Low-birefringence Fiber Research Articles

Picosecond laser with Yb-doped tapered low birefringent double clad fiber

Abstract In this study, we present results of development fiber picosecond laser by using an active ytterbium tapered double clad optical fiber with mode field diameter of 35 μm and low intrinsic birefringence (1.45 * 10−8 rad m−1). We have demonstrated 1040 nm/50 ps optical source with tunable repetition rate (within range of 1–20 MHz) and an average power of 160 W (peak power 160 kW, 8 μJ per pulse) delivering Gaussian beam with excellent quality (M 2 ∼ 1.11/1.22).

Excitation of surface plasmon polaritons in a gold nanoslab on ion-exchanged waveguide technology.

Integrated metaphotonic devices has opened new horizons to control light-guiding properties at nanoscale; particularly interesting is the application of plasmonic nanostructures coupled to dielectric waveguides to reduce the inherent light propagation losses in metallic metamaterials. In this contribution, we show the feasibility of using ion-exchanged glass waveguides (IExWg) as a platform for the efficient excitation of surface plasmon polaritons (SPP). These IExWg provide high coupling efficiency and low butt-coupling with conventional dielectric optical waveguides and fibers, overcoming the hard fabrication tunability of commonly used CMOS-guiding platforms. We present a near-field scanning optical microscopy characterization of the propagation characteristics of SPP supported in a gold nanoslab fabricated on top of an IExWg. We found that the SPP can be only be excited with the fundamental TM photonic mode of the waveguide. Thanks to the low propagation loss, low birefringence, and compatibility with optical fibers, glass waveguide technology is a promising platform for the development of integrated plasmonic devices operating at visible and near infrared wavelengths with potential applications in single molecule emission routing or biosensing devices.

Theoretical assessment of the OTDR detector noise on plasma current measurement in tokamaks

In this paper, we propose a theoretical study dedicated to the assessment of plasma current measurement in magnetic confinement fusion reactors using a polarization optical time-domain reflectometer (POTDR) setup with a low-birefringence fiber used as the sensing fiber. We consider the general case of a non-uniform magnetic-field distribution along the sensing fiber. The numerical simulations, based on Jones formalism taking into account the OTDR noise, provide the measurement error as a function of the plasma current. The measurement performance is evaluated for an ITER-relevant sensor configuration. We demonstrate that a signal-to-noise ratio of 6dB, achievable in modern POTDRs, allows us to comply with the ITER requirements for plasma currents from 0 to 1MA, while for the 1 to 20MA range, the level is relaxed to 4dB.

Elimination of continuous-wave component in a figure-eight fiber laser based on a polarization asymmetrical NOLM

The operation of a nonlinear optical loop mirror (NOLM) with polarization-dependent transmission was analyzed to perform high-quality ultrashort optical pulses in a figure-eight fiber laser configuration. The design of the NOLM is based on a symmetrical coupler, a loop of highly twisted low-birefringence fiber and a quarter-wave retarder (QWR) to provide polarization asymmetry. Pedestal-free optical pulses were obtained by careful adjustment of the NOLM low-power transmission, which is easily realized in our setup by rotation of the QWR. The laser is capable of operating in both the conventional soliton and the noise-like pulse regimes. Optical pulses as short as 1.39 ps were observed at the fundamental repetition frequency of 0.8 MHz. The effectiveness of the proposed scheme is demonstrated by the elimination of low-intensity radiation at the laser output.

Effect of Raman gain on the state of polarization evolution in a low-birefringence fiber

Using the coupled nonlinear Schrödinger (CNLS) equation containing the Raman gain, the Duffing equation with Raman gain is derived, which is represented by the Stokes parameters, and then the elliptic integrals are used to compute the analytical solutions. This article focuses on the analysis of the Raman gain influence on the evolution of the polarization state when the optical waves are propagating in a low-birefringence fiber. Results show that the transmission cycle of the polarization evolution state can be changed due to Raman gain, if the input power and motion constants have a certain relationship.

Nonlinear polarization effects in optical fibers: polarization attraction and modulation instability [Invited

We review polarization stabilization techniques based on the polarization attraction effect in low-birefringence fibers. Polarization attraction or pulling may be based on cross-polarization modulation, on parametric amplification, and on Raman or Brillouin scattering. We also review methods for laser frequency conversion based on polarization modulation instabilities in low- and high-birefringence fibers, and photonic crystal fibers. Polarization instabilities in nonlinear fibers may also be exploited for sensing applications.

