arXiv subjects

Makoto Shoshin

Publications and source records attributed to Makoto Shoshin.

3 recordsLinked to original sources

arXiv2026

Ghost infrared spectroscopy with bright twin beams

Frequency-correlated light offers a route to mid-infrared (MIR) spectroscopy without direct spectral detection in the MIR. Previous MIR ghost spectroscopy has mainly relied on low-gain spontaneous parametric down-conversion (SPDC) and photon-pair coincidence measurements, where the limited photon flux has restricted acquisition times to longer than one minute. Here, we demonstrate ghost infrared spectroscopy using bright twin beams generated by high-gain parametric down-conversion (PDC). High-gain PDC amplifies vacuum fluctuations, producing a different pair of frequency-correlated random spectra in each pump pulse. This pulse-resolved stochastic emission is naturally matched to time-stretch detection, which records the spectrum of the correlated near-infrared telecom signal for every pulse, while the MIR idler is measured by bucket detection. Consequently, each pump pulse yields one paired projection measurement comprising a spectrally resolved reference and the corresponding bucket value. We reconstruct the transmission spectrum of a structured optical filter and the molecular vibrational absorption spectrum of liquid benzene near 3.3 um with millisecond-scale acquisition, in good agreement with Fourier-transform infrared spectroscopy. This reduces the acquisition time by four to five orders of magnitude compared with previous MIR ghost spectroscopy demonstrations. These results transform ghost spectroscopy from coincidence-based photon counting to high-flux analog correlation spectroscopy, establishing a practical architecture for high-speed computational infrared spectroscopy driven by a narrowband semiconductor laser.

physics.optics↗

arXiv2025

Light-programmable reorientation of the crystallographic c-axis of Tellurium thin films

Tellurium (Te), a two-dimensional material with pronounced structural anisotropy, exhibits exceptional electrical and optical properties that are highly sensitive to its crystallographic orientation. However, conventional synthesis techniques offer limited control over the in-plane alignment of Te's crystallographic c-axis, hindering large-scale integration. Here, we report a novel, non-contact method to dynamically manipulate the c-axis orientation of Te thin films using linearly polarized picosecond laser pulses. We show that the c-axis can be omnidirectionally reoriented perpendicular to the laser polarization, even in initially polycrystalline films. This reorientation is fully reversible, allowing for rewritable and spatially selective control of the c-axis orientation post-deposition. Our light-driven approach enables programmable anisotropy in Te, opening new avenues for reconfigurable optoelectronic and photonic devices, such as active metasurfaces and CMOS-compatible architectures.

cond-mat.mes-hall↗

arXiv2025

Fiber-based mid-infrared frequency-swept laser at 50 MScans/s via frequency down-conversion of time-stretched pulses

Increasing the sweep rate of mid-infrared (MIR) frequency-swept sources offers significant potential for various high-speed spectroscopy-based applications. While continuous-wave frequency-swept lasers have achieved sweep rates up to 1 MHz, a recently demonstrated time-stretched ultrashort pulsed laser has reached a significantly higher sweep rate, up to tens of MHz. However, the previous system relied on a bulky femtosecond optical parametric oscillator and produced only ~30 discrete spectral elements due to the use of a free-space time stretcher. In this work, we present a fiber-based frequency-swept MIR source that utilizes the frequency down-conversion of time-stretched near-infrared pulses, employing a compact mode-locked fiber laser and telecommunication fiber. As a proof-of-concept demonstration, we performed MIR spectroscopy of methane gas around 3.4 um at a rate of 50 MSpectra/s, capturing 220 spectral elements over a range of 19.0 cm-1. This compact and robust high-speed MIR frequency-swept laser system holds the potential for deployment in field applications.

physics.optics↗