Abstract

Coherent detection and interferometry in the terahertz (THz) regime are key capabilities that enable applications ranging from astronomy to non-destructive testing. Phase-sensitive THz detection is currently achieved using nonlinear crystals or external interferometers and photomixers. However, the former approach requires femtosecond pulsed radiation, and all approaches suffer from a large footprint and sensitive alignment. Here, we demonstrate a graphene-enabled, on-chip, integrated THz detector-interferometer with optical cavity and antenna, exhibiting high sensitivity to the phase of incident THz light. We exploit this by determining the thickness of thin films placed in front of the detector-interferometer, obtaining a strongly sub-wavelength thickness accuracy of ∼5 µm, while we predict that an accuracy of 10 nm is within reach. The detector-interferometer moreover exhibits a record-high external responsivity of 73 mA/W and a noise-equivalent power of 79 pW Hz⁻¹/2. This performance is due to enhanced absorption at the cavity mode around 89 GHz, in agreement with multi-physics simulations.

Abstract

Coherent detection and interferometry in the terahertz (THz) regime are key capabilities that enable applications ranging from astronomy to non-destructive testing. Phase-sensitive THz detection is currently achieved using nonlinear crystals or external interferometers and photomixers. However, the former approach requires femtosecond pulsed radiation, and all approaches suffer from a large footprint and sensitive alignment. Here, we demonstrate a graphene-enabled, on-chip, integrated THz detector-interferometer with optical cavity and antenna, exhibiting high sensitivity to the phase of incident THz light. We exploit this by determining the thickness of thin films placed in front of the detector-interferometer, obtaining a strongly sub-wavelength thickness accuracy of ∼5 µm, while we predict that an accuracy of 10 nm is within reach. The detector-interferometer moreover exhibits a record-high external responsivity of 73 mA/W and a noise-equivalent power of 79 pW Hz⁻¹/2. This performance is due to enhanced absorption at the cavity mode around 89 GHz, in agreement with multi-physics simulations.

Abstract

Coherent detection and interferometry in the terahertz (THz) regime are key capabilities that enable applications ranging from astronomy to non-destructive testing. Phase-sensitive THz detection is currently achieved using nonlinear crystals or external interferometers and photomixers. However, the former approach requires femtosecond pulsed radiation, and all approaches suffer from a large footprint and sensitive alignment. Here, we demonstrate a graphene-enabled, on-chip, integrated THz detector-interferometer with optical cavity and antenna, exhibiting high sensitivity to the phase of incident THz light. We exploit this by determining the thickness of thin films placed in front of the detector-interferometer, obtaining a strongly sub-wavelength thickness accuracy of ∼5 µm, while we predict that an accuracy of 10 nm is within reach. The detector-interferometer moreover exhibits a record-high external responsivity of 73 mA/W and a noise-equivalent power of 79 pW Hz⁻¹/2. This performance is due to enhanced absorption at the cavity mode around 89 GHz, in agreement with multi-physics simulations.

Abstract

Coherent detection and interferometry in the terahertz (THz) regime are key capabilities that enable applications ranging from astronomy to non-destructive testing. Phase-sensitive THz detection is currently achieved using nonlinear crystals or external interferometers and photomixers. However, the former approach requires femtosecond pulsed radiation, and all approaches suffer from a large footprint and sensitive alignment. Here, we demonstrate a graphene-enabled, on-chip, integrated THz detector-interferometer with optical cavity and antenna, exhibiting high sensitivity to the phase of incident THz light. We exploit this by determining the thickness of thin films placed in front of the detector-interferometer, obtaining a strongly sub-wavelength thickness accuracy of ∼5 µm, while we predict that an accuracy of 10 nm is within reach. The detector-interferometer moreover exhibits a record-high external responsivity of 73 mA/W and a noise-equivalent power of 79 pW Hz⁻¹/2. This performance is due to enhanced absorption at the cavity mode around 89 GHz, in agreement with multi-physics simulations.