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Due to the slowdown of Moore's law, the integrated photonic devices have provided a route to promote the development of large‐scale optical communications with high performance. As one of the essential components of optical routers, an optical switch can fast transmit or block the optical signal. However, most of the integrated optical switches reported to date rely on thermo‐, magneto‐, or electro‐optical effects, which limit applications due to slow response times, large footprint, and complexity fabrication. Here, an integrated nonlinear optical switch designed by the inverse‐design method and fabricated on the SiN platform is introduced. The integrated optical switch is demonstrated with significant intensity‐dependent transmission at 1.5 µm waveband. The polarization‐depended capability is explored by using fundamental polarized lights (transverse electric and transverse magnetic, respectively), which exhibits opposite transmission change trends during the whole power range and opens potential applications such as photonic quantum information processing. In order to address the saturation of Kerr‐nonlinearity in SiN materials at high power, a MoS2/SiN hybrid integrated optical switch is fabricated by uniformly cladding few‐layer MoS2 on the surface of inverse‐designed region. That is demonstrated to enhance the nonlinear optical response of device efficiently and achieve more excellent switching capability at high power. [ABSTRACT FROM AUTHOR]

With the rising need for energy resources, considerable work has done for building novel energy storage technologies. Supercapacitors (SCs) and batteries are a highly competitive choice for electrochemical energy storage devices (EESDs) due to their ultrahigh power density, improved rate capability, long-term cyclability, and remarkable safety. Because of their novel properties such as high mechanical flexibility, large specific surface area (SSA), chemical stability, and superior electric and thermal conductivities, graphene-based nanomaterials (NMs) have attracted considerable attention as alternative electrode materials for EESDs. Graphene is gaining a lot of interest since it has amazing qualities including 230 000 cm2 V−1 s−1 charge mobility, 3000 W m−1 K−1 thermal conductivity, 2.3% visible light absorption, 130 GPa mechanical strength, and 2600 m2 g−1 specific surface area (SSA). Mechanical exfoliation, reduction of graphene-oxide, chemical vapor deposition (CVD), and epitaxial growth of graphene–NMs are some of the synthetic procedures that can change these characteristics. Despite much effort, the detailed screening of high-performance electrode materials, such as graphene-based NMs, is still necessary. We covered the recent advancements in graphene-based NM research and development for high-performance batteries and SCs for specific applications in the next generation and smart electronics in this study. First, we discuss rechargeable batteries, a new-concept based on graphene with high energy density, longer life, improved safety, and shape-diversity capabilities in order to meet the needs of future electronics. Second, we discuss SCs for the present advanced nanotechnologies that outperform batteries with respect to power density, cyclability, quick charging/discharging rates capability, straightforward principles, high activity of the charge circulation, and low maintenance expenditure, including electrical double layer capacitors (EDLCs) and pseudocapacitors (PCs). Finally, graphene-based electrodes used in ESDs with their prospects and problems are briefly reviewed. [ABSTRACT FROM AUTHOR]

Graphdiyne (GDY), which possess sp- and sp2-hybridized carbon and Dirac cones, offers unique physical and chemical properties, including an adjustable intrinsic bandgap, excellent charge carrier transfer efficiency, and superior conductivity compared to other carbon allotropes. These exceptional qualities of GDY and its derivatives have been successfully used in a variety of fields, including catalysis, energy, environmental protection, and biological applications. Herein, we focus on the potential application of GDY and its derivatives in the biomedical domain, including biosensing, biological protection, cancer therapy, and antibacterial agents, demonstrating how the biomimetic behavior of these materials can be a step forward in bridging the gap between nature and applications. Considering the excellent biocompatibility, solubility and selectivity of GDY and its derived materials, they have shown great potential as biosensing and bio-imaging materials. The unusual combination of properties in GDY has been used in biological applications such as "OFF–ON" DNA detection and enzymatic sensing, where GDY has a greater adsorption capacity than graphene and other 2D materials, resulting in increased sensitivity. GDY and its derivatives have also been used in cancer treatment due to their high doxorubicin (DOX) loading capacity (using-stacking) and photothermal conversion ability, and radiation protection since their initial biological use. The poor biodegradation rate of graphene demands the search for new nanomaterials. Accordingly, GDY has better biocompatibility and bio-safety than other 2D nanomaterials, especially graphene and its oxide, due to its absence of aggregation in the physiological environment. Thus, GDY-based nanomaterials have become promising candidates as bio-delivery carriers. Besides, GDY and GDY-based materials have also shown interesting applications in the fields of cell-culture, cell-growth and tissue engineering. Herein, we present a comprehensive review on the applications of GDY and its derivatives as biomedical materials, followed by their future perspectives. This review will provide an outlook for the application of graphene and its derivatives and may open up new horizons to inspire broader interests across various disciplines. Finally, the future prospects for GDY-based materials are examined for their potential biological use. [ABSTRACT FROM AUTHOR]

