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A physics-informed neural network (PINN) that combines deep learning with physics is studied to solve the nonlinear Schrödinger equation for learning nonlinear dynamics in fiber optics. A systematic investigation and comprehensive verification on PINN for multiple physical effects in optical fibers is carried out, including dispersion, self-phase modulation, and higher-order nonlinear effects. Moreover, both the special case (soliton propagation) and general case (multipulse propagation) are investigated and realized with PINN. In existing studies, PINN is mainly effective for a single scenario. To overcome this problem, the physical parameters (i.e., pulse peak power and amplitudes of subpulses) are hereby embedded as additional input parameter controllers, which allow PINN to learn the physical constraints of different scenarios and perform good generalizability. Furthermore, PINN exhibits better performance than the data-driven neural network using much less data, and its computational complexity (in terms of number of multiplications) is much lower than that of the split-step Fourier method. The results show that PINN is not only an effective partial differential equation solver, but also a prospective technique to advance the scientific computing and automatic modeling in fiber optics. [ABSTRACT FROM AUTHOR]

A theoretical study of optical properties of subwavelength-diameter silica fibers is presented, with an emphasis on the interplay between dispersion and nonlinearity. The normalized dispersion and effective nonlinearity are used to analyze the diameter-dependent relative strength at all wavelengths. The dispersion and nonlinearity length are calculated for guiding waveguide dimension design for possible applications. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2086–2090, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23552 [ABSTRACT FROM AUTHOR]

We demonstrate a highly birefringent photonic-crystal fiber by utilizing combined asymmetric core design and intentional stress-induced anisotropy. Based on spectral measurements of the polarization-mode interference, we measure that the fiber has a beat length of about 0.33 mm at 1545 nm. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 42: 498–500, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20348 [ABSTRACT FROM AUTHOR]

A wavelength switchable multiwavelength actively mode-locked fiber-ring laser based on highly nonlinear photonic crystal fiber (PCF) and polarization-dependent mode coupling to multimode-fiber Bragg grating (MMFBG) is proposed. Twenty meters of highly nonlinear dispersion-shifted PCF (DS-PCF) is inserted into the fiber ring cavity to suppress gain competition through the four-wave-mixing (FWM) effect. A mode scrambler is attached to the multimode fiber (MMF) to introduce a polarization-dependent mode coupling to the MMFBG. Through changing polarization in the cavity, stable and switchable one-wavelength, two-wavelength (wavelength spacing of 0.8 and 2.4 nm), and three-wavelength simultaneously actively mode-locked optical pulse trains at a repetition rate of 5 GHz are obtained. We show that high nonlinearity introduced by the nonlinear PCF in the cavity can improve significantly supermode suppression ratio (SMSR) of the multiwavelength pulses generated and a sidemode suppression ratio (SMSR) of 58 dB is realized. [ABSTRACT FROM AUTHOR]

We present a theoretical analysis of the total collectible optical power of an arbitrarily shaped multimode optical fiber probe for contact sensing where the signal from the analyte is emitted or scattered on the outside surface of the fiber tip. Calculation results and optimization parameters are given for spherical, parabolic, and cone-shaped fiber probes. This analysis can be used to guide the design and optimization of various fiber sensors, including fluorescence, surface plasmon resonance, and surface enhanced Raman sensors. [ABSTRACT FROM AUTHOR]

A novel and simple Erbium-doped fiber laser by using cascaded fiber Bragg gratings (FBGs) written in high-birefringence fibers for switchable multi-wavelength operation is proposed. Due to two-peak reflection with orthogonal polarizations of the FBG, the polarization hole-burning effect in the cavity is greatly enhanced. Experimental results show that the stable dual- and three-wavelength lasing operation with very narrow wavelength separation (∼0.39 nm) can be generated at room temperature. The configuration is simple and flexible. Only by adjusting polarization controllers (PCs), the laser can be switched among the stable single-, dual- and three-wavelength lasing operations. [Copyright &y& Elsevier]