Fiber Bragg gratings written in highly birefringent microstructured optical fiber with a dedicated design are embedded in a composite fiber-reinforced polymer. The Bragg peak wavelength shifts are ...measured under controlled axial and transversal strain and during thermal cycling of the composite sample. We obtain a sensitivity to transversal strain that exceeds values reported earlier in literature by one order of magnitude. Our results evidence the relevance of using microstructured optical fibers for structural integrity monitoring of composite material structures.
A user‐friendly, fiber‐coupled, single‐photon source operating at telecom wavelengths is a key component of photonic quantum networks providing long‐haul, ultra‐secure data exchange. To take full ...advantage of quantum‐mechanical data protection and to maximize the transmission rate and distance, a true quantum source providing single photons on demand is highly desirable. This great challenge is tackled by developing a ready‐to‐use semiconductor quantum‐dot‐based device that launches single photons at a wavelength of 1.3 µm directly into a single‐mode optical fiber. In the proposed approach, the quantum dot is deterministically integrated into a nanophotonic structure to ensure efficient on‐chip coupling into a fiber. The whole arrangement is integrated into a 19ʺ compatible housing to enable stand‐alone operation by cooling via a compact Stirling cryocooler. The realized source delivers single photons with a multiphoton events probability as low as 0.15 and a single‐photon emission rate of up to 73 kHz into a standard telecom single‐mode fiber.
A user‐friendly, compact, and portable triggered single‐photon source operating in the telecom O‐band is demonstrated. The device provides single photons with g(2)(0) = 0.15 and a flux of up to 73 kHz at a standard physical‐contact single‐mode fiber connector output. A fully deterministic fabrication technology makes it the first application‐ready quantum‐dot‐based source to enable ultra‐secure data exchange in future fiber‐based quantum communication networks.
We report the generation of coherent octave-spanning supercontinuum in an all-fiber system, without any free-space optical components. The setup uses the femtosecond fiber laser as a pump and an ...all-normal dispersion microstructured fiber as a medium for supercontinuum generation. The generated spectrum is characterized both experimentally and numerically and shows a broad bandwidth (1.1-2.2 μm), a high signal to noise ratio reaching 100 at maximum, a high coherence (closing to 1), linear polarization and average output power up to 57 mW. The source is characterized by exceptional simplicity and does not require any alignment (the nonlinear fiber is spliced to the pump) which finally opens the path to outside-lab applications of supercontinuum radiation.
We experimentally characterized a birefringent side-hole microstructured fiber in the visible wavelength region. The spectral dependence of the group and phase modal birefringence was measured using ...the methods of spectral interferometry. The phase modal birefringence of the investigated fiber increases with wavelength, but its positive sign is opposite to the sign of the group modal birefringence. We also measured the sensing characteristics of the fiber using a method of tandem spectral interferometry. Spectral interferograms corresponding to different values of a physical parameter were processed to retrieve the spectral phase functions and to determine the spectral dependence of polarimetric sensitivity to strain, temperature and hydrostatic pressure. A negative sign of the polarimetric sensitivity was deduced from the simulation results utilizing the known modal birefringence dispersion of the fiber. Our experimental results show that the investigated fiber has a very high polarimetric sensitivity to hydrostatic pressure, reaching -200 rad x MPa(-1) x m(-1) at 750 nm.
We examine experimentally the influence of the fiber inelastic twist on polarimetric sensitivity to hydrostatic pressure and pressure sensitivity in a Rayleigh-scattering-based optical ...frequency-domain reflectometer (OFDR) for highly birefringent side-hole fibers. The fibers were drawn from the same preform with different spin pitches varying from 5 mm to 200 mm. We also demonstrate that the sensitivities of spun fiber can be estimated analytically based on its spin pitch, measured birefringence, and the sensitivity of the corresponding non-twisted fiber, showing good agreement with the experimental results. We proved that polarimetric sensitivity to pressure decreases with the shorter spin pitches, while distributed pressure sensitivity decreases for the one polarization eigenmode and increases for the second polarization eigenmode. Therefore, the spun-fibers can operate well as the polarimetric sensors of other physical parameters inducing circular birefringence even under varying pressure. Moreover, they can be used to obtain the desired difference between sensitivities for both polarization eigenmodes
We report on low-loss patch cords composed of a highly reproducible low-loss fusion splicing of photonic crystal fibers (PCFs) with a standard single mode fiber (SMF). Distinct from other papers in ...this area we report on the results for different types of PCFs, including LMA fibers with similar to a SMF core size and a mode field diameter (MFD), as well as polarization maintaining (PM) Bow-Tie PCF with an elliptical GeO 2 doped core and also a suspended-core (SC) PCF with a tiny core. We show that all studied splices between SMF and PCFs exhibit dispersive and non-reciprocal, in view of a light propagation direction, transmission losses. Defined as a larger decrease of a transmitted optical power comparing both propagation directions, achieved splicing losses, are equal to 0.46 ±0.03 dB, 0.34±0.01 dB, 0.67 ±0.17 dB and 3.09 ±0.36 dB at 1550 nm for LMA8, LMA10, Bow-Tie PCF and SC PCFs, respectively. Moreover, additionally to developed low-loss splicing, we report on low-loss patch cords for all mentioned above PCFs spliced on both ends with SMF pigtails ended with FC/APC connectors achieving the total losses at 1550 nm equal to 1.07 ±0.07 dB for LMA8, 0.72 ±0.20 dB for LMA10, 1.30 ±0.06 dB for Bow-Tie PCF, and 9.36 ±0.20 dB for SC PCF.
In this paper, the application of a fiber Bragg grating written in a highly birefringent side-hole elliptical core optical fiber for two-axial strain measurement is presented. Hybrid optical fiber ...structures achieved by combining large side-holes and elliptical core result in a very high birefringence of 1 × 10
and thus high initial Bragg peak spectral separation of 1.16 nm, as well as a very high transverse force sensitivity, of up to 650 pm/(N/mm) or even -1150 pm/(N/mm), depending on the fiber orientation with respect to the applied force. Due to the ~22 %m/m GeO
concentration in the core the fiber being highly photosensitive, which significantly simplifies FBG fabrication by UV illumination without the need for prior hydrogen loading, which worsens thermal stability. Finally, the developed FBGs written in the highly birefringent side-hole elliptical core optical fiber were embedded in the square composite plates and applied for strain measurements. Tests of two-directional four-point bending have shown usability of such FBG for two-axial in-plane strain measurement with a single FBG in iso-thermal conditions.
We report the first fully fiberized difference frequency generation (DFG) source, delivering a broadly tunable idler in the 6 to 9 μm spectral range, using an orientation-patterned gallium phosphide ...(OP-GaP) crystals with different quasi-phase matching periods (QPM). The mid-infrared radiation (MIR) is obtained via mixing of the output of a graphene-based Er-doped fiber laser at 1.55 μm with coherent frequency-shifted solitons at 1.9 μm generated in a highly nonlinear fiber using the same seed. The presented setup is the first truly all-fiber, all-polarization maintaining, alignment-free DFG source reported so far. Its application to laser spectroscopy was demonstrated by the absorption spectrum measurement of ν
band of methane in 7.5 - 8.3 µm spectral range. The system simplicity and compactness paves the way for applications in field-deployable optical frequency comb spectroscopy systems for gas sensing.
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