Monitoring local temperature and longitudinal strain along a nonuniform AsSe-PMMA tapered fiber by Brillouin gain-profile tracing.

The local temperature and longitudinal strain at spatial resolution of 0.5% of the pulse-width equivalent length along a nonuniform AsSe-PMMA tapered fiber is investigated by a Brillouin gain-profile tracing method. This scheme uses a 20 ns pump pulse with the pulse-width equivalent length longer than the fiber under test (FUT) of 50 cm nonuniform AsSe-PMMA tapered fiber.

All-optical polarimeter for laser Stokes vector measurement using self-induced nonlinear phase modulation.

This paper utilizes an analytical model of polarization dependent frequency sideband generation via the Kerr effect in a highly nonlinear fiber to determine the state of polarization (SOP) of a laser by all-optical means. Theoretical analysis shows that the power of the n order sideband generated by the propagation of two lasers with distinct frequencies in the nonlinear medium is proportional to cos (α/2), where α is the angle between the normalized Stokes vectors representing the SOPs of the lasers on the Poincaré sphere. By tailoring the SOP of one laser acting as a reference and experimentally measuring the power of the first order sideband, the SOP of the laser under test is recovered with an error smaller than 10.

Sensitivity enhancement of fiber optical polarimetric sensors using self-induced nonlinear phase modulation via the Kerr effect.

This work presents an analytical model accounting for the impact of optical polarization on the generation of frequency sidebands by the Kerr effect in a highly nonlinear fiber. Theoretical analysis shows that for a relative polarization angle, α, between two input lasers expressed on the Poincaré sphere, the optical power of the n order sideband is proportional to cos (α/2). This theoretical result enables a novel all-optical technique for interrogating changes in polarization with higher sensitivity than conventional measurement schemes using linear polarizers.

Broadband ultrasound sensing based on fused dual-core chalcogenide-PMMA microfibers.

High-frequency ultrasound sensors are essential for high-resolution medical ultrasonic imaging and industrial ultrasonic non-destructive monitoring. In this paper, we propose highly sensitive broadband ultrasound sensors based on fused dual-core chalcogenide-polymethyl methacrylate (AsSe-PMMA) microfibers. We demonstrate that ultrasound response is determined by the differential slope of transmission spectra in the dual-core microfiber, which is verified by detecting the acoustic response in various microfibers of different tapering parameters.

All-optical intensity fluctuation magnification using Kerr effect: erratum.

We provide a correction to a figure in our published paper [Opt. Express28, 3789 (2020)10.1364/OE.

All-optical enhancement of minimum detectable perturbation in intensity-based fiber sensors.

We present a novel optical signal processing scheme for enhancing the minimum detectable environmental perturbation of intensity-based fiber sensors. The light intensity is first stabilized by inducing a sinusoidal intensity modulation and extracting the first-order sideband generated by self-phase modulation (SPM) in a nonlinear medium. The light with stabilized intensity is then sent through a sensor and the sensor induced power variation is magnified by first inducing a sinusoidal intensity modulation, then undergoing SPM, and finally extracting a higher-order sideband.

Stimulated Brillouin scattering in high-birefringence elliptical-core AsSe-PMMA microfibers.

In this Letter, we design and fabricate elliptical-core (ECORE) chalcogenide-polymethyl methacrylate (-PMMA) microfibers to explore the birefringence impact on stimulated Brillouin scattering. Numerical simulations based on the finite-element method and elastodynamic equation are utilized to calculate the phase and group birefringence and Brillouin gain spectra of the fundamental mode in three ECORE -PMMA microfibers at different core diameters. Experimentally measured and numerically calculated results show that as the core diameter of the minor axis of an ECORE microfiber with a ratio of 1.

Nonlinear resolution enhancement of an FBG based temperature sensor using the Kerr effect.

We demonstrate the enhancement of the resolution of a fiber optical sensor using all-optical signal processing. By sweeping the frequency of a tunable laser across a fiber Bragg grating, a signal corresponding to the reflection spectrum of the FBG is generated. If another laser with fixed power and frequency is launched into a highly nonlinear fiber along with the FBG-shaped signal, the Kerr effect gives rise to a number of frequency sidebands, where the power in each of the sidebands is proportional an integer exponent of the signal and pump powers.

