Nonreciprocal photon blockade in a spinning microwave magnomechanical system through Kerr–magnon and optical parametric amplifier

We present a transient absorption (TA) setup with a broadband white-light from 600 to 1700nm without a detection gap. This TA setup differs from typical TA implementations in two distinct details. First, instead of seeding the 800nm fundamental laser beam directly into the white-light generation (WLG) crystal, we pump our yttrium aluminum garnet WLG crystal with the 2080nm idler of a home-built two-pass optical parametric amplifier pumped at 800nm. Second, we implement the B matrix referencing scheme introduced by Feng etal. to suppress the white-light fluctuations down to the shot-noise limit of our detector. As such, our implementation of the B matrix leads to a reduction of the root mean square of about an order of magnitude in the 1200-1700nm regime compared to the ratiometric referencing approach. Furthermore, we suppress baseline oscillations frequently encountered in TA by mitigating the effects of negative pixel correlation. To allow widespread implementation of the referencing scheme in the scientific community, we provide an introduction to the B matrix focusing specifically on data processing. The B matrix referencing scheme is easy to implement and is employed directly during data acquisition, thus maintaining similar alignment and measurement times compared to typical TA implementations. Finally, we show that the noise reduction provided by the B matrix referencing scheme allows for WLG schemes that would otherwise fluctuate too much to provide high-quality data in a reasonable amount of time, enabling the construction of more specialized TA experiments.

2.1 μm, 1.6-cycle mid-infrared pulse generated via spectrally temporally cascaded optical parametric amplification

Mercury contamination in water poses a serious threat to public health and ecosystems, demanding rapid and ultrasensitive detection at trace levels. We present, for the first time, an MXene-integrated fiber-optic Fabry-Pérot interferometer (MXene-FFPI) that demonstrates a mechanism-guided sensing platform for ultrasensitive Hg2+ detection at trace concentrations. High-quality mono- and bilayer Ti3C2Tx MXene nanosheets were synthesized via a minimally intensive layer delamination method, serving as efficient optical transducers and signal amplifiers. The sensing principle is based on interfacial redox-driven crystallization, in which Hg2+ ions are captured by MXene and converted into crystalline Hg2Cl2 nanoclusters, translating chemical interactions into amplified optical signals through modulation of the refractive index of the intracavity medium. Owing to the strong adsorption affinity and catalytic activity of MXene, chemical events are directly transduced into measurable interferometric responses. The MXene-FFPI exhibits an ultrahigh sensitivity of 5 pm/nM and a trace-level limit of detection (LOD) of 0.2 nM (0.04 ppb), more than 2 orders of magnitude lower than the WHO guideline limit for mercury in drinking water. This work establishes an MXene-interferometer nanophotonic architecture that converts interfacial reactions into amplified signals, providing a promising platform for ultrasensitive environmental monitoring and biomedical sensing.

Ionochromic optical sensor of amino-functionalized alginate brush grating.

In this Letter, we report a high-power, high-repetition-rate Ho:YLF chirped-pulse amplification (CPA) system driving a ZnGeP2 (ZGP) optical parametric generator and amplifier (OPG/OPA). The Ho:YLF CPA system operates at 100 kHz, delivering 48.1 W of average power at 2050.8 nm with a compressed pulse width of 5.0 ps. Using this source to pump the ZGP OPG/OPA, we obtain a 2.7 W signal light at 3402.1 nm and 0.64 W idler light at 5160.3 nm, with a pulse width of 2.5 ps for both. Moreover, continuous wavelength tuning ranges are achieved over 3051.2-3900.2 nm for the signal light and 4205.1-5160.3 nm for the idler light.

