The invention, titled "ACTIVE TERAHERTZ METAMATERIAL DEVICES," is a patent granted to Los Alamos National Security, LLC, for a novel method and apparatus for modulating terahertz (THz) frequency signals using metamaterial structures. The invention was filed on April 3, 2009, and published on October 22, 2009. The patent describes a metamaterial array fabricated on a semiconducting substrate, where each element in the array consists of multiple loops and gaps. These elements can be resonators with conductive loops and insulated gaps or vice versa, providing transmissive control properties. The metamaterial elements are designed to enhance or deplete electrons near the gaps, achieving an on-to-off transmissivity ratio of about 0.5. The invention includes applications in Quantum Cascade Lasers (QCLs) to enable surface-emitting properties. The device operates at room temperature and offers significant improvements over existing THz modulators, with a modulation efficiency of over ten times greater than current state-of-the-art electrically operated modulators. The invention also discusses the design, fabrication, and experimental characterization of the metamaterial device, including its performance at different gate voltages and polarization configurations.The invention, titled "ACTIVE TERAHERTZ METAMATERIAL DEVICES," is a patent granted to Los Alamos National Security, LLC, for a novel method and apparatus for modulating terahertz (THz) frequency signals using metamaterial structures. The invention was filed on April 3, 2009, and published on October 22, 2009. The patent describes a metamaterial array fabricated on a semiconducting substrate, where each element in the array consists of multiple loops and gaps. These elements can be resonators with conductive loops and insulated gaps or vice versa, providing transmissive control properties. The metamaterial elements are designed to enhance or deplete electrons near the gaps, achieving an on-to-off transmissivity ratio of about 0.5. The invention includes applications in Quantum Cascade Lasers (QCLs) to enable surface-emitting properties. The device operates at room temperature and offers significant improvements over existing THz modulators, with a modulation efficiency of over ten times greater than current state-of-the-art electrically operated modulators. The invention also discusses the design, fabrication, and experimental characterization of the metamaterial device, including its performance at different gate voltages and polarization configurations.