Optical fiber characterization

Chamberlain, GE; Day, Gordon W.; Franzen, Douglas L.; Gallawa, R. L.; Kim, E M; Young, Matt

doi:10.6028/nbs.sp.637v2

Cited by 16 publications

(5 citation statements)

References 10 publications

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“…One possible method for achievement of an EMD in multimode fibers is to create launch conditions for a limited launch NA, which means in practice creating conditions for excitation predominantly of low-order axial modes rather than of high-order, leaky, and cladding modes. 16,17 In our experiment, the hollow-taper-based coupling method ensured perfect conditions within the test hollow waveguide for an EMD regime achieved by a limited launch NA, because the tapered funnel provided a smooth Gaussian-shaped profile of the output laser emission, and it possessed a low output NA and a smaller core diameter than the test fiber core diameter. Thus, in pulse dispersion measurements, the input pulse shape and mode distribution were kept constant ͑or in an EMD state͒ during the whole measurement.…”

Section: The Second Function Of the Funnel Was To Decrease Thementioning

confidence: 83%

“…The funnel provided conditions for achievement of a so-called steady-state or equilibrium-mode distribution ͑EMD͒ state of optical power within the test hollow waveguide. 16,17 One of the most important aspects of accurate and repeatable pulse dispersion measurement in multimode fibers is the dependence of the performance on the modal power distribution of the input laser beam, since different modes within the fiber have different pulse dispersion-as, for example, happens when a lens-based laser-to-fiber coupling is used, which technique provides sharp focusing of the strongly multimode input laser beam profile, ͓see Fig. 6͑a͔͒ and exciting of high-order modes in the test fiber.…”

Section: The Second Function Of the Funnel Was To Decrease Thementioning

confidence: 99%

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Pulse dispersion in hollow optical waveguides

Ilev

2005

Opt. Eng

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A study of laser ͑nearand mid-infrared͒ pulse dispersion in hollow waveguides is presented. We developed an analytical model to describe the pulse dispersion in hollow waveguides and compared our theoretical calculations with measurements done by us and also by two other groups. The pulse dispersion was experimentally measured for a short Q-switched Er:YAG laser in the nanosecond range and for femtosecond Ti:sapphire laser pulses transmitted by hollow optical waveguides. For analytical calculation of the pulse dispersion in these waveguides, a refined ray tracing program was developed. This approach took into account roughness of the internal reflecting and refracting inner layers. A comparison analysis between the measurements and calculations conducted at identical parameters demonstrates good correlation between theoretical and experimental results.

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Section: The Second Function Of the Funnel Was To Decrease Thementioning

confidence: 83%

Section: The Second Function Of the Funnel Was To Decrease Thementioning

confidence: 99%

Pulse dispersion in hollow optical waveguides

Ilev

2005

Opt. Eng

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“…A near-field setup is employed to demonstrate the light guiding capabilities of the machined diameter-reduced sapphire fiber 18 . Therefore, a two-centimeter-long section of the specimen is excited by means of laser radiation with a wavelength of 1550 nm and the exit end facet of the fiber is magnified and imaged onto the detector of an infrared camera.…”

Section: Resultsmentioning

confidence: 99%

High-precision micromachining of sapphire towards optical waveguiding structures using femtosecond lasers

