We present a simple fiber-based single-arm spectral interferometer to measure directly the second-order dispersion parameter of short lengths of fiber (< 50 cm). The standard deviation of the measured dispersion on a 39.5-cm-long SMF28(TM) fiber is 1x10(-4) ps/nm, corresponding to 1% relative error, without employing any curve fitting. Our technique measures the second-order dispersion by examining the envelope of the interference pattern produced by three reflections: two from the facets of the test fiber and one from a mirror placed away from the fiber facet at a distance that introduces the same group delay as the test fiber at the measured wavelength. The operational constraints on system parameters, such as required bandwidth, wavelength resolution, and fiber length, are discussed in detail. Experimental verification of this technique is carried out via comparison of measurements of single mode fiber (SMF28(TM)) with published data and via comparison of measurements of a dispersion compensating fiber with those taken using conventional techniques. Moreover, we used this new technique to measure the dispersion coefficient of a 45-cm-long twin-hole fiber over a 70 nm bandwidth. It is the first time dispersion measurement on this specialty fiber is reported.

No abstract

We present low-coherence virtual reference interferometry (LC-VRI) for short length (<1 m) fiber dispersion characterization using a broadband LED source and a low-resolution spectrometer or spectrum analyzer. The LC-VRI is a simple and convenient alternative to balanced spectral interferometry (BSI), capable of measuring both first-and second-order dispersion directly from the interference pattern. The main advantage of using LC-VRI instead of BSI is that full characterization can be performed from a single spectral scan, without the need for precision control of the reference path. The technique is demonstrated for the characterization of SMF28 fiber and the results are compared with the manufacturer's specifications and to measurements obtained using BSI. The standard deviation of the first-and second-order dispersion is found to be on the order of 10 −3 ps and 10 −4 ps/nm, respectively, for both BSI and LC-VRI. IndexTerms-Chromatic dispersion, measurement techniques, optical fiber dispersion, optical fiber testing, optical interferometry.

We measured linear and quadratic dispersion on millimeter-length fibers, waveguides, and nanowires based on common-path spectral interferometry. We obtained the linear dispersion parameter, beta', with a relative precision of 1.45 x 10(-4), and extracted the quadratic dispersion parameter, beta'', from the Taylor expansion of beta' x beta'' values show a discrepancy of < 1% when compared with simulation as well as with measurement results obtained by a conventional Michelson interferometer. Using this method, we experimentally confirmed the sign inversion of the group velocity dispersion of AlGaAs nanowires for what is believed to be the first time.

We present the simultaneous measurement of first and second order dispersion in short length (< 1 m) few mode fibers (polarization and transverse) using virtual reference interferometry. This technique generates results equivalent to balanced spectral interferometry, without the complexity associated with physical balancing. This is achieved by simulating a virtual reference with a group delay equal to that of the physical interferometer. The amplitude modulation that results from mixing the interferograms, generated in both the unbalanced interferometer and the virtual reference, is equivalent to the first order interference that would be produced by physical balancing. The advantages of the technique include speed, simplicity, convenience and the capability for simultaneous measurement of multiple modes. The theoretical framework is first developed and then verified experimentally.