High-Sensitivity and Broadband, Real-Time Terahertz Camera Incorporating a Micro-Bolometer Array With Resonant Cavity Structure

Terahertz (THz) cameras comprising an uncooled micro-bolometer array have been developed for simple THz imaging, and the improvement of their sensitivity is one of the important issues. We fabricated a new micro-bolometer array with a resonant cavity structure for a real-time THz camera, alongside a new method for evaluating the sensitivity across a wide range of the THz frequency region. The frequency dependence of the sensitivity of the THz camera is measured in the 0.5-2.0-THz frequency range taking the polarization dependence into account. It was found that the resonant cavity structure effectively increased the sensitivity of the THz camera, and, actually, the improvement by one order of magnitude was achieved in the frequency range below 1 THz. The THz camera with much enhanced sensitivity will expand the frontiers of real-time THz imaging such as molecular imaging and nondestructive inspection.

[1]  Alvydas Lisauskas,et al.  A 0.65 THz Focal-Plane Array in a Quarter-Micron CMOS Process Technology , 2009, IEEE Journal of Solid-State Circuits.

[2]  Linda Marchese,et al.  Case study of concealed weapons detection at stand-off distances using a compact, large field-of-view THz camera , 2014, Defense + Security Symposium.

[3]  Naoki Oda,et al.  Microbolometer terahertz focal plane array and camera with improved sensitivity at 0.5–0.6 THz , 2014, 2014 39th International Conference on Infrared, Millimeter, and Terahertz waves (IRMMW-THz).

[4]  Mikko Leivo,et al.  Passive terahertz camera for standoff security screening. , 2010, Applied optics.

[5]  M. Koch,et al.  Terahertz spectroscopy and imaging – Modern techniques and applications , 2011 .

[6]  Maya R. Gupta,et al.  Recent advances in terahertz imaging , 1999 .

[7]  Norihiko Sekine,et al.  The Need of Terahertz Cameras for Standardizing Sensitivity Measurements , 2014 .

[8]  Tetsuo Kan,et al.  Enantiomeric switching of chiral metamaterial for terahertz polarization modulation employing vertically deformable MEMS spirals , 2015, Nature Communications.

[9]  Naoki Oda,et al.  Uncooled bolometer-type Terahertz focal plane array and camera for real-time imaging , 2010 .

[10]  Xiang Zhang,et al.  Two‐dimensional electro‐optic imaging of THz beams , 1996 .

[11]  Naoki Oda,et al.  New thermally isolated pixel structure for high-resolution uncooled infrared FPAs , 2004, SPIE Defense + Commercial Sensing.

[12]  J. Kuhl,et al.  Velocity matching by pulse front tilting for large area THz-pulse generation. , 2002, Optics express.

[13]  Mikko Leivo,et al.  Passive three-colour submillimetre-wave video camera , 2013, Defense, Security, and Sensing.

[14]  F. Simoens,et al.  Broadband THz Uncooled Antenna-Coupled Microbolometer Array—Electromagnetic Design, Simulations and Measurements , 2012, IEEE Transactions on Terahertz Science and Technology.

[15]  Douglas J. Paul,et al.  Determination of complex refractive index of thin metal films from terahertz time-domain spectroscopy , 2008 .

[16]  Masayoshi Tonouchi,et al.  Cutting-edge terahertz technology , 2007 .

[17]  Erik Heinz,et al.  Next generation of a sub-millimetre wave security camera utilising superconducting detectors , 2013 .

[18]  X. Zhang,et al.  Free‐space electro‐optic sampling of terahertz beams , 1995 .

[19]  M. Nuss,et al.  Imaging with terahertz waves. , 1995, Optics letters.

[20]  H. Roskos,et al.  Real-time CMOS terahertz camera employing plane-to-plane imaging with a focal-plane array of field-effect transistors , 2013, 2013 38th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz).

[21]  M Usami,et al.  Development of a THz spectroscopic imaging system. , 2002, Physics in medicine and biology.

[22]  Franz X Kärtner,et al.  High conversion efficiency, high energy terahertz pulses by optical rectification in cryogenically cooled lithium niobate. , 2013, Optics letters.

[23]  K. Midorikawa,et al.  Real-time broadband spectroscopic terahertz imaging with diffraction grating and high-sensitivity terahertz camera , 2014, 2014 Conference on Lasers and Electro-Optics (CLEO) - Laser Science to Photonic Applications.

[24]  Naoki Oda,et al.  Palm-size and real-time terahertz imager, and its application to development of terahertz sources , 2013, Defense, Security, and Sensing.