Kefer

Zettl

Schmauß

et al. 2023

Laser-Based Micro- And Nanoprocessing XVII

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While sapphire is one of the most durable materials, its properties entail that high-precision machining, especially in the sub-millimeter regime, is still challenging. This contribution demonstrates and discusses novel femtosecond laser-based micromachining approaches for the fabrication of rotational-symmetric sapphire workpieces, specifically the generation of optical fibers by means of laser lathe of sapphire rods and the practical realization of windmill fibers. In addition, volume refractive index modification in planar sapphire substrates is presented to induce photonic crystal waveguides. The micromachined structures are comprehensively examined with respect to geometric fidelity, surface roughness, refractive index modification, and potential optical waveguiding properties. All micromachining approaches are done by means of frequency-doubled or frequency-tripled femtosecond laser radiation. Different laser optical setups including laser scanning head, spatial beam profilers including a spatial light modulator and axial rotatory movement of the specimen are employed for micro structuring and in-depth refractive index modifications. In particular for laser lathe, a sophisticated scanning pattern, in combination with an incremental axial rotatory movement of the specimen, allows for the precise diameter reduction of sapphire rods with 250 µm diameter to fibers with outer diameters of 25 µm. By supporting the workpiece with a V-groove fixture, multi-mode fibers with lengths up to 20 cm can be processed with an average surface roughness of 250 nm. Additionally, an adapted ablation scanning sequence enables the first practical demonstration of sapphire windmill fibers. Furthermore, using a spatial light modulator allows for the adaption of the laser propagation properties as to enable volume refractive index modifications with free-form arrangement. Hexagonal patterns of refractive index modifications surrounding a pristine waveguide core are fabricated and single-mode waveguiding at 1550 nm is verified. Finally, the possibility of integrating Bragg gratings into this photonic waveguide type is demonstrated.

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“…The telescope's collimating lens L1 is designed to generate a collimated beam that fully exploits the clear aperture of the focusing lens L2. This results in an effective numerical aperture of 0.46 and thus guarantees satisfaction of the overfilling condition in the free-space coupling situation [37]. The waveguide output is imaged onto an infrared camera (1460-1600 nm Near-Infrared Camera, Edmund Optics) through a microscope setup consisting of a 50x objective (M Plan Apo NIR HR 50X, Mitutoyo) and a tube lens (TTL200-S8, Thorlabs).…”

Section: A Near-field Analysismentioning

confidence: 99%

Lattice-Like Waveguides With Integrated Bragg Gratings in Planar Cyclic Olefin Copolymers

Kefer,

Pape,

Bischoff

et al. 2024

J. Lightwave Technol.

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This contribution demonstrates femtosecond laser direct writing of lattice-like waveguides in planar cyclic olefin copolymer substrates. Based on numerical simulation and experimental near-field analysis, stable single-mode waveguiding around wavelengths of 1550 nm is demonstrated. The waveguiding mechanism is based on a hexagonal array of laser-induced, positive refractive index modification lines. Thus, the lateral extension of the guided mode can be adapted by varying the fabrication parameters and, in consequence, the resulting crosssectional arrangement of the refractive index perturbations. With an optical attenuation of 2.2 dB•cm -1 around 1550 nm, the fabricated waveguides are well-suited for on-chip integrated photonic devices. Moreover, the waveguides can also be equipped with Bragg gratings to enable the application of the photonic platform as a sensing device. Depending on their length, the Bragg grating structures exhibit reflectivities of up to 99% and spectral widths down to 0.3 nm. The flexibility of the fabrication process and the sensing capabilities of the lattice-like waveguides with integrated Bragg gratings are underlined by an exemplary application study demonstrating a relative pressure sensor. For that, a photonic platform is micromilled to generate a 300 µm thick diaphragm and a reference pressure chamber. The strain introduced to the diaphragm by external pressure changes can then be quantified by the integrated photonic structures. This way, absolute pressure sensitivities of up to 38 pm•kPa -1 can be achieved in a relative pressure range from -60 to 100 kPa. The newlydeveloped lattice-like waveguides with integrated Bragg gratings are therefore well-suited for the realization of novel and adaptable photonic devices and sensors.

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Optical fiber characterization

Cited by 16 publications

References 10 publications

Pulse dispersion in hollow optical waveguides

Pulse dispersion in hollow optical waveguides

High-precision micromachining of sapphire towards optical waveguiding structures using femtosecond lasers

Lattice-Like Waveguides With Integrated Bragg Gratings in Planar Cyclic Olefin Copolymers

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