High extinction ratio optical pulse characterization method via single-photon counting.

We present the characterization of high extinction ratio () square optical pulses using a photon counting technique, as other techniques only offer a limited range of measurement up to 60 dB. High- pulses are generated by applying a square pulse modulation on sinusoidally modulated optical signals, then inducing self-phase modulation (SPM) using the nonlinear Kerr effect and extracting an SPM-generated sideband. We measured a 10 ns Kerr-generated optical pulse exhibiting a 120.

Wide-range strain sensor based on Brillouin frequency and linewidth in an AsSe-PMMA hybrid microfiber.

We propose a wide-range strain sensor based on Brillouin frequency and linewidth in a 50 cm-long AsSe-polymethyl methacrylate (AsSe-PMMA) hybrid microfiber with a core diameter of 2.5 µm. The distributed information over the hybrid microfiber is measured by a Brillouin optical time-domain analysis (BOTDA) system.

Stimulated Brillouin scattering in a tapered dual-core AsSe-PMMA fiber for simultaneous temperature and strain sensing.

Chalcogenide fibers are currently being used widely in nonlinear optical signal processing, as they exhibit ultrahigh nonlinearity. Here, we propose a sensor based on stimulated Brillouin scattering for simultaneous temperature and strain measurement in a dual-core tapered -polymethyl methacrylate fiber using a Brillouin optical time-domain analysis system. Different Brillouin frequency responses under temperature and strain variations and the separation of Brillouin frequency shifts (BFSs) in two principal polarization axes are demonstrated experimentally over a 50-cm-long tapered dual-core hybrid microfiber.

All-optical intensity fluctuation magnification using Kerr effect.

We present a new all-optical method for the magnification of small-intensity fluctuations using the nonlinear Kerr effect. A fluctuation of interest is impressed onto a sinusoidally modulated optical signals (SMOS) and spectral sidebands are generated as the SMOS experiences self-phase modulation in a nonlinear medium. Magnification of these temporal variation is obtained by filtering one of the sidebands.

High birefringent Brillouin frequency shifts in a single-mode AsSe-PMMA microtaper induced by a transverse load.

We report high Brillouin frequency shifts of 0.08±0.02  MHz/N in a 60 cm AsSe-Poly(methyl methacrylate) (AsSe-PMMA) hybrid microtaper with 2 μm AsSe core and 100 μm PMMA cladding diameters under a transverse load.

Simultaneous generation of guided-acoustic-wave Brillouin scattering and stimulated-Brillouin-scattering in hybrid AsSe-PMMA microtapers: errata.

We would like to list the following errata that was found in the manuscript.

Simultaneous generation of guided-acoustic-wave Brillouin scattering and stimulated-Brillouin-scattering in hybrid AsSe-PMMA microtapers.

We demonstrate simultaneous generation of Stimulated Brillouin Scattering (SBS) and guided-acoustic-wave Brillouin scattering (GAWBS) from electrostriction of optical waves in a 60cm As Se -PMMA microtaper waveguide. The GAWBS in the microtaper couples with SBS through a complex energy transfer between weak Stokes and Anti-Stokes (AS) continuous waves in the presence of a high power pulsed pump wave. This results in an amplification of Stokes wave at 7.

Approach for temperature-insensitive strain measurement using a dual-core AsSe-PMMA taper.

A temperature-insensitive strain sensor is proposed and demonstrated based on a dual-core AsSe-polymethyl methacrylate (PMMA) taper. Longitudinal and transverse forces on the AsSe cores are induced by thermal expansion/contraction of the PMMA cladding due to an order of magnitude difference between the thermal expansion coefficients of AsSe and PMMA. At an optimal PMMA layer thickness, the wavelength shift caused by the thermally induced forces on the refractive index of the dual-core fiber cores counterbalances that caused by the thermally induced fiber length variation leading to temperature-insensitive transmission.

Self-inscribed antisymmetric long-period grating in a dual-core AsSe-PMMA fiber.

We report for the first time that transmission of optical pulses centered at a wavelength of 1550 nm through a tapered dual-core AsSe-PMMA fiber inscribes an antisymmetric long-period grating. The pulse power is equally divided between even and odd modes that superpose along the dual-core fiber to form an antisymmetric intensity distribution. A permanent refractive-index change that matches the antisymmetric intensity distribution is inscribed due to photosensitivity at the pulse central wavelength.

