Daniel V. Pilon

A dual band terahertz metamaterial absorber

We present the design, fabrication and characterization of a dual band metamaterial absorber which experimentally shows two distinct absorption peaks of 0.85 at 1.4 THz and 0.94 at 3.0 THz. The dual band absorber consists of a dual band electric-field-coupled (ELC) resonator and a metallic ground plane, separated by an 8 µm dielectric spacer. Fine tuning of the two absorption resonances is achieved by individually adjusting each ELC resonator geometry.

Comparison of birefringent electric split-ring resonator and meanderline

We have fabricated a quarter-wave plate from a single layer of birefringent electric split-ring resonators (ELC). For comparison, an appropriately scaled double layer meanderline structure was fabricated. At the design frequency of 639 GHz, the ELC structure achieves 99.9% circular polarization while the meanderline achieves 99.6%. The meanderline displays a larger bandwidth of operation, attaining over 99% circular polarization from 615 – 743 GHz, while the ELC achieves 99% from 626 – 660 GHz. However, both are broad enough for use with CW sources making ELCs a more attractive choice due to the ease of fabrication. Both samples are free standing with a total thickness of 70μm for the meanderline structure and a mere 20μm for the ELC highlighting the large degree of birefringence exhibited with metamaterial structures.We compare a single layer metamaterial quarter-wave plate with a meanderline polarizer. They achieve 99.9% and 99.6% circular polarization at 639 GHz, respectively. These results highlight the large degree of birefringence exhibited by metamaterial structures.

Comparison of birefringent electric split-ring resonator and meanderline structures as quarter-wave plates at terahertz frequencies.

We have fabricated a quarter-wave plate from a single layer of birefringent electric split-ring resonators (ELC). For comparison, an appropriately scaled double layer meanderline structure was fabricated. At the design frequency of 639 GHz, the ELC structure achieves 99.9% circular polarization while the meanderline achieves 99.6%. The meanderline displays a larger bandwidth of operation, attaining over 99% circular polarization from 615 – 743 GHz, while the ELC achieves 99% from 626 – 660 GHz. However, both are broad enough for use with CW sources making ELCs a more attractive choice due to the ease of fabrication. Both samples are free standing with a total thickness of 70μm for the meanderline structure and a mere 20μm for the ELC highlighting the large degree of birefringence exhibited with metamaterial structures.We compare a single layer metamaterial quarter-wave plate with a meanderline polarizer. They achieve 99.9% and 99.6% circular polarization at 639 GHz, respectively. These results highlight the large degree of birefringence exhibited by metamaterial structures.

Flexible and reconfigurable terahertz metamaterials

Metamaterial and plasmonic composites have led to the realization that new possibilities abound for creating materials displaying functional electromagnetic properties not realized by nature. Recently, we have extended these ideas by combining metamaterial elements - specifically, split ring resonators - with MEMS technology. This has enabled the creation of non-planar flexible composites and micromechanically active structures where the orientation of the electromagnetically resonant elements can be precisely controlled with respect to the incident field. Such adaptive structures are the starting point for the development of a host of new functional electromagnetic devices which take advantage of designed and tunable anisotropy.

Comparison of birefringent electricsplit-ring resonator and meanderlinestructures as quarter-wave plates atterahertz frequencies

We have fabricated a quarter-wave plate from a single layer of birefringent electric split-ring resonators (ELC). For comparison, an appropriately scaled double layer meanderline structure was fabricated. At the design frequency of 639 GHz, the ELC structure achieves 99.9% circular polarization while the meanderline achieves 99.6%. The meanderline displays a larger bandwidth of operation, attaining over 99% circular polarization from 615 – 743 GHz, while the ELC achieves 99% from 626 – 660 GHz. However, both are broad enough for use with CW sources making ELCs a more attractive choice due to the ease of fabrication. Both samples are free standing with a total thickness of 70μm for the meanderline structure and a mere 20μm for the ELC highlighting the large degree of birefringence exhibited with metamaterial structures.We compare a single layer metamaterial quarter-wave plate with a meanderline polarizer. They achieve 99.9% and 99.6% circular polarization at 639 GHz, respectively. These results highlight the large degree of birefringence exhibited by metamaterial structures.