces are still elusive. Here, we present a reconfigurable hybrid metasurface platform by incorporating the phase-change material Ge2Sb2Te5 (GST) into metal-dielectric meta-atoms for active and nonvolatile tuning of properties of light. We systematically design a reduced-dimension meta-atom, which selectively controls the hybrid plasmonic-photonic resonances of the metasurface via the dynamic change of optical constants of GST without compromising the scattering efficiency. As a proof-of-concept, we experimentally demonstrate two tunable metasurfaces that control the amplitude (with relative modulation depth as high as ≈80%) or phase (with tunability >230°) of incident light promising for high-contrast optical switching and efficient anomalous to specular beam deflection, respectively. Our findings further substantiate dynamic hybrid metasurfaces as compelling candidates for next-generation reprogrammable meta-optics.

    View details for DOI 10.1021/acs.nanolett.0c03625

    View details for PubMedID 33481600

  • Synthetic Engineering of Morphology and Electronic Band Gap in Lateral Heterostructures of Monolayer Transition Metal Dichalcogenides ACS NANO Taghinejad, H., Taghinejad, M., Eftekhar, A. A., Li, Z., West, M. P., Javani, M. H., Abdollahramezani, S., Zhang, X., Tian, M., Johnson-Averette, T., Ajayan, P. M., Vogel, E. M., Shi, S., Cai, W., Adibi, A. 2020; 14 (5): 6323–30


    Heterostructures of two-dimensional transition metal dichalcogenides (TMDs) can offer a plethora of opportunities in condensed matter physics, materials science, and device engineering. However, despite state-of-the-art demonstrations, most current methods lack enough degrees of freedom for the synthesis of heterostructures with engineerable properties. Here, we demonstrate that combining a postgrowth chalcogen-swapping procedure with the standard lithography enables the realization of lateral TMD heterostructures with controllable dimensions and spatial profiles in predefined locations on a substrate. Indeed, our protocol receives a monolithic TMD monolayer (e.g., MoSe2) as the input and delivers lateral heterostructures (e.g., MoSe2-MoS2) with fully engineerable morphologies. In addition, through establishing MoS2xSe2(1-x)-MoS2ySe2(1-y) lateral junctions, our synthesis protocol offers an extra degree of freedom for engineering the band gap energies up to ∼320 meV on each side of the heterostructure junction via changing x and y independently. Our electron microscopy analysis reveals that such continuous tuning stems from the random intermixing of sulfur and selenium atoms following the chalcogen swapping. We believe that, by adding an engineering flavor to the synthesis of TMD heterostructures, our study lowers the barrier for the integration of two-dimensional materials into practical optoelectronic platforms.

    View details for DOI 10.1021/acsnano.0c02885

    View details for Web of Science ID 000537682300114

    View details for PubMedID 32364693

  • Photocarrier-Induced Active Control of Second-Order Optical Nonlinearity in Monolayer MoS2 SMALL Taghinejad, M., Xu, Z., Wang, H., Taghinejad, H., Lee, K., Rodrigues, S. P., Adibi, A., Qian, X., Lian, T., Cai, W. 2020; 16 (5): e1906347


    Atomically thin transition metal dichalcogenides (TMDs) in their excited states can serve as exceptionally small building blocks for active optical platforms. In this scheme, optical excitation provides a practical approach to control light-TMD interactions via the photocarrier generation, in an ultrafast manner. Here, it is demonstrated that via a controlled generation of photocarriers the second-harmonic generation (SHG) from a monolayer MoS2 crystal can be substantially modulated up to ≈55% within a timeframe of ≈250 fs, a set of performance characteristics that showcases the promise of low-dimensional materials for all-optical nonlinear data processing. The combined experimental and theoretical study suggests that the large SHG modulation stems from the correlation between the second-order dielectric susceptibility χ(2) and the density of photoexcited carriers in MoS2 . Indeed, the depopulation of the conduction band electrons, at the vicinity of the high-symmetry K/K' points of MoS2 , suppresses the contribution of interband electronic transitions in the effective χ(2) of the monolayer crystal, enabling the all-optical modulation of the SHG signal. The strong dependence of the second-order optical response on the density of photocarriers reveals the promise of time-resolved nonlinear characterization as an alternative route to monitoring carrier dynamics in excited states of TMDs.