Certifying non-classicality and non-Gaussianity through optical parametric amplification

This review focuses on the fabrication and characterization of optical waveguides inscribed in GeO 2 –PbO glasses using femtosecond (fs) laser irradiation. Fs laser writing offers key advantages, such as three-dimensional structuring, high precision, and minimal thermal effects to the surrounding material, enabling the production of complex photonic devices within transparent substrates. The discussion covers different cases, each from a distinct sample and reported in separate works: a straight waveguide doped with Yb 3+ /Er 3+ , operating as an optical amplifier in the third telecommunications window, straight waveguides doped with Nd 3+ , with and without Ag nanoparticles and the role of the plasmonic effects on the optical properties at 1064 nm. The results of S-bend and Y-shaped configurations containing Ag nanoparticles are also reviewed due to their relevance for resonant ring and beam splitters, respectively. The role of larger radius is discussed as well as the best Y configuration with respect to the opening angle and separation between the arms. The quality factor (M 2 ) of the proposed architecture is used to evaluate the symmetry between the x and y axes that is relevant to indicate comparable light guidance. The review highlights different configurations as well as their optical properties and the potential applications for integrated photonics. • Review of recent advances in fs-laser-written dual-line waveguides in GeO 2 –PbO glasses • Fs-laser-written waveguides in GeO 2 –PbO glasses: a platform for integrated photonics • S-bend and Y-shaped architectures micromachined by fs laser in GeO 2 –PbO glasses • Waveguides with enhanced optical gain: the plasmonic effects of Ag nanoparticles

This study investigates drawing-induced effects on bismuth active centers (BACs) and optical amplification in Bi-doped phosphosilicate fibers operating in E and S bands. A twofold increase in BAC-related active absorption was observed, while the unsaturable loss remained nearly constant over a 100 °C drawing temperature. Unitary gain (dB/m) was found to increase linearly with drawing temperature, reaching ∼0.4 dB/m under bi-directional pumping when using 390 mW. With this pumping configuration, the amplifier's unsaturated peak gain was close to 35 dB using an optimum fiber length less than 100 m, demonstrating efficient amplification with high Bi concentration in those fibers.

High-average-power 1.62-μm optical parametric amplification using four-beam pumping

This work extends a previous investigation on plasmon enhanced optical gain in Nd 3+ doped TeO 2 -ZnO (TZ) pedestal waveguides incorporating gold nanoparticles (Au NPs) for applications at 1064 nm. The influence of Nd 3+ concentration and the role of a SiO 2 spacer layer on the plasmon assisted optical gain of Nd 3+ doped TZ were investigated. Thin films were deposited by RF magnetron sputtering, with the Nd 3+ concentration controlled by varying the number of Nd 2 O 3 pellets (1, 2, and 3). Pedestal waveguides with heights of ∼3.6 μm and widths ranging from 4 to 40 μm were characterized. Optical gain measurements at 1064 nm under 808 nm excitation showed that the lowest Nd 2 O 3 concentration achieved the highest relative gain (G R ) with enhancement of up to ∼80% due to Au NPs. Although higher Nd 3+ concentrations led to smaller improvements, attributed to self-absorption and non-radiative losses, the positive role of Au-NPs was observed. The introduction of SiO 2 spacer layers (25 or 100 nm) between the active core and Au NPs completely suppressed the plasmonic enhancement, confirming the importance of adequate distances between the rare-earth ions and the metallic NPs. These findings highlights the critical roles of dopant concentration and nanoscale Au NPs-core separation in maximizing plasmon assisted G R in Nd 3+ doped TZ based waveguides, providing guidance for the design of compact and efficient on-chip optical amplifiers. • Plasmon-assisted optical gain strongly depends on Nd 3+ concentration • Au nanoparticles deposited directly on the core: gain growth of up to ∼80% at 1064 nm • Optimal performance for the lowest Nd 3+ concentration: gain of up to 11 dB/cm • Au nanoparticles and the active core distance: relevance to promote plasmonic effects • Higher Nd 3+ concentrations reduce waveguide performance

We report on the realization and characterization of a high-efficiency diode-pumped solid-state amplifier integrated into a master oscillator power amplifier (MOPA) architecture. The system is specifically engineered to provide high-energy and throughput for next-generation space and earth observation missions, such as laser atmospheric profiling and altimetry. The PA is based on the optical amplification in a Brewster-cut Nd:YAG slab with an internal optical zigzag path to optimize the overlap efficiency between the pump and the flat-top extraction beam and adopts a multipass scheme based on multiplexing of the polarization state of the laser pulses. Operating at 1064 nm, the power amplifier demonstrates a robust energy extraction of more than 200 mJ per pulse in Q-switching (QS) regime, with a pulse repetition frequency (PRF) of 100Hz and root mean square (RMS) average power fluctuations lower than 0.25%. Addressing the critical challenge of thermal management, the system exhibits a residual thermal focal length above 1 m. To the best of our knowledge, this is the first side-pumped Nd:YAG slab amplifier with zigzag optical path employing a polarization multiplexed three-pass configuration exceeding 200 mJ of extraction energy and operating with a PRF of 100 Hz at 1064 nm in QS regime.