Enhancement of optical pulse extinction-ratio using the nonlinear Kerr effect for phase-OTDR.

We present a novel approach for the generation of high extinction-ratio square pulses based on self-phase modulation of sinusoidally modulated optical signals (SMOS). A SMOS in a nonlinear medium experiences self-phase modulation induced by the nonlinear Kerr effect leading to the generation of distinct sidebands. A small variation in the peak power of the SMOS leads to a large variation in the power of the sidebands.

Polarization dependence of the nonlinear interaction between sinusoidally modulated optical signals in a randomly birefringent optical fiber.

In this paper, polarization dependence of the nonlinear interaction between two sinusoidally modulated optical signals (SMOSs) in a randomly birefringent silica optical fiber is investigated analytically and experimentally. Vector analysis is performed on the nonlinear interaction between two orthogonally polarized or co-polarized SMOSs carried by identical or different laser wavelengths in a randomly birefringent silica optical fiber. Dependence of the nonlinear interaction on the polarization states of two SMOSs is investigated by analyzing the power of the first-order sideband as a result of the nonlinear interaction.

Sensitivity enhancement beyond the wavelength limit in a novel sub-micron displacement sensor.

We propose and demonstrate sub-micron displacement sensing and sensitivity enhancement using a two-frequency interferometer and a Kerr phase-interrogator. Displacement induces phase variation on a sinusoidally modulated optical signal by changing the length of the path that either of the signal's two spectral components propagates through. A Kerr phase-interrogator converts the resulting phase variation into power variation allowing for sub-micron displacement sensing.

Chromatic-dispersion measurement by modulation phase-shift method using a Kerr phase-interrogator.

We present a novel approach for the measurement of chromatic-dispersion in long optical fibers using a modulation phase-shift method based on a Kerr phase-interrogator. This approach utilizes a Kerr phase-interrogator to measure the phase variation of a sinusoidal optical signal induced by traveling in a fiber under test as the laser carrier wavelength and the sinusoidal signal frequency are varied. Chromatic-dispersion measurement for several fibers including a standard single-mode silica fiber and a dispersion-shifted fiber is experimentally demonstrated.

Displacement sensor based on Kerr induced phase-modulation of orthogonally polarized sinusoidal optical signals.

We present a novel short, medium, and long range displacement sensor using a Kerr phase-interrogator. Displacement induces relative phase variation between two orthogonally polarized sinusoidal optical signals. The Kerr phase-interrogator converts the phase variation into power variation through Kerr induced phase-modulation.

Broadband supercontinuum generation in As2Se3 chalcogenide wires by avoiding the two-photon absorption effects.

We report the generation of a broadband supercontinuum (SC) spanning from 1260 to 2200 nm using a 10 cm long As2Se3 chalcogenide (ChG) wire pumped at a wavelength of 1550 nm. Such a wide SC in As2Se3 is obtained by avoiding the effects of two-photon absorption normally observed at a wavelength of 1550 nm. For this purpose, the pump soliton is initially self-frequency shifted toward longer wavelength by means of the Raman effect in standard silica fiber before being launched into the ChG wire for spectral broadening.

Fabrication of Bragg gratings in subwavelength diameter As2Se3 chalcogenide wires.

The inscription of Bragg gratings in chalcogenide (As(2)Se(3)) wires with subwavelength diameter is proposed and demonstrated. A modified transverse holographic method employing He-Ne laser light at a wavelength of λ(w)=633 nm allows the writing of Bragg grating reflectors in the 1550 nm band. The gratings reach an extinction ratio of 40 dB in transmission and a negative photo-induced index change of Δn ∼ 10(-2).

All-optical polarization-mode dispersion monitor for return-to-zero optical signals at 40 Gbits/s and beyond.

The operation of a polarization-mode dispersion monitor insensitive to chromatic dispersion is demonstrated at 40 Gbits/s. The high-speed processing device is based on the Kerr effect and provides an optical power output as a reading of differential group delay. The monitor is compatible with return-to-zero modulation formats at data rates in excess of 40 Gbits/s and does not require the use of high-data-rate electronics.