    View details for DOI 10.1002/smll.201906347

    View details for Web of Science ID 000506918800001

    View details for PubMedID 31943782

  • Transient Second-Order Nonlinear Media: Breaking the Spatial Symmetry in the Time Domain via Hot-Electron Transfer PHYSICAL REVIEW LETTERS Taghinejad, M., Xu, Z., Lee, K., Lian, T., Cai, W. 2020; 124 (1): 013901


    Second-order optical effects are essential to the active control of light and the generation of new spectral components. The inversion symmetry, however, prevents achieving a bulk χ^{(2)} response, limiting the portfolio of the second-order nonlinear materials. Here, we demonstrate subpicosecond conversion of a statically passive dielectric to a transient second-order nonlinear medium upon the ultrafast transfer of hot electrons. Induced by an optical switching signal, the amorphous dielectric with vanishing intrinsic χ^{(2)} develops dynamically tunable second-order nonlinear responses. By taking the second-harmonic generation as an example, we show that breaking the inversion symmetry through hot-electron dynamics can be leveraged to address the critical need for all-optical control of second-order nonlinearities in nanophotonics. Our approach can be generically adopted in a variety of material and device platforms, offering a new class of complex nonlinear media with promising potentials for all-optical information processing.

    View details for DOI 10.1103/PhysRevLett.124.013901

    View details for Web of Science ID 000505495300012

    View details for PubMedID 31976680

  • Electrically Biased Silicon Metasurfaces with Magnetic Mie Resonance for Tunable Harmonic Generation of Light ACS PHOTONICS Lee, K., Taghinejad, M., Yan, J., Kim, A. S., Raju, L., Brown, D. K., Cai, W. 2019; 6 (11): 2663–70
  • All-Optical Control of Light in Micro- and Nanophotonics ACS PHOTONICS Taghinejad, M., Cai, W. 2019; 6 (5): 1082–93
  • Metasurfaces for Near-Eye Augmented Reality ACS PHOTONICS Lan, S., Zhang, X., Taghinejad, M., Rodrigues, S., Lee, K., Liu, Z., Cai, W. 2019; 6 (4): 864–70
  • Sharp and Tunable Crystal/Fano-Type Resonances Enabled by Out-of-Plane Dipolar Coupling in Plasmonic Nanopatch Arrays ANNALEN DER PHYSIK Taghinejad, M., Taghinejad, H., Malak, S. T., Moradinejad, H., Woods, E. V., Xu, Z., Liu, Y., Eftekhar, A. A., Lian, T., Tsukruk, V. V., Adibi, A. 2018; 530 (10)
  • Ultrafast Control of Phase and Polarization of Light Expedited by Hot-Electron Transfer NANO LETTERS Taghinejad, M., Taghinejad, H., Xu, Z., Lee, K., Rodrigues, S. P., Yan, J., Adibi, A., Lian, T., Cai, W. 2018; 18 (9): 5544–51


    All-optical modulation is an entangled part of ultrafast nonlinear optics with promising impacts on tunable optical devices in the future. Current advancements in all-optical control predominantly offer modulation by means of altering light intensity, while the ultrafast manipulation of other attributes of light have yet to be further explored. Here, we demonstrate the active modulation of the phase, polarization, and amplitude of light through the nonlinear modification of the optical response of a plasmonic crystal that supports subradiant, high Q, and polarization-selective resonance modes. The designed mode is exclusively accessible via TM-polarized light, which enables significant phase modulation and polarization conversion within the visible spectrum. To tailor the device performance in the time domain, we exploit the ultrafast transport dynamics of hot electrons at the interface of plasmonic metals and charge acceptor materials to facilitate an ultrafast switching speed. In addition, the operating wavelength of the proposed device can be tuned through the control of the in-plane momentum of light. Our work reveals the viability of dynamic phase and polarization control in plasmonic systems for all-optical switching and data processing.

