The effect of laser acupuncture on hypoxia tolerance and inflammation reaction in mice with optical fiber acupuncture needle intra body

Hypoxia is a disorder in which the tissues are not oxygenated adequately.The lack of oxygen may cause irreversible damage to the major organs such as the brain,heart and lungs.In severe cases,coma,seizures,and death may happen.In addition to the routine medication,acupuncture.treatment has been applied as a complementary treatment to counter hypoxia.In this paper,the optical fiber acupuncture needle was fabricated using the optical fiber imbedding into the metal capillary tube with needle tip,therefore made it easy to insert into the body for the laser treatment.The laser optical fiber needle treatment to the ST36 acupoint conducted with the laser.irradiation intra body.The normobaric hypoxia tolerance test results in mice show that the optical fber needle treatment to the ST36 acupoint with laser acupuncture appears to improve the tolerance to hypoxia.The mice treated with laser acupuncture expressed high level of IL-1βin serum.Our results suggest that laser optical fiber needle acupuncture may serve as a potential treatment for hypoxia.

Carbon-coated magnetic particles increase tissue temperatures after laser irradiation

Purpose:This work focused on the investigation the hyperthermia performance of the carboncoated magnetic particles(CCMPs)in laser-induced hyperthermia.Materials and methods:We prepared CCMPs using the organic carbonization method,and then characterized them with transmission electron microscopy(TEM),ultraviolet-visible(UV-Vis)spectrophotometry,vibrating sample magnetometer(VSM)and X-ray di®raction(XRD).In order to evaluate their performance in hyperthermia,the CCMPs were tested in laser-induced thermal therapy(LITT)experiments,in which we employed a fully distributedfiber Bragg grating(FBG)sensor to profile the tissue's dynamic temperature change under laser irradiation in real time.Results:The sizes of prepared CCMPs were about several micrometers,and the LITT results show that the tissue injected with the CCMPs absorbed more laser energy,and its temperature increased faster than the contrast tissue without CCMPs.Conclusions:The CCMPs may be of great help in hyperthermia applications.

Influence on Multimode Rectangular Optical Waveguide Propagation Loss by Surface Roughness

Optical scattering loss coefficient of multimode rectangularwaveguide is analyzed in this work.First,the effective refrac-tive index and the mode field distribution of waveguide modesare obtained using the Marcatili method.The influence onscattering loss coefficient by waveguide surface roughness isthen analyzed.Finally,the mode coupling efficiency for theSMF-Optical-Waveguide(SOW)structure and MMF-Optical-Waveguide(MOW)structure are presented.The total scatter-ing loss coefficient depends on modes scattering loss coeffi-cients and the mode coupling efficiency between fiber andwaveguide.The simulation results show that the total scatter-ing loss coefficient for the MOW structure is affected morestrongly by surface roughness than that for the SOW struc-ture.The total scattering loss coefficient of waveguide decreas-es from 3.97×10-2 d B/cm to 2.96×10-4 d B/cm for theSOW structure and from 5.24×10-2 d B/cm to 4.7×10-4 d B/cm for the MOW structure when surface roughness is from300nm to 20nm and waveguide length is 100cm.

Optimal Investment and Risk Control Strategy for an Insurer under the Framework of Expected Logarithmic Utility

In this paper, we consider an insurer who wants to maximize its expected utility of terminal wealth by selecting optimal investment and risk control strategies. The insurer’s risk process is modeled by a jump-diffusion process and is negatively correlated with the returns of securities and derivatives in the financial market. In the financial model, a part of insurers’ wealth is invested into the financial market. Using a martingale approach, we obtain an explicit solution of optimal strategy for the insurer under logarithmic utility function.

Recent progress of in‑fber WGM microsphere resonator

In-fber whispering gallery mode(WGM)microsphere resonators have received remarkable attention due to the superiorities of compact structure,high stability and self-alignment.As an in-fber structure,WGM microsphere resonators have been demonstrated in various applications,such as sensors,flters and lasers,which have signifcant impacts on modern optics.Herein,we review recent progress of in-fber WGM microsphere resonators,which involve fbers of diverse structures and microspheres of diferent materials.First,a brief introduction is given to in-fber WGM microsphere resonators,from structures to applications.Then,we focus on recent progresses in this feld,including in-fber couplers based on conventional fbers,capillaries and micro-structure hollow fbers,and passive/active microspheres.Finally,future developments of the in-fber WGM microsphere resonators are envisioned.

