Experimental demonstration of a new near-infrared spectroscopy technique based on optical dual-comb: DC-NIRS Articles uri icon

publication date

  • July 2023

volume

  • 13

International Standard Serial Number (ISSN)

  • 2045-2322

abstract

  • We present a novel near-infrared spectroscopy technique based on Dual-Comb optical interrogation
    (DC-NIRS) applied to dispersive media. The technique recovers the frequency response of the
    medium under investigation by sampling its spectral response in amplitude and phase. The DC-NIRS
    reference and sample signals are generated using electro-optic modulation which offers a costeffective,
    integrable solution while providing high adaptability to the interrogated medium. A
    careful choice of both line spacing and optical span of the frequency comb ensures that the retrieved
    information enables the reconstruction of the temporal impulse response of the medium, known as
    the diffuse-time-of-flight (DTOF), to obtain its optical properties with a 70 ¿s temporal resolution
    and 32 ps photon propagation delay resolution. Furthermore, the DC-NIRS technique also offers
    enhanced penetration due to noiseless optical amplification (interferometric detection). The
    presented technique was demonstrated on a static bio-mimetic phantom of known optical properties
    reproducing a typical brain¿s optical response. The DTOF and optical properties of the phantom were
    measured, showing the capabilities of this new technique on the estimation of absolute optical
    properties with a deviation under 3%. Compared to current technologies, our DC-NIRS technique
    provides enhanced temporal resolution, spatial location capabilities, and penetration depth, with an
    integrable and configurable cost-effective architecture, paving the way to next-generation, noninvasive
    and portable systems for functional brain imaging, and brain-computer interfaces, among
    other. The system is patent pending PCT/ES2022/070176