Integrated photonics are expected to replace the conventional free‐space optical systems, yet there remains a challenge of low nonlinear response due to small nonlinear refractive index and short interaction length. Here, the large‐area monolayer MoS2 is used to facilitate excellent nonlinear response, and a pump strategy is proposed with respect to the spontaneous four‐wave mixing in the visible spectral range. The external pump incident from the top resonates in the GaN microdisk resonator and is thoroughly absorbed by the monolayer MoS2 to generate the four‐wave mixing pump via the excitonic photoluminescence. Being driven by the internal photoluminescence pump and enhanced by the microcavity structure, it is validated that the proposed structure well suffices efficient degenerate spontaneous four‐wave mixing generation. Since the emission spectrum can be tailored through careful temperature control, this work holds a great potential in various functionalities, not only on‐chip visible light sources but also optical field control. [ABSTRACT FROM AUTHOR]

Ultrafast fiber lasers with a wide spectral range have huge demands for many applications. In this article, magnetron sputtering deposition (MSD) technique was utilized to prepare a new broadband microfiber based Sb thin film saturable absorber (SA), and ultrafast pulses in both 1.5 and 2 μm wavebands were generated with the integrated microfiber-based Sb thin film SA in erbium-doped fiber laser (EDFL) and thulium-doped fiber laser (TDFL), respectively. Pulse duration of 544 fs/972 fs and output power of 21.76 mW/36.1 mW centered at 1557 nm/1892 nm were respectively produced from stable mode-locked EDFL and TDFL. To the best our knowledge, this is the first time that ultrafast fiber lasers including both 1.5 μm and 2 μm wavebands were mode locked by a single microfiber-based Sb thin film SA. [ABSTRACT FROM AUTHOR]

We demonstrate the HfSe2 saturable absorber (SA) for the generation of ultrafast pulse laser. The HfSe2 SA device is fabricated by integrating HfSe2 nanosheets (NSs) with a microfiber. The material and optical characteristics of HfSe2 NSs show their high quality. The nonlinear optical absorption of HfSe2 SA is measured with a modulation depth of 5.8%. Stable soliton mode-locked laser based on HfSe2 SA is realized at the central wavelength of 1561.43 nm with pulse duration of 297 fs and the maximum pulse energy of 2.68 nJ. Our soliton fiber laser has a maximum output power of 48.5 mW with a high slope efficiency of 12.8%, which indicate that HfSe2 is a good candidate of SA for high efficient ultrashort pulses generation. [ABSTRACT FROM AUTHOR]

We demonstrate a compact in-fiber integrated microresonator based on a silica microsphere and microstructure fiber. Whispering-gallery-modes (WGMs) are effectively excited through evanescent field coupling between the silica microsphere and one of the input tube waveguides of negative curvature fiber. The WGM spectrum with the Q-factor of ∼2.56 × 103 and the extinction ratio of ∼15.2 dB is achieved. The transmission spectra evolution for 5 h reveals the long-term stability of WGM excitation. The experimental results indicate that the in-fiber integrated resonator has the advantages of high stability, high integration, robustness, alignment-free assembly structure, and low cost, motivating potential applications in the lab-in-fiber platform. [ABSTRACT FROM AUTHOR]

Two-dimensional layered materials have been widely utilized as nonlinear absorption materials to transfer continue-wave into pulse trains in fiber laser systems. Here, we prepare robust GaSe/GeSe composites with high power bearing capacity as saturable absorbers (SAs) and then investigate their nonlinear optical properties via broadband Z-scan measurement at 800 nm and 1550 nm, respectively. The modulation depths of GaSe/GeSe based SAs are measured to be 11.97% and 7.69% at 1550 nm. After incorporating the GaSe/GeSe SAs into an Erbium-doped fiber laser cavity, passively Q-switched pulse trains could be obtained with repetition rates changing from 83.58 to 136.78 kHz (70.41 to 161.65 kHz). The maximum output power and pulse energy are 52.1 mW/370.67 nJ (GaSe) and 21.6 mW/133.74 nJ (GeSe) under the maximum pump power of 600 mW. The results indicate that GaSe and GeSe possess outstanding thermal stability and could be employed as remarkable saturable absorption materials for high-energy pulses generation. [ABSTRACT FROM AUTHOR]