    View details for DOI 10.1021/acs.nanolett.8b01946

    View details for Web of Science ID 000444793500028

    View details for PubMedID 30071164

  • Strain relaxation via formation of cracks in compositionally modulated two-dimensional semiconductor alloys NPJ 2D MATERIALS AND APPLICATIONS Taghinejad, H., Eftekhar, A. A., Campbell, P. M., Beatty, B., Taghinejad, M., Zhou, Y., Perini, C. J., Moradinejad, H., Henderson, W. E., Woods, E. V., Zhang, X., Ajayan, P., Reed, E. J., Vogel, E. M., Adibi, A. 2018; 2: 1–8
  • Hot-Electron-Assisted Femtosecond All-Optical Modulation in Plasmonics ADVANCED MATERIALS Taghinejad, M., Taghinejad, H., Xu, Z., Liu, Y., Rodrigues, S. P., Lee, K., Lian, T., Adibi, A., Cai, W. 2018; 30 (9)


    The optical Kerr nonlinearity of plasmonic metals provides enticing prospects for developing reconfigurable and ultracompact all-optical modulators. In nanostructured metals, the coherent coupling of light energy to plasmon resonances creates a nonequilibrium electron distribution at an elevated electron temperature that gives rise to significant Kerr optical nonlinearities. Although enhanced nonlinear responses of metals facilitate the realization of efficient modulation devices, the intrinsically slow relaxation dynamics of the photoexcited carriers, primarily governed by electron-phonon interactions, impedes ultrafast all-optical modulation. Here, femtosecond (≈190 fs) all-optical modulation in plasmonic systems via the activation of relaxation pathways for hot electrons at the interface of metals and electron acceptor materials, following an on-resonance excitation of subradiant lattice plasmon modes, is demonstrated. Both the relaxation kinetics and the optical nonlinearity can be actively tuned by leveraging the spectral response of the plasmonic design in the linear regime. The findings offer an opportunity to exploit hot-electron-induced nonlinearities for design of self-contained, ultrafast, and low-power all-optical modulators based on plasmonic platforms.

    View details for DOI 10.1002/adma.201704915

    View details for Web of Science ID 000426491600007

    View details for PubMedID 29333735

  • Lattice Plasmon Induced Large Enhancement of Excitonic Emission in Monolayer Metal Dichalcogenides PLASMONICS Taghinejad, H., Shams-Mousavi, S., Gong, Y., Taghinejad, M., Eftekhar, A. A., Ajayan, P., Adibi, A. 2017; 12 (6): 1975-1981
  • Preserving Spin States upon Reflection: Linear and Nonlinear Responses of a Chiral Meta-Mirror NANO LETTERS Kang, L., Rodrigues, S. P., Taghinejad, M., Lan, S., Lee, K., Liu, Y., Werner, D. H., Urbas, A., Cai, W. 2017; 17 (11): 7102–9


    Conventional metallic mirrors flip the spin of a circularly polarized wave upon normal incidence by inverting the direction of the propagation vector. Altering or maintaining the spin state of light waves carrying data is a critical need to be met at the brink of photonic information processing. In this work, we report a chiral metamaterial mirror that strongly absorbs a circularly polarized wave of one spin state and reflects that of the opposite spin in a manner conserving the circular polarization. A circular dichroic response in reflection as large as ∼0.5 is experimentally observed in a near-infrared wavelength band. By imaging a fabricated pattern composed of the enantiomeric unit cells, we directly visualize the two key features of our engineered meta-mirrors, namely the chiral-selective absorption and the polarization preservation upon reflection. Beyond the linear regime, the chiral resonances enhance light-matter interaction under circularly polarized excitation, greatly boosting the ability of the metamaterial to perform chiral-selective signal generation and optical imaging in the nonlinear regime. Chiral meta-mirrors, exhibiting giant chiroptical responses and spin-selective near-field enhancement, hold great promise for applications in polarization sensitive electro-optical information processing and biosensing.

    View details for DOI 10.1021/acs.nanolett.7b03882

    View details for Web of Science ID 000415029000089

    View details for PubMedID 29072915

  • Dark plasmonic modes in diatomic gratings for plasmoelectronics LASER & PHOTONICS REVIEWS Lan, S., Rodrigues, S. P., Taghinejad, M., Cai, W. 2017; 11 (2)
  • Resonant Light-Induced Heating in Hybrid Cavity-Coupled 2D Transition-Metal Dichalcogenides ACS PHOTONICS Taghinejad, H., Taghinejad, M., Tarasov, A., Tsai, M., Hosseinnia, A. H., Moradinejad, H., Campbell, P. M., Eftekhar, A. A., Vogel, E. M., Adibi, A. 2016; 3 (4): 700–707
  • The conformal silicon deposition on carbon nanotubes as enabled by hydrogenated carbon coatings for synthesis of carbon/silicon core/shell heterostructure photodiodes CARBON Taghinejad, H., Taghinejad, M., Abdolahad, M., Rajabali, S., Rostamian, A., Mohajerzadeh, S., Hosseinian, E. 2015; 87: 299–308
  • Integration of Ni2Si/Si Nanograss Heterojunction on n-MOSFET to Realize High-Sensitivity Phototransistors IEEE TRANSACTIONS ON ELECTRON DEVICES Taghinejad, M., Taghinejad, H., Ganji, M., Rostamian, A., Mohajerzadeh, S., Abdolahad, M., Kolahdouz, M. 2014; 61 (9): 3239–44
  • Cell-imprinted substrates act as an artificial niche for skin regeneration. ACS applied materials & interfaces Mashinchian, O., Bonakdar, S., Taghinejad, H., Satarifard, V., Heidari, M., Majidi, M., Sharifi, S., Peirovi, A., Saffar, S., Taghinejad, M., Abdolahad, M., Mohajerzadeh, S., Shokrgozar, M. A., Rezayat, S. M., Ejtehadi, M. R., Dalby, M. J., Mahmoudi, M. 2014; 6 (15): 13280-13292


