A deformometer includes: a cavity body; entry and exit optical cavity optics, such that the optical cavity produces filtered combined light from combined light; a first laser that provides first light; a second laser that provides second light; an optical combiner that: receives the first light; receives the second light; combines the first light and the second light; produces combined light from the first light and the second light; and communicates the combined light to the entry optical cavity optic; a beam splitter that: receives the filtered combined light; splits the filtered combined light; a first light detector in optical communication with the beam splitter and that: receives the first filtered light from the beam splitter; and produces a first cavity signal from the first filtered light; and a second light detector that: receives the second filtered light; and produces a second cavity signal from the second filtered light.

The test device of the present invention is configured to test the continuity and polarity of a plurality of fibers housed by a cable that extends between the multi-fiber connectors on either end of the cable. In its most basic form, the test device of the present invention includes first and second light sources; an optical splitter positioned between the second light source and the connector at the first end of the cable housing the plurality of fibers under test; and a receiver and configured for optical communication with the second end of the cable. The first light source creates a first light pattern, which is distinct from a second light pattern created by the second light source.

An optical fiber array includes a support, a single-mode optical fiber and a plurality of multimode optical fibers, the single-mode optical fiber and the multimode optical fibers being arranged on the support, and a polarizing plate provided on an end face of the support, wherein the single-mode optical fiber has polarization maintaining characteristics, an end face of the single-mode optical fiber and end faces of the multimode optical fibers face the end face of the support, and the polarizing plate covers the end faces of the multimode optical fibers.

An apparatus includes an element to transmit a partial amount of first light guided through the M cores of a target object and second light guided through M optical waveguides, and to reflect remaining amount thereof, a first modulator to individually modulate the first light, a first detector to output a first signal based on the first light reflected by the element and the second light passing through the element, a second detector to output a second signal based on the first light passing through the element and the second light reflected by the element, an optical system configured such that the first light and the second light overlap in pairs on the first and second detectors, and a processing unit configured to output information about mode-dependent loss of the target object based on the first signal, the second signal, and information about modulation given by the first modulator.

A test instrument can be coupled to a test point in a passive optical network to measure optical signals transmitted between an optical line terminal and an optical network unit in the optical network. The test instrument can capture an identifier of the ONU from downstream signals sent from the OLT to the ONU.

A method of tuning a production module using a reference module with virtual gain correction is provided. The method includes selecting a counterpart reference module created for a select application. The production module is commutatively coupled to the selected counterpart reference module to generate a production module pair. A production module gain curve for the production module pair is measured for each frequency band to be used by the production module. The production module is tuned based at least in part on offset gain values at select number of frequency observation points for each frequency band associated with the counterpart reference module and gain values at the select number of frequency observation points of the measured production module gain curve for each frequency band.

A method and structure are provided for testing photonic circuits with integrated optical mixers having idle ports. A test port is provided for coupling test light into one or more idle ports of the mixer. Light exiting output ports of the mixer may be measured with photodetectors. Phase errors of optical hybrids may be determined by using waveguides of different lengths to inject test light into two input ports of the mixer and scanning the test wavelength. The method and structure may be used for on-wafer and off-wafer measurements of integrated photonic circuits implementing coherent optical receivers.

There is provided a transmission apparatus including a transmitter configured to modulate a signal to a first signal having a first wavelength and a signal to a second signal having a second wavelength, and transmit the first signal and the second signal to a transmission line so that the second signal is varied in accordance with variation in an amount of cross phase modulation of the first signal passing through each position on the transmission line, and a signal processor configured to include at least one of a logic device and a processor, and configured to add an amount of chromatic dispersion at which a remaining amount of chromatic dispersion of the first wavelength at a certain position on the transmission line is equal to zero to the first wavelength in the transmission of the first signal and the second signal.

The output profile of light from a multimode optical fiber is determined using a geometrical optics approach where the rays launched into the fiber conform to LP-modes of the fiber. This output profile can then be employed as an input to a second fiber to calculate the transmission losses of a coupler that introduces various coupling inaccuracies, such as lateral offset, axial offset, and angular offset.

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