Despite extensive applications ranging from optoelectronic devices to flexible devices, two-dimensional layered materials used as ultrafast optical modulation materials have suffered from limited operation wavebands due to their intrinsic bandgap. Here, we investigate the nonlinear optical (NLO) response of group IIIA/IVA monochalcogenides XTe (X = Ga and Ge), which exhibit a remarkable saturable absorption response at a broadband wavelength. By using a liquid phase exfoliation technique, we prepare XTe nanosheets with few-layer thickness in a deionized water solvent and investigate their NLO responses at 800 nm, 1.5 µm, and 2 µm, respectively. Both GaTe and GeTe nanosheets exhibit ultrafast saturable absorption at 800 nm with 32.4 μJ (48.4 µJ) incident intensity. After preparing microfiber-based nanosheet optical modulators, their saturable absorptions are measured at 1.5 µm and 2 µm. The GaTe-SA possesses a little bit higher modulation depth (42.3% at 1.5 µm/30.7% at 2 µm) than the GeTe-SA (30.5% at 1.5 µm/8.3% at 2 µm) at two wavelengths. The lifetime of GaTe and GeTe nanosheets is measured to be 2.8 ps and 3.3 ps, respectively. In addition, we further examine their saturable absorption via incorporating them into an erbium- and a thulium-doped fiber laser system and obtain stably passively mode-locked pulse trains, respectively. The distinct NLO properties indicate a large potential of XTe nanosheets in the development of an ultrafast optical mode locker with a wideband operation wavelength. [ABSTRACT FROM AUTHOR]

In this letter, molybdenum ditelluride (MoTe2), a new member of the transition metal dichalcogenides family, has been characterized and fabricated as an optical modulator for the development of broadband wavelength tunable laser using a Tm3+-doped CaYAlO4crystal as a laser gain medium. The maximum average output power reaches 0.75 W with the shortest pulse width of about $0.69~\mu \text{s}$ and repetition rate of 70.9 kHz, which leads to a pulse energy of about $10.58~\mu \text{J}$ and peak power of 15.3 W. Keeping the MoTe2optical modulator inside the laser resonator and at the same time introducing an undoped YAG for wavelength tuning, wavelength tunable passively Q-switched laser operation with a wavelength range of about 112 nm has been demonstrated. This letter experimentally verifies the potential of the novel 2D material MoTe2as an optical modulator. At the same time, this letter paves the way toward the realizations of simple and compact wavelength tunable pulsed laser sources based on broadband 2D materials saturable absorbers. [ABSTRACT FROM AUTHOR]

We demonstrate a simple Fe3O4 nanoparticles (FONPs) based Q-switched fiber laser that is able to generate stable nanosecond pulses with single-wavelength or multiwavelength regimes. In the single-wavelength lasing scheme, the fiber laser generates 613-ns pulse with average output power of 41.2 mW, pulse energy of 321.3 nJ, and signal-noise-ratio of 54.4 dB. In the multiwavelength lasing scheme, stable pulse is achieved with 18-wavelength channels contained within the 3-dB bandwidth range. Our results prove that the FONPs can act as an effective Q-switch for high-energy pulse generation. [ABSTRACT FROM PUBLISHER]

We demonstrated a fiber-optic sensor using spheroidal-cavity-overlapped fiber Bragg grating (FBG) for simultaneous temperature and strain sensing. The spheroidal cavity is fabricated through splicing two sections of the photon-sensitive fiber together and located in the center of the FBG to act as a Fabry–Pérot interferometer (FPI). Experimental results demonstrate that the temperature sensitivity of the FPI part of the sensor is 0.67 pm/°C at the range of –70 °C–20 °C, and its strain sensitivity is 3.76 \mboxpm/\mu\varepsilon at the range of 0–500 $\mu\varepsilon$, while those of the FBG part are 8.40 pm/°C and 1.40 \mbox{pm} /\mu\varepsilon, respectively. The sensitivity difference ensures good simultaneous measurement performance. [ABSTRACT FROM PUBLISHER]

