arXiv subjects

Łukasz A. Sterczewski

Publications and source records attributed to Łukasz A. Sterczewski.

6 recordsLinked to original sources

arXiv2026

GHz-bandwidth InAs/InAsSbP barrier infrared detectors for the 3.0-3.7 μm spectral region operating at room temperature

The demand for fast mid-wave infrared photodetectors is fueled by high-rate free-space optical communication and optical frequency comb spectroscopy. To date, only a few multi-GHz photodetectors have shown sensitive room-temperature operation in the 3.0-3.7 μm band, yet their commercial availability remains scarce. In this work, we present the remarkable response speed of an InAs/InAsSbP nBp barrier detector - a type typically not associated with high-frequency operation. A weakly reverse-biased photodiode with a diameter of 121 μm achieves a -3 dB electrical bandwidth of 2.4 GHz and -20 dB bandwidth of 8.0 GHz. This is the best result in this class of mid-infrared photodetectors confirmed optically. High signal-to-noise photodetection is also demonstrated at frequencies exceeding 19 GHz. The relatively simple device structure (devoid of cascaded structure or type-II superlattice) was realized on the mature InAs material platform, which opens new perspectives for accessible, sensitive, multi-GHz photodetectors for the 3.0-3.7 μm spectral region.

physics.optics↗

arXiv2026

Microwave noise downconversion in interband cascade laser frequency combs

Chip-scale semiconductor laser frequency combs offer remarkable prospects for compact and power-efficient optical sensors. For the laser to be suitable for typical comb applications, its degree of coherence must first be assessed from a microwave self-mixing signal. Unfortunately, such measurements require scarcely available high-speed photodetectors with multi-GHz bandwidths and radio-frequency electronics. However, in this work, we demonstrate a simplified approach to comb coherence assessment for interband cascade lasers based on a relationship between easily-accessible MHz-frequency (baseband) noise and the multi-GHz-frequency intermode beat note. The downconversion of microwave noise to near-DC frequencies is found to originate intrinsically from the laser, which simultaneously acts as a frequency mixer due to electrical nonlinearities and a phase-to-amplitude noise converter due to the linewidth enhancement factor. Correlation between the electrical signals is explored in both frequency and time domains. Since this phenomenon is potentially universal in semiconductor lasers, it creates a new opportunity for frequency comb characterization, which may be particularly valuable in wavelength regions where fast photodetectors have limited availability.

physics.optics↗

arXiv2026

Incoherent Fourier transform spectroscopy with room-temperature coverage from NIR to THz

Despite the broadband nature of thermal light sources, optical spectroscopy over multiple spectral bands simultaneously remains challenging. Here, we demonstrate a practical Fourier transform infrared spectrometer (FTIR) that achieves room-temperature spectral coverage from 1 to 50 $μ$m (300--6 THz) in seconds using a single set of optics, with the long wave cutoff extendable to 90 $μ$m (3.3 THz) and the short wave to the ultraviolet (0.39 $μ$m). The interferometer employs a diamond plate beam splitter and windowless lithium tantalate (LTO) detector to probe the spectrum of combined incoherent sources operating at different temperatures. Applications of the instrument in modern chemometry, material science, and medicine are envisioned.

physics.optics↗

arXiv2024

Ultra-broadband room-temperature Fourier transform spectrometer with watt-level power consumption

Fourier-transform infrared spectroscopy (FTIR) has matured into a versatile technique with relevance for environmental monitoring, pharmaceutical research, and food safety applications. However, compared to other spectroscopic methods, it experiences slower progress in terms of power optimization, miniaturization, and adoption by industry. To overcome this limitation, we developed an ultra-broadband room-temperature FTIR instrument relying on commercially available components that offers a spectral coverage from 1.6 $μ$m to 31 $μ$m (9.7-190 THz) without changing optics at a single-Watt-level of electrical power consumption. To demonstrate the capabilities of the instrument, we measured atmospheric species in multiple spectral regions with better than 1.5 cm$^{-1}$ resolution.

physics.ins-det↗

arXiv2024

Dual-dispersion-regime dual-comb mode-locked laser

We report on the first solid-state dual-comb mode-locked laser simultaneously operating in different dispersion regimes. Due to the intrinsic polarization-multiplexing in a birefringent Yb:Ca$_3$NbGa$_3$Si$_2$O$_{14}$ (Yb:CNGS) gain medium, the laser emits two cross-polarized pulse trains with a repetition rate offset of ~4.8 kHz from a single cavity. We obtain dual pulse generation with 20-fold difference in the duration, by setting the net cavity group delay dispersion to cross zero across the emission band of the employed gain medium. While the duration of the soliton-like pulses experiencing anomalous dispersion amounts to 117 fs, the second laser output that is spectrally located in the normal dispersion region, is strongly chirped with a pulse duration of 2360 fs.

physics.optics↗

arXiv2019

Computational Doppler-limited dual-comb spectroscopy with a free-running all-fiber laser

Dual-comb spectroscopy has emerged as an indispensable analytical technique in applications that require high resolution and broadband coverage within short acquisition times. Its experimental realization, however, remains hampered by intricate experimental setups with large power consumption. Here, we demonstrate an ultra-simple free-running dual-comb spectrometer realized in a single all-fiber cavity suitable for the most demanding Doppler-limited measurements. Our dual-comb laser utilizes just a few basic fiber components, allows to tailor the repetition rate difference, and requires only 350 mW of electrical power for sustained operation over a dozen of hours. As a demonstration, we measure low-pressure hydrogen cyanide within 1.7 THz bandwidth, and obtain better than 1% precision over a terahertz in 200 ms enabled by a drastically simplified all-computational phase correction algorithm. The combination of the unprecedented setup simplicity, comb tooth resolution and high spectroscopic precision paves the way for proliferation of frequency comb spectroscopy even outside the laboratory.

physics.ins-det↗