Publications – Terahertz Sensors Group

K. Yamamura, G. Otake, A. Ouchi, D. Moraru, A. Nakamura and S. R. Tripathi. “Ellipticity enhancement of a terahertz wave circular polarizer made of 3D chiral metamaterial” IEEE Photonics Technology Letters, vol. 36, issue 7, pp. 457-460 (2024).
H. Ichikawa, K. Takeya and S. R. Tripathi, “Linear dichroism and birefringence spectra of bamboo and its use as a waveplate in the terahertz frequency region” Optical Materials Express, vol. 23, Issue 4, pp. 961-981, (2023) Selected as “Editor’s Pick” and “Cover Page” of Vol. 13, Issue 4, 2023 of the Optical Materials Express.
H. Uchida, T. Kawauchi, G. Otake, C. Koyama, K. Takeya and S. R. Tripathi, “Optical thin film coated organic nonlinear crystal for efficient terahertz wave generation” Scientific Reports, vol. 12, No. 15082, pp. 1-9, (2022)
K. Hashimoto, P. B. Ishai, E. Bründermann, and S. R. Tripathi, “Dielectric property measurement of human sweat using attenuated total reflection terahertz time domain spectroscopy” Biomedical Optics Express, vol. 13, Issue 9, pp.4572-4582 (2022)
K. Hashimoto and S. R. Tripathi, “Non-destructive identification of drugs in plastic packaging using attenuated total reflection terahertz time-domain spectroscopy” Optics, vol. 3, No. 2, pp. 99-106 (2022)
- Featured in Azo Optics:
  - Identifying Drugs in Packaging Using Spectroscopy
  - Detecting a Sample Using its Spectral Fingerprint
H. Tomita, K. Hashimoto, K. Takeya and S. R. Tripathi, “Development of a terahertz wave circular polarizer using a 2D array of metallic helix metamaterial” Optics Letters, vol. 46, Issue 9, pp. 2232-2235 (2021)
H. Uchida, C. Koyama, T. Takagi, P. B. Wang, T. Kamei, S. R. Tripathi, K. Kawase and K. Takeya, “Enhanced terahertz wave generation from Cytop antireflection-coated DAST crystal” Journal of Infrared, Millimeter and Terahertz Waves, vol. 41, pp. 552-556, (2020)
Shun Takagi, Shogo Takahashi, Kei Takeya and Saroj R. Tripathi, “Influence of delay stage positioning error on signal-to-noise ratio, dynamic range and bandwidth of terahertz time-domain spectroscopy” Applied Optics vol. 59, Issue 3, pp. 841-845 (2020). This article has been selected as one of the most downloaded articles from Applied optics and Biomedical Optics Express (research on terahertz optics and imaging) in 2020. OSA is providing complimentary access to this article till the end of May 2021.
Kei Takeya, Keisuke Matsumura, Ryohei Takahashi, Takashi Fukui, Saroj R. Tripathi and Kodo Kawase, “Optical parameters of gas hydrates for terahertz applications” Journal of Infrared, Millimeter and Terahertz Waves, vol. 41, pp. 375-381, (2019)
Kei Takeya, Ryohei Takahashi, Takashi Fukui, Saroj R. Tripathi, and Kodo Kawase, “Terahertz characterization of propane hydrate “Japanese Journal of Applied Physics, vol. 58, 032203, (2019)
Saroj R. Tripathi, Paul Ben Ishai and Kodo Kawase, “Frequency of the resonance of human sweat duct in normal mode of radiation” Biomedical Optics Express, vol. 9, Issue 3, 1301-1308, (2018)
Saroj R. Tripathi, S. Takahashi, K. Kinumura and K. Kawase, “Frequency of resonance of human sweat duct in different modes of operation” Proceedings of SPIE, Vol. 10492, 1049201- (1-5) , 2018
Kei Takeya, Tsubasa Minami, Hiroyo Okano, Saroj R. Tripathi, Kodo Kawase, “Enhanced Cherenkov phase matching terahertz wave generation via a magnesium oxide doped Lithium Niobate ridged waveguide crystal” APL Photonics, Vol. 2, 016102, (2017)
Saroj R. Tripathi, Yuya Sugiyama, Kosuke Murate, Kazuki Imayama and Kodo Kawase, “Terahertz wave three-dimensional computed tomography based on injection-seeded terahertz wave parametric emitter and detector” Optics Express, vol. 24, Issue 6, pp. 6433-6440 (2016)
Mikiya Kato, Saroj R. Tripathi, Kosuke Murate, Kazuki Imayama and Kodo Kawase, “Non-destructive drug inspection in covering materials using a terahertz spectral imaging system with injection-seeded terahertz parametric generation and detection” Optics Express, vol. 24, Issue 6, pp. 6425-6432 (2016)
Paul Ben Ishai, Saroj R. Tripathi, Kodo Kawase, Alexander Puzenko and Yuri Feldman, “What is the primary mover of water dynamics ? ” Physical Chemistry Chemical Physics (PCCP). vol. 17, pp. 15428-15434 (2015).
Saroj R. Tripathi, Eisuke Miyata, Paul Ben Ishai and Kodo Kawase, “Morphology of human sweat ducts observed by optical coherence tomography and their frequency of resonance in the terahertz frequency region” Scientific Reports vol. 5, No. 9071, pp 1- 7, (2015)
Saroj R. Tripathi, Kousuke Murate and Kodo Kawase, “High power terahertz wave generation via non-linear optical processes“, A. J. Physics vol. 24, No. 3, pp 363-368, (2015)
Yu Guan, Manabu Yamamoto, Toshiyuki Kitazawa, Saroj. R. Tripathi, Kei Takeya and Kodo Kawase, ”A concealed barcode identification system using terahertz time domain spectroscopy”, Journal of Infrared, Millimeter and Terahertz wave vol. 36, Issue 3, pp. 298-311, (2015)
Yusuke Taira, Saroj R. Tripathi*, Kousuke Murate, Shin’ichiro Hayashi, Koji Nawata, Hiroaki Minamide and Kodo Kawase, “A terahertz wave parametric amplifier with a gain of 55dB” IEEE Transactions on Terahertz Science and Technology, vol. 4, No. 6, pp. 753-755, (2014) * Corresponding author.