Sparse regularization algorithms for longitudinal power monitoring (LPM) often exhibit distortion in low-power regions and excessive smoothing at power discontinuities. To overcome these limitations, we propose a high-fidelity monitoring method based on physics-aware non-uniform sparse regularization. By incorporating asymmetric constraints and a spatial point decoupling strategy, the proposed method effectively suppresses non-physical power rise in low-power regions and preserves sharp transitions at the erbium-doped optical fiber amplifier (EDFA). With few measurements, the proposed method achieves a 0.58-dB reduction in root mean square error (RMSE) compared to the two-stage sparse regularization method and 1 km localization accuracy, significantly improving the fidelity and robustness of LPM.

The increasing demand for high-capacity optical networks necessitates innovative solutions for efficient traffic aggregation and dynamic routing. To address these challenges, this study presents the first experimental demonstration of a 400Gbps low polarization-sensitive multicast selective switch(MCS) implemented on an InP-based photonic integrated circuit (PIC). The switch integrates advanced active Semiconductor Optical Amplifier (SOA) technology and passive multimode interference (MMI) power splitters, achieving an on-chip gain exceeding 30 dB, a net fiber gain of 5.5 dB, and a noise figure (NF) of 6.6 dB, and a more than 35 dB switching extinction ratio. A comprehensive evaluation of the switch's performance in a 400Gbps dual-polarization(DP) coherent transmission setup demonstrates its ability to achieve error-free transmission with an optical signal-to-noise ratio (OSNR) penalty of less than 0.3 dB and a low polarization-dependent loss (PDL) below 1.8 dB.

Terahertz waves hold immense potential across diverse fields, including healthcare monitoring, biomedical imaging, precision navigation, high-speed communication, security screening, industrial quality control, and space exploration. However, the widespread adoption of terahertz technology has been hindered by the bulky, complex, and costly nature of existing systems. Here, we demonstrate gain-enhanced interband photomixing in quantum well (QW) PIN photodiodes as an efficient mechanism for frequency-tunable terahertz generation and detection, achieving significant improvements in power efficiency and sensitivity over the state-of-the-art. QWs embedded in PIN photodiodes-key elements of commercially available photonic integrated circuits (PICs)-enable monolithic integration of lasers, semiconductor optical amplifiers (SOAs), modulators, filters, demultiplexers, and other passive optical components. By establishing QW PIN photodiodes as the foundation of a Monolithically Integrated Terahertz Optoelectronic (MITO) platform, this work paves the way for compact, scalable terahertz optoelectronic systems with applications in high-speed data transfer, spectroscopy, and hyperspectral imaging. This advancement positions terahertz technology for widespread use, facilitating practical applications across remote sensing, communications, and medical diagnostics within portable devices.

Multimodal microscopy combining various imaging approaches can provide complementary information about tissue in a single imaging session. Here, we demonstrate a multimodal approach combining three-photon microscopy (3PM) and spectral-domain optical coherence microscopy (SD-OCM). We show that an optical parametric amplifier (OPA) laser source, which is the standard source for three-photon (3P) fluorescence excitation and third harmonic generation (THG), can be used for simultaneous optical coherence microscopy (OCM), 3P fluorescence and THG imaging. We demonstrate the system performance in deep mouse brains in vivo with an OPA source operating at 1620 nm center wavelength. We visualized small structures such as myelinated axons, neurons, and large fiber tracts in white matter with high spatial resolution noninvasively using linear and nonlinear contrast mechanisms at depth exceeding 1 mm in the intact adult mouse brain. Our results show that simultaneous OCM and 3PM at the long wavelength window can be conveniently combined for deep tissue imaging in vivo.

