The 80th JSAP Autumn Meeting 2019

Presentation information

Oral presentation

4 JSAP-OSA Joint Symposia 2019 » 4.3 Ultrafast Optics and Laser Processing

[20p-E214-1~14] 4.3 Ultrafast Optics and Laser Processing

Fri. Sep 20, 2019 1:15 PM - 6:30 PM E214 (E214)

Takuro Ideguchi(Univ. of Tokyo), Sze Set(Univ. of Tokyo), Shinji Yamashita(Univ. of Tokyo)

3:45 PM - 4:00 PM

[20p-E214-6] A mid-IR QCL referenced to a fiber-based frequency comb applied to cavity ring-down spectroscopy for trace detection of CO2 isotopologues

〇(PC)Volker Thomas Sonnenschein1, Ryohei Terabayashi1, Hideki Tomita1, Keisuke Saito1, Masahito Yamanaka1, Norihiko Nishizawa1, Kenji Yoshida2, Tetsuo Iguchi1 (1.Nagoya Univ., 2.Sekisui Medical, Co., Ltd.)

Keywords:CRDS, frequency comb, beat-note

We perform abundance ratio measurements of CO2 isotopologues using a cavity ring-down spectrometer operating in the mid-infrared with a main focus on the radioisotope 14C. To make the technique more competitive with alternative techniques such as accelerator mass specrometery (AMS) and liquid scintillation counting (LSC) the noise level and systematic factors need to be further improved. Due to contaminants and interfering absorption lines the spectral fitting can be difficult without a precise frequency axis. To improve upon the frequency uncertainty we use a fiber based frequency comb in conjucntion with a nonlinear crystal to generate an offset-free DFG comb in the mid-infrared. This comb is used to detect the optical beat-note of our quantum cascade laser (QCL) system. Frequency tracking and stabilization via feedback to the lasers injection current is applied via a labview routine. With the improved calibration an better repeatability of isotope ratio measurements was confirmed.