Faraday rotation spectroscopy of nitrogen dioxide based on a widely tunable external cavity quantum cascade laser

Christian A. Zaugg; Rafal Lewicki; Tim Day; Robert F. Curl; Frank K. Tittel

doi:10.1117/12.874819

24 January 2011 Faraday rotation spectroscopy of nitrogen dioxide based on a widely tunable external cavity quantum cascade laser

Christian A. Zaugg, Rafal Lewicki, Tim Day, Robert F. Curl, Frank K. Tittel

Author Affiliations +

Proceedings Volume 7945, Quantum Sensing and Nanophotonic Devices VIII; 79450O (2011) https://doi.org/10.1117/12.874819
Event: SPIE OPTO, 2011, San Francisco, California, United States

Abstract

Faraday Rotation Spectroscopy (FRS) is a technique for the sensitive and selective detection of paramagnetic molecules or radicals such as NO, NO₂, O₂ or OH^-. Moreover FRS is suitable for atmospheric measurements due to the insensitivity to non-paramagnetic interfering molecules such as H₂O and CO₂. Experimental results of an FRS sensor for the NO₂detection employing an external-cavity quantum cascade laser (EC-QCL) are reported. The CW EC-QCL exhibits modehop free (MHF) tuning between 1600 cm^-1 and 1650 cm^-1. This allows targeting the optimum 4₄₁←4₄₀ Q-branch NO₂transition at 1613.25 cm^-1. A rotation of the polarization state of the initially linearly polarized laser light is observed when an AC magnetic field is applied to the NO₂ cell, placed between two nearly crossed Rochon polarizers. This rotation of the polarization state is proportional to the NO₂ concentration and can be determined by a photodetector located after the second polarizer. For long-term continuous measurements a second branch consisting of a detector and reference cell filled with 0.2 % NO₂ in N₂ is used to lock the laser to the selected NO₂ transition. A minimum detection sensitivity (1σ) of 1 parts per billion (ppbv) was obtained for a 1 sec lock-in time constant (TC).

Citation Download Citation

Christian A. Zaugg, Rafal Lewicki, Tim Day, Robert F. Curl, and Frank K. Tittel "Faraday rotation spectroscopy of nitrogen dioxide based on a widely tunable external cavity quantum cascade laser", Proc. SPIE 7945, Quantum Sensing and Nanophotonic Devices VIII, 79450O (24 January 2011); https://doi.org/10.1117/12.874819

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available