Numerical investigation of GHz repetition rate fundamentally mode-locked all-fiber lasers

GHz repetition rate fundamentally mode-locked lasers have attracted great interest for a variety of scientific and practical applications. A passively mode-locked laser in all-fiber format has the advantages of high stability, maintenance-free operation, super compactness, and reliability. In this paper, we present numerical investigation on passive mode-locking of all-fiber lasers operating at repetition rates of 1-20 GHz. Our calculations show that the reflectivity of the output coupler, the small signal gain of the doped fiber, the total net cavity dispersion, and the modulation depth of the saturable absorber are the key parameters for producing stable fundamentally mode-locked pulses at GHz repetition rates in very short all-fiber linear cavities. The instabilities of GHz repetition rate fundamentally mode-locked all-fiber lasers with different parameters were calculated and analyzed. Compared to a regular MHz repetition rate mode-locked all-fiber laser, the pump power range for the mode-locking of a GHz repetition rate all-fiber laser is much larger due to the several orders of magnitude lower accumulated nonlinearity in the fiber cavity The presented numerical study provides valuable guidance for the design and development of highly stable mode-locked all-fiber lasers operating at GHz repetition rates.National Science Foundation Engineering Research Center for Integrated Access Networks [EEC-0812072]; Technology Research Initiative Fund (TRIF) Photonics Initiative of the University of Arizona; National Natural Science Foundation of China (NSFC) [61575075]Open access journalThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

Current treatment strategies targeting histone deacetylase inhibitors in acute lymphocytic leukemia: a systematic review

Acute lymphocytic leukemia is a hematological malignancy that primarily affects children. Long-term chemotherapy is effective, but always causes different toxic side effects. With the application of a chemotherapy-free treatment strategy, we intend to demonstrate the most recent results of using one type of epigenetic drug, histone deacetylase inhibitors, in ALL and to provide preclinical evidence for further clinical trials. In this review, we found that panobinostat (LBH589) showed positive outcomes as a monotherapy, whereas vorinostat (SAHA) was a better choice for combinatorial use. Preclinical research has identified chidamide as a potential agent for investigation in more clinical trials in the future. In conclusion, histone deacetylase inhibitors play a significant role in the chemotherapy-free landscape in cancer treatment, particularly in acute lymphocytic leukemia

Fabrication of Metal-Semiconductor Heterostructures in Silicon Nanowires

The increasing demand for fossil fuels and the need to reduce greenhouse gases require clean energy sources and more efficient utilization of energy. Thermoelectric materials provide a means toward achieving these goals since they convert heat, including waste heat, directly into an electric potential difference. Metal-semiconductor heterostructures can work as Schottky barriers in thermoelectric materials to increase thermoelectric efficiency.In this project, nickel silicide phases were introduced into silicon nanowires (SiNWs) to build up the Schottky barrier. SiNW arrays were fabricated using a metal-assisted chemical process, creating SiNWs about 200 nm in diameter and 30ìm in length. Different methods were adopted for nickel deposition: electroless nickel deposition, electro nickel deposition, E-beam deposition, and thermal evaporation. The samples were examined by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results show that depositing nickel on SiNWs in an aqueous solution without electricity is a simple way to deposit nickel particles, and the morphology of nickel particles depends on the concentration of the deposition bath. However, an aqueous solution will cause oxidation of the SiNWs and hinder the formation of nickel silicide. To solve this problem, depositing nickel on SiNWs in organic solutions inside an oxygen-free glove box is a way to prevent oxidation, and nickel can diffuse into silicon substrates easily via annealing when there no oxidation layer on the surface of SiNWs. The dominant phase formed in these samples is NiSi2 after being annealed at 650°C for one hour in a tube furnace

pH-Responsive metal-organic framework encapsulated gold nanoclusters with modulated release to enhance photodynamic therapy/chemotherapy in breast cancer

Gold nanoclusters (AuNCs) with an ultra-small size, as new inorganic photosensitizers, have been shown to be promising in photodynamic therapy (PDT), but their application has been restricted due to short blood circulation. It is therefore important to develop stimuli-responsive AuNC-based nanoprobes to achieve highly efficient PDT. Here, metal-organic framework (MOF, ZIF-8) encapsulated AuNCs (AuNCs@MOF) were synthesized, and then they were loaded with doxorubicin (DOX) to obtain pH-responsive nanoprobes (AuNCs@MOF-DOX) with modulated release for enhanced PDT/chemotherapy. In an acidic tumor microenvironment, the structure of ZIF-8 collapsed, accelerating the release of the AuNCs and DOX in the tumor cells, and enhancing the performance of PDT/chemotherapy. Under irradiation with a 670 nm laser, a large amount of singlet oxygen was generated, and the release rate of DOX increased to 77.1% at a pH value of 5.5. By single PDT and single chemotherapy, the tumors were only partially inhibited, but they completely disappeared using the combination of PDT and chemotherapy. The prepared pH-responsive AuNCs@MOF-DOX nanoprobes with modulated release showed excellent PDT/chemotherapy performance, and will be important bi-functional nanoprobes for synergistic therapy

