Dispersion effects in fiber optic interferometry

Journal ArticleAn extended analysis of the effects of uncompensated fiber dispersion on the fringe visibility of a fiber optic interferometer is developed, with particular emphasis on stellar interferometry. Both material and waveguide dispersion for single-mode, polarization-preserving fibers are considered. It is found that dispersion causes the fringe visibility curve to broaden, decrease in contrast, shift its centroid location, and in some cases become asymmetric. It is also sh own that when the interferometer is operated at wavelengths near 1300 nm, cancellation of second-order material and waveguide dispersion significantly improves the fringe visibility. The theoretical results are verified experimentally at both 672 nm and 1307 nm using a fiber optic Mach-Zehnder interferometer

Analysis of a distributed fiber-optic temperature sensor using single-photon detectors

We demonstrate a high-accuracy distributed fiber-optic temperature sensor using superconducting nanowire single-photon detectors and single-photon counting techniques. Our demonstration uses inexpensive single-mode fiber at standard telecommunications wavelengths as the sensing fiber, which enables extremely low-loss experiments and compatibility with existing fiber networks. We show that the uncertainty of the temperature measurement decreases with longer integration periods, but is ultimately limited by the calibration uncertainty. Temperature uncertainty on the order of 3 K is possible with spatial resolution of the order of 1 cm and integration period as small as 60 seconds. Also, we show that the measurement is subject to systematic uncertainties, such as polarization fading, which can be reduced with a polarization diversity receiver

High-resolution single-mode fiber-optic distributed Raman sensor for absolute temperature measurement using superconducting nanowire single-photon detectors

We demonstrate a distributed fiber Raman sensor for absolute temperature measurement with spatial resolution on the order of 1 cm at 1550 nm wavelength in a single-mode fiber using superconducting nanowire single-photon detectors. Rapid measurements are shown, with less than 60 s integration period, allowing the demonstration of temperature evolution in an optical fiber recorded at over 100 resolvable, 1.2 cm spaced positions along the fiber simultaneously. This distributed sensor has potential application as a primary reference standard, in which high-accuracy, high-spatial-resolution temperature measurements can be obtained without the need for a separate temperature calibration standard

Monolithic source of entangled photons with integrated pump rejection

We demonstrate a photon pair source with pump rejection filter on a single CMOS chip. Cascaded microring-based filters exhibit \u3e 95 dB pump extinction, providing a raw visibility in time-energy entanglement of 81.4% ± 2.3%