MICROELECTROMECHANICAL SYSTEMS ENABLED TUNABLE TERAHERTZ METAMATERIALS

Ph.DDOCTOR OF PHILOSOPH

Electrically Programmable Terahertz Diatomic Metamolecules for Chiral Optical Control

Optical chirality is central to many industrial photonic technologies including enantiomer identification, ellipsometry-based tomography, and spin multiplexing in optical communications. However, a substantial chiral response requires a three-dimensional constituent, thereby making the morphology highly complex to realize structural reconfiguration. Moreover, an active reconfiguration demands intense dosage of external stimuli that pose a major limitation for on-chip integration. Here, we report a low bias, electrically programmable synthetic chiral paradigm with a remarkable reconfiguration among levorotatory, dextrorotatory, achiral, and racemic conformations. The switchable optical activity induced by the chiral conformations enables a transmission-type duplex spatial light modulator for terahertz single pixel imaging. The prototype delivers a new strategy towards reconfigurable stereoselective photonic applications and opens up avenues for on-chip programmable chiral devices with tremendous applications in biology, medicine, chemistry, and photonics

Electrically programmable terahertz diatomic metamolecules for chiral optical control

Optical chirality is central to many industrial photonic technologies including enantiomer identification, ellipsometry-based tomography, and spin multiplexing in optical communications. However, a substantial chiral response requires a threedimensional constituent, thereby making the morphology highly complex to realize structural reconfiguration. Moreover, an active reconfiguration demands intense dosage of external stimuli that pose a major limitation for on-chip integration. Here, we report a low bias, electrically programmable synthetic chiral paradigm with a remarkable reconfiguration among levorotatory, dextrorotatory, achiral, and racemic conformations. The switchable optical activity induced by the chiral conformations enables a transmission-type duplex spatial light modulator for terahertz single pixel imaging. The prototype delivers a new strategy towards reconfigurable stereoselective photonic applications and opens up avenues for on-chip programmable chiral devices with tremendous applications in biology, medicine, chemistry, and photonics.NRF (Natl Research Foundation, S’pore)MOE (Min. of Education, S’pore)Published versio

Active control of resonant cloaking in a terahertz MEMS metamaterial

Metamaterials exhibiting exotic optical properties have played a significant role over the years in guiding the concept of invisibility cloaking from the realm of being fiction to reality. However, due to the difficulties in fabricating the 3D cloaking devices and lack of exotic plasmonic materials at terahertz (THz) frequencies, the experimental realization of cloaking phenomenon in the THz spectrum is challenging. In this work, a new mechanism for invisibility cloaking based on the resonant scattering cancellation technique in a 2D nonconcentric composite metamaterial device, consisting of a split ring resonator (SRR) and a microelectromechanical system (MEMS) reconfigurable closed ring resonator (CRR) at THz frequencies is reported. A strong magnetic interaction between the SRR and CRR eliminates the scattering effects from the SRR at its fundamental eigen mode frequency, thereby making it invisible to the incident THz wave. Further, by voltage actuation of MEMS‐reconfigurable CRR, an active switching between the visible and cloaked states of SRR structure is demonstrated. The proposed technique provides a simple design and technique for realizing invisibility cloaks by utilizing the resonant near‐field interactions in the subwavelength structures across microwave to optical frequencies, thereby circumventing the need for materials with complex geometry and exotic properties.NRF (Natl Research Foundation, S’pore)MOE (Min. of Education, S’pore)Accepted versio

Tantalum-nitride antifuse electromechanical OTP for embedded memory applications

10.1109/LED.2013.2262918IEEE Electron Device Letters348987-989EDLE

Complementary metamaterial infrared absorber

10.1109/OMN.2013.6659100International Conference on Optical MEMS and Nanophotonics143-14

High Temperature Coupling of IR Inactive CC Mode in Complementary Metal Oxide Semiconductor Metamaterial Structure

10.1002/adom.201600778Advanced Optical Materials531600778-160077