title: Ultra-high dynamic range electro-optic sampling for detecting millimeter and sub-millimeter radiation.
abstract: Time-domain spectroscopy using coherent millimeter and sub-millimeter radiation (also known as terahertz radiation) is rapidly expanding its application, owing greatly to the remarkable advances in generating and detecting such radiation. However, many current techniques for coherent terahertz detection have limited dynamic range, thus making it difficult to perform some basic experiments that need to directly compare strong and weak terahertz signals. Here, we propose and demonstrate a novel technique based on cross-polarized spectral-domain interferometry to achieve ultra-high dynamic range electro-optic sampling measurement of coherent millimeter and sub-millimeter radiation. In our scheme, we exploit the birefringence in a single-mode polarization maintaining fiber in order to measure the phase change induced by the electric field of terahertz radiation in the detection crystal. With our new technique, we have achieved a dynamic range of 7 × 10(6), which is 4 orders of magnitude higher than conventional electro-optic sampling techniques, while maintaining comparable signal-to-noise ratio. The present technique is foreseen to have great impact on experiments such as linear terahertz spectroscopy of optically thick materials (such as aqueous samples) and nonlinear terahertz spectroscopy, where the higher dynamic range is crucial for proper interpretation of experimentally obtained results.
authors.affiliation: INRS-EMT, Advanced Laser Light Source, Université du Québec, 1650 boul. Lionel- Boulet, Varennes J3X 1S2, Québec, Canada.
authors.forename: Akram
authors.initials: A
authors.lastname: Ibrahim
authors.affiliation: INRS-EMT, Advanced Laser Light Source, Université du Québec, 1650 boul. Lionel- Boulet, Varennes J3X 1S2, Québec, Canada.
authors.forename: Denis
authors.initials: D
authors.lastname: Férachou
authors.affiliation: University of Massachusetts Lowell, 1 University Avenue, Lowell, 01854, Massachusetts, USA.
authors.forename: Gargi
authors.initials: G
authors.lastname: Sharma
authors.affiliation: Harvard Medical School, Massachusetts General Hospital, 40 Blossom Street, Boston, 02114, Massachusetts, USA.
authors.forename: Kanwarpal
authors.initials: K
authors.lastname: Singh
authors.affiliation: INRS-EMT, Advanced Laser Light Source, Université du Québec, 1650 boul. Lionel- Boulet, Varennes J3X 1S2, Québec, Canada.
authors.forename: Marie
authors.initials: M
authors.lastname: Kirouac-Turmel
authors.affiliation: INRS-EMT, Advanced Laser Light Source, Université du Québec, 1650 boul. Lionel- Boulet, Varennes J3X 1S2, Québec, Canada.
authors.forename: Tsuneyuki
authors.initials: T
authors.lastname: Ozaki