We establish an optical path difference (OPD) distribution model in a spatial scanned polarized low-coherence interferometry (LCI) considering the nonperpendicular incidence of light to explore the spatial frequency drift. Simulation shows that the OPD is no longer linearly distributed on a charged coupled device (CCD) and that the spatial frequency drifts approximately linearly as low coherent interference fringe (LCIF) shifts. A compensation process for spatial frequency domain analysis (SFDA)-based algorithm is proposed to avoid interference-order misidentification and consequent jump error. We verified our analysis and effectiveness of the proposed algorithm with an optical fiber Fabry–Pérot pressure sensing experiment. The measured spatial frequency drift agreed well with simulation results, and the interference-order misidentification was eliminated. [ABSTRACT FROM PUBLISHER]

A high precision demodulation method in frequency domain is proposed for a polarized low-coherence interferometer with location-dependent birefringence dispersion. By minimizing the frequency nonlinearity caused by dispersion effects, the proposed method avoids the jump errors of traditional frequency domain analysis method and exactly retrieve the absolute phase at multiselected-wavenumber point simultaneously, which makes it superior in accuracy, stability, and measurement range. We carried out experiments with an optical fiber Fabry–Pérot pressure sensing system to verify the effectiveness of the proposed method. The experiment result showed that the measured error was less than 0.049 kPa and the measurement range was widened to 285 kPa, which could be wider with suited experimental equipment and is no limit in theory. [ABSTRACT FROM PUBLISHER]

We investigated the fiber Bragg grating (FBG) thermal response in space vacuum thermal environment. The FBGs were packaged with 6061-T6 aluminum. The liquid nitrogen immersion experiment results show that its wavelength shift standard deviation is 0.76 pm for 217 h. The combination effect of vacuum and cryogenic temperature was studied by thermal cycling process in space environment simulator. The FBG sensors show accuracy better than 2% full scale, and the hysteresis errors are below 1%. It proves that these metal packaged FBG sensors can survive and meet the requirement of space measurement. [ABSTRACT FROM AUTHOR]

In article number 2000459, Gangyi Zhu, Junbo Yang, Peiguang Yan, and co‐workers demonstrate degenerate spontaneous four‐wave mixing operating in the visible spectral range in a GaN microdisk cavity which is driven by the A exciton emission in the monolayer MoS2 cladding. This work provides new insights for the research of on‐chip light sources and helps promote future applications such as broadband integrated light sources, correlated photon‐pair generation, and optoelectronic sensors. [ABSTRACT FROM AUTHOR]

In article number 2000459, Gangyi Zhu, Junbo Yang, Peiguang Yan, and co-workers demonstrate degenerate spontaneous four-wave mixing operating in the visible spectral range in a GaN microdisk cavity which is driven by the A exciton emission in the monolayer MoS SB 2 sb cladding. Microdisk Resonators: Photoluminescence-Induced Four-Wave Mixing Generation in a Monolayer-MoS2-Cladded GaN Microdisk Resonator (Laser Photonics Rev. 15(4)/2021) This work provides new insights for the research of on-chip light sources and helps promote future applications such as broadband integrated light sources, correlated photon-pair generation, and optoelectronic sensors. [Extracted from the article]

Group IVB transition metal dichalcogenides (TMDs) have attracted significant interests in photoelectronics due to their predictable superior physical properties compared to group VIB (Mo and W) TMDs. However, the nonlinear optical properties and ultrafast photonic devices based on group IVB TMDs remained unexplored so far. Herein, the nonlinear optical absorption of HfS2 nanosheets (NSs) prepared by liquid exfoliation is demonstrated. The usage of HfS2 as a new ultrafast photonic device for high‐energy and ultrashort pulse generation in a fiber laser is reported for the first time. A photonic crystal fiber (PCF) assisted deposition method is presented for the fabrication of an HfS2‐microfiber integrated saturable absorber (SA) device with precisely controllable light–matter interaction, which can benefit the output of the device. The HfS2‐microfiber SA device shows modulation depth of 15.7% and exhibits outstanding ultrashort pulse generation performance with pulse duration of 221.7 fs in the communication band. The experimental results suggest that HfS2 presents highly nonlinear optical absorption and can be developed into an excellent candidate of SA devices for the development of HfS2‐based ultrafast photonics. The nonlinear optical absorption of HfS2 nanosheets is demonstrated. Based on this nonlinear optical property, an HfS2‐based ultrafast photonic device is fabricated by integrating HfS2 with a microfiber. The usage of HfS2 for a new function of nonlinear optical materials in the generation of high‐energy and ultrashort pulses by fiber laser is reported. [ABSTRACT FROM AUTHOR]