A Study on Different Types of Fiber Coils for Fiber Optic Current Sensors

We consider an interferometric fiber optic current sensor with a fiber coil operated in reflection and compare three different techniques to prepare the coil: thermally annealed coils, stress-free packaging of a bare low birefringent fiber in a fused silica capillary, and coils from highly birefringent spun fiber. In particular we theoretically and experimentally investigate how the fiber retarder that generates the near left and right circular light waves in the sensing fiber must be prepared for temperature compensation of the Faraday effect in the three cases. All three methods can achieve accuracy within ±<0.2% over an extended temperature range but they considerably differ in their practical challenges.

Influence of Raman effect on the state of polarization evolution in a low-birefringence fiber

In this paper, the linear polarization light satisfied nonlinear coupled differential equations containing the Raman effect are utilized in a low birefringence fiber. The coupling model equation satisfied by the Stokes parameters is derived by introducing the Stokes parameters. Poincaré sphere is used to analyze the influence of Raman scattering effect on the state of polarization evolution in the low-birefringence fiber. The results show that the state of polarization evolution can be changed and the polarization ellipticity can also be changed due to Raman scattering effect in the low birefringence fiber when between the input power and motion constants satisfy a certain relation.

Raman Effect on the Polarization State in Low-Birefringence Fiber

In low birefringence fiber, by solving the coupled nonlinear Schrodinger equations contained the Raman effect for satisfy right- and left-handed circularly po- larized light in the quasi-CW case, the relationship between the effective polarization beat length and changes of input power have been studied emphatically in low- and high input power situation considering the Raman effect or not. The results showed that the polarization state evolution cycles of the incident light can be changed and meanwhile the transmission distance of the incident light also can be changed due to Raman effect, regardless of the polarization of the incident light was along the slow axis or along the fast axis.

基于波长调制的低双折射光纤拍长测试

基于波长调制的低双折射光纤拍长测试

Development of fiber-optic current sensing technique and its applications in electric power systems

This paper describes the development and applications of a fiber-optic electric current sensing technique with the stable properties and compact, simple, and flexible structure of the sensing device. The special characteristics of the sensors were achieved by use of the special low birefringence fiber as the Faraday-effect sensing element and were also achieved with creation of sensing schemes which matched with the features of the fiber. Making use of the excellent features of the sensing technique, various current monitoring devices and systems were developed and applied practically for the control and maintenance in the electric power facility. In this paper, the design and performance of the sensing devices are introduced first. After that, examples of the application systems practically applied are also introduced, including fault section/point location systems for power transmission cable lines.

Study on spectral deviations of high-order optical fiber comb filter based on polarization-diversity loop configuration

In this paper, we investigate optical factors that may cause deviations of experimentally observed output spectra from theoretically predicted ones in a high-order optical fiber comb filter based on a polarization-diversity loop configuration. They include the wavelength dependency of half-wave plates (HWPs) contained in the filter for wavelength switching and the weak birefringence of single-mode fibers (SMFs) that connect optical components comprising the filter. The wavelength dependence of the HWPs is considered using the phase difference curve of a commercial HWP, which is a function of the wavelength of an incident light. In order to examine the effect of the SMF birefringence on the spectral characteristics of the high-order comb filter, the SMF is modeled as a low birefringence fiber whose principal axes are arbitrarily oriented with a certain small birefringence value. It is concluded from the calculation results that the SMF birefringence rather than the wavelength dependency of HWPs strongly affects the spectral characteristics of the filter including an extinction ratio, wavelength location, and spectral shape of the filter channel.

低双折射光纤中拉曼效应对增益谱的影响

低双折射光纤中拉曼效应对增益谱的影响

단일 모드 광섬유의 복굴절이 편광상이 배치구조 기반 고차 광섬유 빗살 필터의 출력 스펙트럼에 미치는 영향에 대한 고찰

In this paper, we investigated possible optical parameters causing deviation of experimentally observed output spectra from theoretically predicted results in a high-order fiber comb filter based on a polarization-diversity loop configuration. They include wavelength dependency of half-wave plates (HWPs) inserted in the filter for wavelength switching and the modal birefringence of single-mode fibers (SMFs) with which optical components comprising the filter are connected. In order to consider the effect of the modal birefringence of the SMF on a filter performance, it is modeled as a low birefringence fiber with an arbitrary orientation angle and birefringence. It is found from the simulation results that the modal birefringence of SMFs strongly affects the spectral characteristics of the filter and decreases the extinction ratio of the filter, compared with the wavelength dependency of HWPs. In particular, it is also confirmed that the spectral deviation and asymmetric distortions of side-lobes in narrow band transmission spectra result mainly from the modal birefringence of SMFs.