    Bioinspired materials can mimic the stem cell environment and modulate stem cell differentiation and proliferation. In this study, biomimetic micro/nanoenvironments were fabricated by cell-imprinted substrates based on mature human keratinocyte morphological templates. The data obtained from atomic force microscopy and field emission scanning electron microscopy revealed that the keratinocyte-cell-imprinted poly(dimethylsiloxane) casting procedure could imitate the surface morphology of the plasma membrane, ranging from the nanoscale to the macroscale, which may provide the required topographical cell fingerprints to induce differentiation. Gene expression levels of the genes analyzed (involucrin, collagen type I, and keratin 10) together with protein expression data showed that human adipose-derived stem cells (ADSCs) seeded on these cell-imprinted substrates were driven to adopt the specific shape and characteristics of keratinocytes. The observed morphology of the ADSCs grown on the keratinocyte casts was noticeably different from that of stem cells cultivated on the stem-cell-imprinted substrates. Since the shape and geometry of the nucleus could potentially alter the gene expression, we used molecular dynamics to probe the effect of the confining geometry on the chain arrangement of simulated chromatin fibers in the nuclei. The results obtained suggested that induction of mature cell shapes onto stem cells can influence nucleus deformation of the stem cells followed by regulation of target genes. This might pave the way for a reliable, efficient, and cheap approach of controlling stem cell differentiation toward skin cells for wound healing applications.

    View details for DOI 10.1021/am503045b

    View details for PubMedID 24967724

  • Realization of highly crystallographic three-dimensional nanosheets by a stress-induced oriented-diffusion method APPLIED PHYSICS LETTERS Gharooni, M., Hosseini, M., Mohajerzadeh, S., Taghinejad, M., Taghinejad, H., Abdi, Y. 2014; 105 (4)

    View details for DOI 10.1063/1.4892091

    View details for Web of Science ID 000341152600074

  • Cell membrane electrical charge investigations by silicon nanowires incorporated field effect transistor (SiNWFET) suitable in cancer research RSC ADVANCES Abdolahad, M., Taghinejad, H., Saeidi, A., Taghinejad, M., Janmaleki, M., Mohajerzadeh, S. 2014; 4 (15): 7425-7431

    View details for DOI 10.1039/c3ra46272b

    View details for Web of Science ID 000330241000009

  • A Nickel-Gold Bilayer Catalyst Engineering Technique for Self-Assembled Growth of Highly Ordered Silicon Nanotubes (SiNT) NANO LETTERS Taghinejad, M., Taghinejad, H., Abdolahad, M., Mohajerzadeh, S. 2013; 13 (3): 889–97


    We report the growth of vertically aligned high-crystallinity silicon nanotube (SiNT) arrays on silicon substrate by means of a Ni-Au bilayer catalyst engineering technique. Nanotubes were synthesized through solid-liquid-solid method as well as vapor-liquid-solid. A precise evaluation utilizing atomic force microscopy and lateral force microscopy describes that the gold profile in Ni regions leads to the construction of multiwall SiNTs. The agreement of the structural geometry and stiffness of the obtained SiNTs with previous theoretical predictions suggest sp(3) hybridization as the mechanism of tube formation. Apart from scanning electron and transmission electron microscopy techniques, photoluminescence spectroscopy (PL) has been conducted to investigate the formation of nanostructures. PL spectroscopy confirms the evolution of ultrafine walls of the silicon nanotubes, responsible for the observed photoemission properties.