Two-photon 3D printed spring-based Fabry-Pérot cavity resonator for acoustic wave detection and imaging

Optical fiber microresonators have attracted considerable interest for acoustic detection because of their compact size and high optical quality.Here,we have proposed,designed,and fabricated a spring-based Fabry-Pérot cavity microresonator for highly sensitive acoustic detection.We observed two resonator vibration modes:one relating to the spring vibration state and the other determined by the point-clamped circular plate vibration mode.We found that the vibration modes can be coupled and optimized by changing the structure size.The proposed resonator is directly 3D printed on an optical fiber tip through two-photon polymerization and is used for acoustic detection and imaging.The experiments show that the device exhibits a high sensitivity and low noise equivalent acoustic signal level of 2.39 mPa∕Hz^(1∕2)at 75 kHz that can detect weak acoustic waves,which can be used for underwater object imaging.The results demonstrate that the proposed work has great potential in acoustic detection and biomedical imaging applications.

Distributed Vibration Sensor With Laser Phase-Noise Immunity by Phase-Extraction φ-OTDR

We have demonstrated a distributed vibration sensor based on phase-sensitive optical time-domain reflectometer (φ-OTDR) system exhibiting immunity to the laser phase noise. Two laser sources with different linewidth and phase noise levels are used in the φ-OTDR system, respectively. Based on the phase noise power spectrum density of both lasers, the laser phase is almost unchanged during an extremely short period of time, hence, the impact of phase noise can be suppressed effectively through phase difference between the Rayleigh scattered light from two adjacent sections of the fiber which define the gauge length. Based on the phase difference method, the external vibration can be located accurately at 41.01 km by the(φ-OTDR system incorporating these two lasers. Meanwhile, the average signal-to-noise ratio (SNR) of the retrieved vibration signal by using Laser I is found to be -37.7 dB, which is comparable to that of -37.5 dB by using Laser II although the linewidth and the phase noise level of the two lasers are distinct. The obtained results indicate that the phase difference method can enhance the performance of(φ-OTDR system with laser phase-noise immunity for distributed vibration sensing, showing potential application in oil-gas pipeline monitoring, perimeter security, and other fields.

Embedded whispering-gallery mode microsphere resonator in a tapered hollow annular core fiber

We propose and demonstrate a tapered hollow annular core fiber (HACF) coupler for excitation of whisperinggallery modes (WGMs) of an embedded microsphere resonator. The coupler is simply fabricated by fusion splicing of a segment of HACF with the single-mode fiber (SMF), and then improved by tapering the splicing joint to reduce the cone-apex angle. Therefore, the coupling efficiency from the SMF to the HACF is enhanced to excite various WGMs via evanescent field coupling. Normal positive, negative symmetrical Lorentzian and asymmetric Fano line shapes can be obtained by varying the resonator size and location. Another interesting phenomenon is observed that a higher Q-factor mode in a lower Q-factor mode has a contrast as high as 58. Temperature sensing with good stability is also demonstrated. This embedded WGM microsphere resonator in the tapered HACF is expected to promote environmental adaptability in practical applications due to its simplicity and

Over 255 mW single-frequency fiber laser with high slope efficiency and power stability based on an ultrashort Yb-doped crystal-derived silica fiber

A single-frequency distributed Bragg reflector (DBR) fiber laser at 1030 nm has been demonstrated using a 0.7 cm long homemade Yb:YAG crystal-derived silica fiber (YCDSF).The absorption and emission cross sections of the YCDSF are 4.93×10^(-20)cm^(2) at 980 nm and 1.1×10^(-20)cm^(2)at 1030 nm.Using this gain fiber,an over 255 m W continuous-wave lasing in the constructed laser has been obtained at single transverse and longitudinal mode operation.The slope efficiency and the pump threshold of the fiber laser were up to ~35%and as low as 25 m W,respectively.The fiber laser also demonstrated an optical signal-to-noise ratio of 79 dB and a beam quality factor of 1.016 in two orthogonal directions.Its power fluctuation at 210.5 m W was less than 0.85%of the average power within 13 h.Moreover,the relative intensity noise and linewidth of the laser are also investigated at the different pump powers.The results indicate that the single-frequency DBR fiber laser has potential applications in high-quality seed sources and high-precision optical sensing.

Theoretical aspects and sensing demonstrations of cone-shaped inwall capillary-based microsphere resonators

In this paper, a detailed theoretical study on the characteristics of cone-shaped inwall capillary-based microsphere resonators is described and demonstrated for sensing applications. The maximum, minimum, slope, contrast, and width of the Fano resonance are analyzed. As the transmission coefficient of the capillary resonator increases, the absolute value of the slope of Fano resonances increases to reach its maximum, which is useful for sensors with an ultra-high sensitivity. There occurs another phenomenon of electromagnetically induced transparency when the reflectivity at the capillary–environment interface is close to 100%. We also experimentally demonstrated its capability for temperature and refractive index sensing, with a sensitivity of 10.9 pm∕°C and 431 d B∕RIU basedon the Fano resonance and the Lorentzian line shape, respectively.

