Optics letters最新文献

Enhancing carrier injection balance in near-infrared (NIR) to visible upconversion devices (UCDs) is crucial for improving efficiency and stability. This study presents the incorporation of an insulating polymer (polymethyl methacrylate (PMMA)) between an aluminum cathode and an electron transport layer to reduce excess electrons in a light-emitting layer, thus balancing electrode-injected electrons and NIR-generated holes. The optimized device achieved a fivefold increase in maximum luminance and upconversion efficiency compared to the control. Additionally, it demonstrated a fast optical response, a broad optical modulation range, and significant potential for bioimaging applications, achieving a maximum resolution of 1693 dpi. This approach provides an effective solution for enhancing carrier injection balance in UCDs.

We have theoretically investigated surface magnetoplasmons (SMPs) in an yttrium-iron-garnet (YIG) sandwiched waveguide. The dispersion demonstrated that this waveguide can support topological unidirectional SMPs. Based on unidirectional SMPs, magnetically controllable multimode interference (MMI) is verified in both symmetric and asymmetric waveguides. Due to the coupling between the modes along two YIG-air interfaces, the asymmetric waveguide supports a unidirectional even mode within a single-mode frequency range. Moreover, these modes are topologically protected when a disorder is introduced. Utilizing robust unidirectional SMP MMI (USMMI), tunable splitters have been achieved. It has been demonstrated that mode conversion between different modes can be realized. These results provide many degrees of freedom to manipulate topological waves.

The recent development of homochromatic attosecond streaking (HAS) has enabled a novel, highly precise method for ultrafast metrology of attosecond electron pulses as well as for real-time sampling of the instantaneous field waveforms of light transients. Here, we evaluate the potential of HAS as a method for precisely sampling the field waveform of non-phase-stabilized single-cycle transients of light. We show that the extreme nonlinearity of field emission and the core properties of HAS as a field sampling technique allow one to track the waveform of a single carrier-envelope phase (CEP) setting whose field dynamics results in the most energetic electron cutoff. Our results establish HAS as a robust, compact, all-solid-state method for characterizing light fields with attosecond-level precision and as a powerful tool in light field synthesis.

Terahertz polariton sources based on the stimulated polariton scattering (SPS) can generate the terahertz wave with a narrow linewidth and continuous tunability. A single SPS process has limited conversion efficiency due to the Manley-Rowe relation. In this Letter, we implement a dual-Stokes cavity structure within an intracavity terahertz parametric oscillator (TPO) to achieve a two-order cascaded SPS process. As a result, the dual-Stokes cavity TPO demonstrates an increment of 29% in terahertz output power compared to that obtained in the non-cascaded SPS configuration.

Mie resonances in dielectric particles play a crucial role in light-matter interaction, characterized by strong multipolar optical responses and low dissipative losses. This study presents an innovative methodology for precise discrimination of the size and quantity of deep-subwavelength microspheres by leveraging Fano resonances in coupled magnetic-dipole (MD) modes of a CaTiO₃-ceramic-particle triplet. The multifaceted characteristics of coupled MD resonances exhibit high sensitivity and specificity in detecting minute changes in the ambient environment. The alignment of theoretical and experimental results demonstrates the reliability and accuracy of our approach, highlighting its versatility and adaptability. This principle of deep-subwavelength measurement can also be appreciated at the nanoscale, indicating great potential for its applications in biological detection, chemical sensing, and environmental monitoring. The multifaceted Fano resonances of coupled Mie dipole modes establish a robust framework for future research in real-time monitoring and precision detection.

Thin-film lithium tantalate (TFLT) is attracting increasing attention in nonlinear generation of visible lasers due to its large second-order nonlinearity and reduced photorefractive effect. In this Letter, we design and fabricate a periodically poled TFLT waveguide for frequency doubling of a near-infrared laser operating at around 1064 nm. Continuous-wave 1.87-mW second-harmonic green light was obtained from the TFLT waveguide, and the nonlinear conversion efficiency is about 11.7%. The periodically poled TFLT waveguide exhibits a narrow wavelength acceptance bandwidth, a large nonlinear coefficient, and a stable output in the visible. The study present in this work will pave the way for the application of TFLT in nonlinear integrated photonics.

We report the generation of a multi-octave supercontinuum spanning from 350 nm to 1700 nm with exceptional spectral flatness and high conversion efficiency to both visible and near-infrared regions, by pumping a methane-filled hollow-core antiresonant fiber with 1030 nm laser pulses. The dynamics exhibited signs of both modulational instability (MI) and stimulated Raman scattering (SRS). Fiber lengths ranging from 15 cm to 200 cm were investigated along with gas pressures up to 50 bar and pump pulse durations from 220 fs up to 10 ps. The best supercontinuum, in terms of spectral width and flatness, was achieved with 220 fs pulses, 25 bar filling pressure, and 60 cm propagation length. Comparison with argon-filled fiber with matched nonlinearity and dispersion showed that the Raman contribution enhances the supercontinuum generation process compared to a pure modulational instability-based process. The average power was scaled up by increasing the pulse repetition rate to 50 kHz, but further scaling was hindered by linear and nonlinear absorption, leading to fiber damage.

Traditional non-interferometric quantitative phase imaging (QPI) methods often face challenges in realizing rapid and accurate imaging of large-phase samples, mainly due to slow convergence and dependence on object approximation models. In this Letter, we propose a new, to the best of our knowledge, non-interferometric QPI approach that leverages iterative Kramers-Kronig (KK) relations, named iKK-QPI, to achieve high-accuracy quantitative measurement of objects with large-phase values. In the current KK relations reconstruction framework, we impose real-part constraints on the cepstrum, breaking the restriction of weak scattering condition. With only a few iterations, iKK-QPI extends the phase range that can be reliably retrieved by non-interferometric QPI, exceeding the first-order Born and Rytov approximations. The capability of iKK-QPI is demonstrated by imaging a microlens array and COS-7 cells. We accurately reconstruct objects with large-phase ranges 6 rad (error < ± 5%), three times that of the KK relations-based method, opening up the possibility for non-interferometric QPI to measure biological and industrial samples with large-phase features.

We demonstrate high-energy nanosecond pulse amplification at ∼2.78 µm in a robust single transverse mode from a coiled large core low-numerical aperture (NA) Er:ZBLAN fiber amplifier. The highest energy achieved is 1.01 mJ from a 46 µm core Er:ZBLAN fiber, seeded with a preamplifier in a single-mode fiber 30 ns long pulses from a ring-cavity Q-switched Er:ZBLAN fiber laser. Near-diffraction-limited beams with M² = 1.09 were obtained using coiling-induced high-order mode filtering in a custom-fabricated 46 µm diameter and ∼0.064 NA core fiber. This constitutes, to the best of our knowledge, the highest-energy nanosecond duration pulses in a single transverse mode from an Er:ZBLAN fiber laser system to date.

We present the first ZBLAN-based polarization-dependent optical fiber coupler (OFC). The polarization extinction ratio (PER) reaches 2.5 dB/4.0 dB at the through-port/cross-port of the single-mode OFC. With an unpolarized light input, the OFC provides a coupling ratio of 73.5%/26.5% at the through-port/cross-port, with an excess loss of 1.47 dB at a wavelength of 1.918 μm. The OFC is used as the polarization-dependent element combined with nonlinear polarization evolution that triggers the pulsation of a mode-locked fiber laser. This approach generates fundamental solitons with a duration of 1.83 ps at a wavelength of 1.918 μm. The soft-glass OFC supports a power of at least 320 mW without damage. The polarization-dependent ZBLAN OFC is expected to play an important role in mid-infrared (MIR) fiber optics.