Wavelength Tunable Ho3+-Doped ZBLAN Fiber Lasers in the 1.2-mu m Wavelength Region

Wavelength tunability of continuous-wave holmium doped ZrF4-BaF2-LaT3-AlF3-NaF fiber lasers operating in the 1.2-arm wavelength region was investigated with a Littrow configuration. A wavelength tuning range of 1184-1198 nm was obtained from the fiber output port of the laser. The spectral width was measured to be around 0.02 nm over the entire tunable range and a maximum output power of 81.6 mW at 1192 nm was obtained at a pump power of 1.97 W. The wavelength tunable range was found to be limited by the transmission of the fiber-optic wavelength division multiplexer and coupler. A broader wavelength tuning range of 1177-1201 nm was obtained with a simpler fiber laser construction from the zero-order diffraction output of the bulk grating.NSF CIAN [EEC-0812072]; Photonics Initiative of University of Arizona; China Scholarship CouncilThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

C2SPoint: A classification-to-saliency network for point cloud saliency detection

Point cloud saliency detection is an important technique that support downstream tasks in 3D graphics and vision, like 3D model simplification, compression, reconstruction and viewpoint selection. Existing approaches often rely on hand-crafted features and are only applicable to specific datasets. In this paper, we propose a novel weakly supervised classification network, called C2SPoint, which directly performs saliency detection on the point clouds. Unlike previous methods that require per-point saliency annotations, C2SPoint only requires category labels of the point clouds during training. The network consists of two branches: a Classification branch and a Saliency branch. The former branch is composed of two Adaptive Set Abstraction layers for feature extraction and a Saliency Transform layer for learning saliency knowledge from the classification network. The latter branch introduces a multi-scale point-cluster similarity matrix for propagating the cluster saliency to each point within it, resulting in the prediction of point-level saliency. Experimental results demonstrate the effectiveness of our method in point cloud saliency detection, with improvements of 2% in both AUC and NSS compared to state-of-the-art methods

Temperature-Insensitive Refractive Index Sensor with Etched Microstructure Fiber

A Mach–Zehnder interferometer (MZI) based on an etched all-solid microstructure fiber (MOF) has been demonstrated. The MZI works on the basis of interference between the vibrant core and cladding modes in the MOF. The all-solid MOF has a heterostructure cladding composed of Ge-doped rod arrays and pure silica, and thus can support and propagate a vibrant cladding mode with a large mode area. When the outermost cladding of MOF is etched, the cladding mode becomes sensitive to the ambient refractive index (RI). The etched MOF can work as a sensing head for RI sensing. By comparing the interference spectra, the extinction ratio has remained stable at around 20 dB after the MOF was etched. The RI sensing characteristics of the MZI with an etched MOF have also been investigated. The results show that the RI sensitivity can reach up to 2183.6 nm/RIU with a low-temperature coefficient (<10 pm/°C)

Manufacturing a Long-Period Grating with Periodic Thermal Diffusion Technology on High-NA Fiber and Its Application as a High-Temperature Sensor

We demonstrated a kind of long-period fiber grating (LPFG), which is manufactured with a thermal diffusion treatment. The LPFG was inscribed on an ultrahigh-numerical-aperture (UHNA) fiber, highly doped with Ge and P, which was able to easily diffuse at high temperatures within a few seconds. We analyzed how the elements diffused at a high temperature over 1300 °C in the UHNA fiber. Then we developed a periodically heated technology with a CO2 laser, which was able to cause the diffusion of the elements to constitute the modulations of an LPFG. With this technology, there is little damage to the outer structure of the fiber, which is different from the traditional LPFG, as it is periodically tapered. Since the LPFG itself was manufactured under high temperature, it can withstand higher temperatures than traditional LPFGs. Furthermore, the LPFG presents a higher sensitivity to high temperature due to the large amount of Ge doping, which is approximately 100 pm/°C. In addition, the LPFG shows insensitivity to the changing of the environment’s refractive index and strain