Broadband Acoustic Vibration Sensor Based on Cladding-Mode Resonance of Double-Cladding Fiber

We have proposed and demonstrated a double-cladding fiber (DCF) with cladding?mode resonance property for broadband acoustic vibration sensing. Since the fundamental mode in the core waveguide is able to be coupled to LP05 mode in the tube waveguide once the phase-matching condition is fulfilled, the transmission spectrum can exhibit a dip with a large extinction ratio. An acoustic vibration could induce the wavelength shift of such transmission spectrum, so that the intensity variation at a wavelength near the dip is coded with the information of the acoustic vibration signal. By demodulating the response of intensity variation, the frequency of the applied acoustic vibration signal can be recovered. Such a DCF-based sensor with an intensity modulation could measure the acoustic vibration with a broadband frequency range from 1 Hz to 400 kHz and exhibits the maximum signal-to-noise ratio (SNR) of ?80.79 dB when the vibration frequency is 20 kHz. The obtained results show that the proposed DCF-based acoustic vibration sensor has a potential application in environmental assessment, structural damage detection, and health monitoring.

Black Phosphorus-Film With Drop-Casting Method for High-Energy Pulse Generation From Q-Switched Er-Doped Fiber Laser

We have reported high-energy pulse generation from a Q-switched Er-doped fiber laser based on black phosphorus (BP) with a drop-casting method. Poly dimethyl diallyl ammonium (PDDA) is employed to protect BP. A passive Q-switching operation is achieved by using the BP/polyvinyl alcohol (PVA) film as the saturable absorbers (SAs). When the pump power increases from 130.4mW to 378mW, the repetition rate increases from 13.33kHz to 26.6kHz, and the pulse duration decreases from 10.67p,s to 7.11 (is. The maximum pulse energy is 468.03 nJ, to the best of our knowledge, which is the highest pulse energy produced from Q-switched fiber laser based on BP-SA at 1.5 pm. The obtained high-energy pulse demonstrates that BP/PVA film fabricated by such a drop-casting method can provide an ideal SA for high pulse energy generation from fiber lasers, and it has a potential application of remote sensing.

Wavelength-switchable vortex beams based on a polarization-dependent microknot resonator

We experimentally demonstrated a method of generating continuously wavelength-switchable optical vortex beams(OVBs) in an all-fiber laser. A polarization-dependent microknot resonator(MKR) functions as comb filter and accounts for the narrow linewidth(0.018 nm) of multiwavelength channels. The wavelength interval corresponds to the free spectral range of the MKR. We exploit a fused SMF–FMF(single mode fiber–few mode fiber) mode coupler to obtain broadband mode conversion and successfully achieve multiwavelength switchable OVBs. As far as we know, this is the first report about identical multiwavelength vortex beams with topological charges of 1. It has been verified that each channel of the vortex beams preserves the same orbital angular momentum(OAM) properties through their clear spiral interferograms. Multiwavelength vortex beams with identical OAM properties are desirable for multiplexing, exchanging, and routing to further improve the capacity of optical fiber transmission.

Monitoring and identifying pendant droplets in microbottle resonators

Optofluidic resonators are capable of characterizing various fluidic media.Here,we propose an optofluidic microbottle resonator(OFMBR)that is applied to generate pendant droplets,whose maximum mass is related to the liquid surface tension.Mass and type of droplets forming along the OFMBR stem can be monitored in real time by spectrum variation.As a pendant droplet grows,increased droplet gravity introduces a decreased coupling gap and compressive force between the tapered fiber and OFMBR,leading to a resonance wavelength shift.The operation mechanism of the proposed sensors is validated by theoretical simulation and experimental results.From the experimental spectra,a liquid mass sensor with maximum sensitivity of−3.34pm/mg is obtained,and distilled water and alcohol can be identified.This scheme provides a new thread for droplet generation as well as fluidic properties characterization.

Spectrally Flat Supercontinuum Generation in a ZBLAN Fiber Pumped by Erbium-Doped Mode-Locked Fiber Laser

We have experimentally demonstrated the flat supercontinuum(SC)generation using a 10-m-long ZrF4-BaF2-LaF3-AlF3-NaF(ZBLAN)fluoride fiber pumped by an erbium-doped mode-locked fiber laser incorporating carbon-nanotube-based saturable absorbers.In order to improve the spectral flatness of SC,the standardized single-mode fiber with different lengths is connected to the output of the mode-locked fiber laser before the pulse amplification.The generated SC with ZBLAN fiber exhibits the best spectral flatness with fluctuation less than 1.29 dB over the wavelength of 1571.8 nm−1803.1 nm,showing potential applications in optical sensing.