A calibration apparatus in a wavelength division multiplexing system includes a sending module configured to send a first detection signal to a first multiplexing device; a receiving module configured to receive the first detection signal that passes through the first multiplexing device, and receive a second detection signal that passes through the first multiplexing device and a second multiplexing device; and a processing module configured to adjust a center frequency of the first detection signal, so that an adjusted center frequency of the first detection signal is aligned with a center frequency of the first multiplexing device, and adjust a center frequency of the second detection signal and the center frequency of the first multiplexing device, so that the center frequency of the first multiplexing device is aligned with the center frequency of the second detection signal.

The invention concerns an optoelectronic chip including a pair of optical inputs having a same bandwidth, and each being adapted to a different polarization, at least one photonic circuit to be tested, and an optical coupling device configured to couple the two inputs to the circuit to be tested.

This application provides a calibration apparatus and method, and a wavelength division multiplexing system. The calibration apparatus includes: a sending module, configured to send a first detection signal to a first multiplexing device; a receiving module, configured to receive the first detection signal that passes through the first multiplexing device, and receive a second detection signal that passes through the first multiplexing device and a second multiplexing device; and a processing module, configured to adjust a center frequency of the first detection signal, so that an adjusted center frequency of the first detection signal is aligned with a center frequency of the first multiplexing device, and adjust a center frequency of the second detection signal and the center frequency of the first multiplexing device, so that the center frequency of the first multiplexing device is aligned with the center frequency of the second detection signal.

A method is described for selecting fibers meeting requirements of a second minimum bandwidth at a second wavelength based on differential mode delay data measured at a first wavelength different from the second wavelength. The method comprises measuring the differential mode delay (DMD) data for the multimode fiber at the first wavelength, wherein the DMD data comprises output laser pulse data as a function of the radial position of an input laser pulse having the first wavelength; selecting the multimode fiber based on meeting requirements of the second minimum bandwidth at the second wavelength based on a second set of criteria, comprising a second criterion comprising: the radial dependence of the differential mode delay data measured at the first wavelength being within a pre-determined tolerance of a pre-determined reference function constructed by concatenating two or more even-order polynomials having the form:

[00001]${\left(r\right)}_{\mathrm{ref},k}=c_{0,k}+{c_{1,k}\left(\frac{r}{a}\right)}^2+{c_{2,k}\left(\frac{r}{a}\right)}^4.$

There are provided techniques for characterizing and testing a cable routing connection configuration connection arrangement comprising a plurality of optical fiber links connected between at least a first connection device at a first end and a second multi-fiber connection device at a second end. Test light is injected into one or more of the optical fiber links via corresponding optical fiber ports of the first connection device. At least one image of the second multi-fiber connection device is captured. Test light exiting the optical fiber link(s) through optical fiber port(s) of the second multi-fiber connection device is imaged as light spot(s) in the captured image. Positions on the second multi-fiber connection device that corresponds to the optical fiber port(s) are determined based on a pattern of the light spot(s) in the captured image. In some implementations, the provided techniques allow detection or verification of cable routing connection configurations at multi-fiber distribution panels.

A network element includes a transmitting amplifier configured to transmit to a first optical fiber, wherein the transmitting amplifier has a pump laser; and an optical monitor connected to a second optical fiber and configured to detect a portion of optical power thereon; wherein the pump laser is modulated to convey a signal to a second optical monitor in a second network element connected to the first optical fiber, when the transmitting amplifier is one of in a safety mode and has no input.

In this invention, a novel technique is introduced to measure chromatic dispersion (CD) in optical fibers. This technique is based on a relatively low-frequency optoelectronic oscillation (OEO) to provide fast, precise and low cost method for CD measurement that can be implemented easily in commercial instruments. In addition, another technique is presented to compensate for fiber thermal fluctuations during measurement which is based on a second simultaneously oscillating OEO. The proposed setup is implemented to measure the CD in normal single mode fibers with lengths of 40 km, 10 km, 1 km. Moreover, it is implemented to measure CD in 400 m of nonzero dispersion shifted fiber to test the system ability to resolve small chromatic delays. The proposed setup can resolve delays less than 0.1 ps/nm (which can be further improved by increasing the oscillation frequency) and measure CD with precision as low as 0.005 ps/nm.km as low as 20 seconds over a wavelength range from 1500 to 1630 nm. Further improvements may be possible by slightly better system design.

A method is used to select a multimode fiber meeting requirements of a first minimum bandwidth at a first wavelength and a second minimum bandwidth at a second wavelength different from the first wavelength. Differential mode delay (DMD) data is measured for the multimode fiber at the first wavelength. The DMD data comprises output laser pulse data as a function of the radial position of an input laser pulse having the first wavelength. The DMD data is transformed into mode group space, to obtain relative mode group delay data as a function of mode group. The multimode fiber is selected based on meeting requirements of the first minimum bandwidth at the first wavelength based on a first set of criteria, comprising a first criterion using as input the measured differential mode delay (DMD) data for the multimode fiber measured at the first wavelength. The multimode fiber is selected based on meeting requirements of the second minimum bandwidth at the second wavelength based on a second set of criteria, comprising: a second criterion using as input the relative mode group delay data. A related system is also described.

The purpose of the present disclosure is to provide a mode field diameter test method and test device that enable acquisition of a mode field diameter for an arbitrary higher-order mode. The present disclosure is a mode field diameter test method including: a test light incidence procedure for selectively causing test light to be incident in a mode subject to measurement, on one end of an optical fiber 10 under test; a far-field pattern measurement procedure for measuring a far-field pattern of the mode subject to measurement, with respect to a divergence angle at the other end of the optical fiber under test, by a far-field scanning technique; and a mode field diameter calculation procedure for calculating, using an equation, a mode field diameter from information about incident mode orders in the test light incidence procedure and the far-field pattern measured in the far-field pattern measurement procedure.

The invention concerns an optoelectronic chip including a pair of optical inputs having a same bandwidth, and each being adapted to a different polarization, at least one photonic circuit to be tested, and an optical coupling device configured to couple the two inputs to the circuit to be tested.