Kei Takeya, Hiroyo Okano, Saroj R. Tripathi and Kodo Kawase, “Development of measurement and analysis techniques using terahertz waves and their sources” (Invited article) IEICE Transactions on Electronics. vol. J97-C, No. 11, pp. 420-428, (2014)
Kousuke Murate, Yuusuke Taira, Saroj R. Tripathi, Shin’ichiro Hayashi, Koji Nawata, Hiroaki Minamide and Kodo Kawase ” A high dynamic range and spectrally flat terahertz spectrometer based on optical parametric process in LiNbO3” IEEE Transactions on Terahertz Science and Technology, vol. 4, No. 4, pp. 523- 526, (2014).
Saroj R. Tripathi, Yuusuke Taira, Shin’ichiro Hayashi, Kouji Nawata, Kousuke Murate, Hiroaki Minamide and Kodo Kawase, “Terahertz wave parametric amplifier” Optics Letters, vol. 39, No. 6. pp 1649-1652, (2014).
Saroj R. Tripathi, Kousuke Murate, Hirohisa Uchida, Kei Takeya and Kodo Kawase, “A fiber laser pumped, high-power terahertz wave source based on optical rectification of femtosecond pulses in 4-Dimethylamino-N-methyl-4-Stibazolium Tosylate crystal ” Applied Physics Express (APEX), vol. 6, pp. 072703-1, (2013).
Hirohisa Uchida, Saroj R. Tripathi, Koji Suizu, Takayuki Shibuya, Takashi Osumi and Kodo Kawase “Widely tunable broadband terahertz radiation generation using a configurationally locked polyene 2-[3-(4-hydroxystyryl)-5,5-dimethylcyclohex-2-enylidene] malononitrile crystal via difference frequency generation” Applied Physics B: Lasers and Optics, vol. 111, issue 3, pp. 489-493, (2013).
Saroj R. Tripathi, Makoto Aoki, Masanori Takeda, Toshiaki Asahi, Iwao Hosako and Norihisa Hiromoto, “Accurate complex refractive index with standard deviation of ZnTe measured by terahertz time domain spectroscopy” Japanese Journal of Applied Physics, vol. 52, No. 4, 042401-4 (2013).
Saroj R. Tripathi, Hiroo Inoue, Tsuyoshi Hasegawa and Kodo Kawase, “Non-destructive inspection of chloride ion in concrete structures using attenuated total reflection of millimeter waves“, Journal of Infrared, Millimeter and Terahertz Waves, vol. 34, issue 2, pp. 181-186, (2013).
Makoto Aoki, Saroj R. Tripathi, Masanori Takeda and Norihisa Hiromoto, ”Angle dependent condensing efficiency of Winston cone in terahertz region”, Infrared Physics and Technology, vol. 56, pp. 8-11 (2013)
Saroj R. Tripathi, Hidehiro Ogura, Hiroyuki Kawagoe, Hiroo Inoue, Tsuyoshi Hasegawa, Kei Takeya and Kodo Kawase, “Measurement of chloride ion concentration in concrete structures using terahertz time domain spectroscopy (THz-TDS)“, Corrosion Science, vol. 62, pp. 5-10 (2012)
Makoto Aoki, Saroj R. Tripathi, Masanori Takeda and Norihisa Hiromoto, “Passive imaging and emissivity measurement with a 4K cryocooled terahertz photoconductive detector“, IEICE Electronics Express, vol. 9, no. 5, pp. 333-338 (2012)
Masanori Takeda, Saroj R. Tripathi, Makoto Aoki and Norihisa Hiromoto, “Random error in intensity spectrum measured with THz-TDS – No relation to the intensity fluctuation of fs laser “, Advanced Materials Research , vol. 222, pp.213-216 (2011)
M. Aoki, S. R.Tripathi, M. Takeda and N. Hiromoto, ”THz passive imaging using high sensitive THz photoconductive detector” IEEJ issue on light application and visual science (LAV), vol. 24, pp. 27-31, 2010.
S. R.Tripathi, M. Aoki, M. Takeda and N. Hiromoto, ”Random error estimation in optical constants of sample with sharp absorption features measured by terahertz time domain spectroscopy” IEEJ issue on light application and visual science (LAV), vol. 24, pp. 55-60, 2010.
Saroj R. Tripathi, Makoto Aoki, Kento Mochizuki, Toshiaki Asahi, Iwao Hosako and Norihisa Hiromoto, “Properties and modeling of random errors in optical parameters measured with THz-TDS,” Journal of Japan Society of Infrared Science and Technology. vol. 19, No. 1 & 2, pp. 77-84 (2010)
Saroj R. Tripathi, Makoto Aoki, Kento Mochizuki, Iwao Hosako, Toshiaki Asahi and Norihisa Hiromoto, “Practical method to estimate the standard deviation in absorption coefficients measured with THz time-domain spectroscopy,” Optics Communications, vol. 283, issue 12, pp. 2488-2491 (2010)
Saroj R. Tripathi, Makoto Aoki, Kento Mochizuki, Toshiaki Asahi, Iwao Hosako and Norihisa Hiromoto, “Random error estimation in refractive index measured with the terahertz time domain spectroscopy,” IEICE Electronics Express, vol. 6, no. 23, pp. 1690-1696 (2009)