Coherent ultrashort pulse generation from incoherent light by pulse trapping in birefringent fibers

We investigated the nonlinear fiber phenomena of pulse trapping and amplification between incoherent light and an ultrashort soliton pulse in birefringent fibers both experimentally and numerically. Using the phenomena in a 1.4 km-long low-birefringence fiber, a coherent, nearly transform-limited, sech2-shaped, ultrashort pulse was generated from incoherent light from a super-luminescent diode. The average pulse energy and pulse width were 121 pJ and 640 fs, respectively. The estimated gain of this system was as large as 62 dB.

弱双折射光纤布喇格光栅反射偏振对温度响应特性的研究

The relationship between reflected polarization properties of apodized low-birefringence fiber Bragg gratings and temperature effect are analyzed theoretically.Numerical value simulates reflection spectrum of the apodized low-birefringence fiber Bragg gratings,polarization dependent loss and differential group delay curves with wavelength.The reflected center wavelength,polarization dependent loss and differential group delay which evolve with wavelength are measured under different temperature and the curves are drawn accordingly.The evolution of polarization dependent loss and differential group delay are analyzed according to the results of the experiment.In the experiment,reflected polarization dependent loss presents two peaks which shift to an equal extent as temperature changes and it indicates that polarization dependent loss has no significant difference.The maximum of difference group delay with temperature increase linearly shifts to long wavelengths and it is proved that the loss of orthogonal modes has changed equally.The synthetical theory analysis and experimental results show that the evolution of reflected polarization properties of apodized low-birefringence fiber Bragg gratings changes obviously with temperature changing and the changing of orthogonal modes presents proportional characteristics.

横向压力对弱双折射光纤光栅偏振相关损耗特性的影响

横向压力对弱双折射光纤光栅偏振相关损耗特性的影响

Polarization-Switching FBG Interrogator for Distributed Point Measurement of Magnetic Field Strength and Temperature

We report on the design and implementation of a novel optical fiber system for dual point measurement of magnetic field strength and temperature. The system incorporates a polarization switching technique that enables ratiometric processing of the orthogonal circularly polarized reflections from low-birefringence fiber Bragg gratings. High-resolution magneto-optical measurement of either static or dynamic magnetic fields may be achieved while retaining the capability for serial multiplexing and temperature measurement. The system provides a practical solution to intrinsic fiber point measurement of magnetic field, leading to potential applications in adverse environmental conditions, where electronic or extrinsic optical technologies are unsuitable.

Propagation stability of a chirped soliton in birefringent fibers

The propagation stability of a chirped soliton at anomalous dispersion region in birefringent fibers is numerically studied by using the split-step Fourier-method. It is found that initial linear chirp can change obviously the threshold value Ath above which soliton stably propagates in birefringent fibers, the Ath increases with the decrease of the polarization angle | /4- |. The positive chirp makes obviously the Ath smaller for group velocity mismatch parameter >0.5, the negative one makes the Ath larger for <0.5. The effect of initial positive chirp on the Ath is greater than that of negative chirp for high birefringent fibers, is less than that of negative chirp for low birefringent fibers.

Enhanced Efficiency of Multiple Four-Wave Mixing Induced by Modulation Instability in Low-Birefringence Fibers

Modulation instability (MI) induced by two strong beams and a weak beam via cross phase modulation is investigated. Multiple four-wave-mixing (FWM) processes associated with the MI in low-birefringence fibers are studied both theoretically and experimentally. The coupled-mode equations describing the MI-induced FWM nonlinear interactions between pump waves and sideband waves are derived. Theoretical and experimental results show that, on the assistance of MI, new optical frequencies can be generated quite efficiently from multiple FWM processes. More than eleven sidebands are experimentally achieved by the MI-driven multiple FWM processes. The transfer of energy from pumps to sidebands can be dramatically enhanced by the MI-induced parametric process. The experimental observations by using a piece of highly nonlinear dispersion-flattened photonic-crystal fiber confirm our theoretical predictions.