    View details for DOI 10.1021/nl303558f

    View details for Web of Science ID 000316243800006

    View details for PubMedID 23394626

  • Fabrication and modeling of high sensitivity humidity sensors based on doped silicon nanowires SENSORS AND ACTUATORS B-CHEMICAL Taghinejad, H., Taghinejad, M., Abdolahad, M., Saeidi, A., Mohajerzadeh, S. 2013; 176: 413–19
  • Evaluation of the shear force of single cancer cells by vertically aligned carbon nanotubes suitable for metastasis diagnosis INTEGRATIVE BIOLOGY Abdolahad, M., Mohajerzadeh, S., Janmaleki, M., Taghinejad, H., Taghinejad, M. 2013; 5 (3): 535-542


    Vertically aligned carbon nanotube (VACNT) arrays have been demonstrated as probes for rapid quantifying of cancer cell deformability with high resolution. Through entrapment of various cancer cells on CNT arrays, the deflections of the nanotubes during cell deformation were used to derive the lateral cell shear force using a large deflection mode method. It is observed that VACNT beams act as sensitive and flexible agents, which transfer the shear force of cells trapped on them by an observable deflection. The metastatic cancer cells have significant deformable structures leading to a further cell traction force (CTF) than primary cancerous one on CNT arrays. The elasticity of different cells could be compared by their CTF measurement on CNT arrays. This study presents a nanotube-based methodology for quantifying the single cell mechanical behavior, which could be useful for understanding the metastatic behavior of cells.

    View details for DOI 10.1039/c2ib20215h

    View details for Web of Science ID 000315354900008

    View details for PubMedID 23340873

  • Single-cell resolution diagnosis of cancer cells by carbon nanotube electrical spectroscopy NANOSCALE Abdolahad, M., Janmaleki, M., Taghinejad, M., Taghnejad, H., Salehi, F., Mohajerzadeh, S. 2013; 5 (8): 3421-3427


    We report the use of vertically aligned carbon nanotubes (VACNTs) as electrical endoscopes (biosensors) for cancer metastatic diagnosis at single-cell resolution. The device is based on direct signal extraction by means of vertically aligned conductive carbon nanotubes from a live cell membrane, which has been disrupted during carcinogenesis at its primary and progressive stages. The value of this electrical disruption depends on the cancer metastatic grade. In addition, the electrical resonance behavior of the cell, halted during cancer progression, could be monitored as a new cancer diagnostic profile. By taking a second derivative of the cell impedance with respect to applied frequency, we have arrived at a new spectroscopy tool for distinguishing cancerous stages of colon and breast carcinoma cells.

    View details for DOI 10.1039/c3nr33430a

    View details for Web of Science ID 000316959500043

    View details for PubMedID 23474499

  • A vertically aligned carbon nanotube-based impedance sensing biosensor for rapid and high sensitive detection of cancer cells LAB ON A CHIP Abdolahad, M., Taghinejad, M., Taghinejad, H., Janmaleki, M., Mohajerzadeh, S. 2012; 12 (6): 1183-1190


    A novel vertically aligned carbon nanotube based electrical cell impedance sensing biosensor (CNT-ECIS) was demonstrated for the first time as a more rapid, sensitive and specific device for the detection of cancer cells. This biosensor is based on the fast entrapment of cancer cells on vertically aligned carbon nanotube arrays and leads to mechanical and electrical interactions between CNT tips and entrapped cell membranes, changing the impedance of the biosensor. CNT-ECIS was fabricated through a photolithography process on Ni/SiO(2)/Si layers. Carbon nanotube arrays have been grown on 9 nm thick patterned Ni microelectrodes by DC-PECVD. SW48 colon cancer cells were passed over the surface of CNT covered electrodes to be specifically entrapped on elastic nanotube beams. CNT arrays act as both adhesive and conductive agents and impedance changes occurred as fast as 30 s (for whole entrapment and signaling processes). CNT-ECIS detected the cancer cells with the concentration as low as 4000 cells cm(-2) on its surface and a sensitivity of 1.7 × 10(-3)Ω cm(2). Time and cell efficiency factor (TEF and CEF) parameters were defined which describe the sensor's rapidness and resolution, respectively. TEF and CEF of CNT-ECIS were much higher than other cell based electrical biosensors which are compared in this paper.

    View details for DOI 10.1039/c2lc21028b

    View details for Web of Science ID 000300511500023

    View details for PubMedID 22294045