Strong-field laser physics and laser-plasma interactions require femtosecond vortex pulses that simultaneously deliver high pulse energy and high spatial intensity contrast (SIC). An optical parametric amplifier (OPA) is a promising energy scaling approach for femtosecond vortex pulses. However, vortex amplification is typically pumped with Gaussian or flat-top beams that retain nonzero intensity at the vortex center. Consequently, the intensity null is partially filled and the annular profile is distorted, resulting in a marked degradation of both the SIC and the ring-shaped structure. We introduce vortex-mode-matched pumping and flat-top vortex pumping as SIC-preserving strategies. To our knowledge, this is the first systematic SIC-centered study of ultrafast vortex-pulse OPA under different pump spatial modes. Numerical results show that vortex pumping effectively mitigates SIC degradation, while flat-top vortex pumping further improves energy extraction and achieves the best overall performance. We also establish experimentally actionable design rules by matching the pump and signal topological charges and optimizing the pump-to-signal beam-waist ratio. These research results offer valuable insights for the development of high energy and high-contrast vortex sources for supporting structured-light strong-field applications.

This work reports the experimental demonstration of a dual-wavelength L-band fiber ring laser for remote sensing applications. The system incorporates a polarization-sensitive semiconductor optical amplifier as the gain medium and two fiber Bragg gratings placed 25 km away from the laser cavity using standard single-mode fiber that serve both as wavelength-selective elements and sensing heads. Wavelength switching between single- and dual-channel lasing configurations is enabled by a simplified two-paddle motorized polarization controller. The system achieves optical signal-to-noise ratios exceeding 55 dB and power differences between lasing lines as low as 0.01 dB. To ensure long-term stability, an automatic control algorithm dynamically adjusts the polarization state in real time, compensating for environmentally induced polarization drift. The proposed setup provides a compact and robust solution for polarization-based wavelength switching in fiber lasers, with applications in the field of remote optical sensing.

Space-division multiplexing (SDM) is a key technology to overcome the capacity limit of single-mode fiber systems, using multiple spatial channels in few-mode fibers, multi-core fibers, and few-mode multi-core fibers. Few-mode multi-core erbium-doped fiber amplifiers (FM-MC-EDFAs) can compensate for transmission loss via either core or cladding pumping. While both pumping schemes have been studied, a detailed quantitative comparison is still lacking. In this work, we propose a more accurate numerical model for cladding-pumped, weakly coupled FM-MC-EDFAs and design three MCF configurations: a single-mode 7-core EDF, a 2-mode 7-core EDF, and a 4-mode 7-core EDF. The doping profile of the 4-mode fiber is optimized to reduce differential modal gain. Simulations comparing core and cladding pumping show that, when gain spectra are nearly identical in the C-band, the maximum noise figure (NF) differences are 0.734 dB, 0.75 dB, and 1.18 dB for the three designs, with minimum differences of 0.302 dB, 0.31 dB, and 0.374 dB at 1565 nm. Core pumping also achieves higher power conversion efficiency (PCE) in all cases: 41.92%, 43.83%, and 30.74%, respectively. This study provides practical insights for the design of SDM optical amplifiers.

ABSTRACT Carrier‐envelope phase (CEP)‐stable ultrashort pulse sources in the short‐wave infrared (SWIR) and mid‐infrared (MWIR) are central to modern ultrafast laser science. By combining robust CEP control with high average power and near‐single‐cycle pulse durations, these sources provide compact and versatile platforms for applications ranging from high‐resolution ultrafast spectroscopy and coherent imaging to strong‐field physics. This review surveys recent advances that are driving the broader adoption of coherent broadband few‐cycle infrared ultrafast systems, and we discuss frequency down‐conversion schemes based on difference‐frequency generation and intra‐pulse difference‐frequency generation, optical parametric generation and amplification, passive CEP‐stable architectures, and coherent multi‐octave infrared sources. Such ultrafast CEP‐stable sources provide unprecedented control over spectral tunability, phase stability, and pulse characteristics, fostering exciting opportunities across spectroscopy, imaging, and attosecond science.