An optical fiber characteristic measurement apparatus (1) includes: a light source (11) configured to output a laser beam of which frequency is modulated; an incident part (12, 13, 14, and 15) configured to make the laser beam output from the light source be incident from one end and another end of an optical fiber (FUT) as continuous light (L1) and pulsed light (L2), respectively; a light detector (16) configured to detect light projected from the optical fiber and output a detection signal (D1); and a detector (17 and 18a) configured to detect, in a first period (T1) in which scattering light based on the continuous light and the pulsed light is projected from the optical fiber and a second period (T2) shorter than the first period, in which the scattering light is not projected from the optical fiber, the scattering light based on integrated values acquired by integrating the detection signal for a predetermined time.

According to examples, a fiber-optic testing source for testing a multi-fiber cable may include a laser source communicatively coupled to a plurality of optical fibers connected to a connector. The fiber-optic testing source may include at least one photodiode communicatively coupled to at least one of the plurality of optical fibers by at least one corresponding splitter to implement a communication channel between the fiber-optic testing source and a fiber-optic testing receiver. The communication channel may be operable independently from a polarity associated with the multi-fiber cable. The fiber-optic testing receiver may include a plurality of photodiodes communicatively coupled to a plurality of optical fibers. The fiber-optic testing receiver may include at least one laser source communicatively coupled to at least one of the plurality of optical fibers by at least one corresponding splitter to implement the communication channel between the fiber-optic testing receiver and a fiber-optic testing source.

According to examples, a fiber-optic testing source for testing a multi-fiber cable may include a laser source communicatively coupled to a plurality of optical fibers connected to a connector. The fiber-optic testing source may include at least one photodiode communicatively coupled to at least one of the plurality of optical fibers by at least one corresponding splitter to implement a communication channel between the fiber-optic testing source and a fiber-optic testing receiver. The communication channel may be operable independently from a polarity associated with the multi-fiber cable. The fiber-optic testing receiver may include a plurality of photodiodes communicatively coupled to a plurality of optical fibers. The fiber-optic testing receiver may include at least one laser source communicatively coupled to at least one of the plurality of optical fibers by at least one corresponding splitter to implement the communication channel between the fiber-optic testing receiver and a fiber-optic testing source.

The present disclosure is directed to systems and methods for calculating a modal time delay and a modal bandwidth. For example, a method may include: transmitting an intensity-modulated light through a mode conditioner to generate a mode-conditioned intensity-modulated light; transmitting the mode-conditioned intensity-modulated light through an optical fiber under test (FUT) to excite a plurality of modes of the optical FUT; converting the mode-conditioned intensity-modulated light transmitted through the optical FUT into an electrical signal; measuring, based on the electrical signal, a transfer function or a complex transfer function of the optical FUT based on at least on one pair of the plurality of modes; calculating a modal delay time of the optical FUT based on the transfer function or the complex transfer function; and calculating a modal bandwidth of the optical FUT based on the modal delay time, the modal bandwidth being calculated for any given launch conditions of the plurality of modes.

According to examples, a fiber-optic testing source for testing a multi-fiber cable may include a laser source communicatively coupled to a plurality of optical fibers connected to a connector. The fiber-optic testing source may include at least one photodiode communicatively coupled to at least one of the plurality of optical fibers by at least one corresponding splitter to implement a communication channel between the fiber-optic testing source and a fiber-optic testing receiver. The communication channel may be operable independently from a polarity associated with the multi-fiber cable. The fiber-optic testing receiver may include a plurality of photodiodes communicatively coupled to a plurality of optical fibers. The fiber-optic testing receiver may include at least one laser source communicatively coupled to at least one of the plurality of optical fibers by at least one corresponding splitter to implement the communication channel between the fiber-optic testing receiver and a fiber-optic testing source.

A test instrument tests an optical component of a fiber optic network. The test instrument determines signal parameters describing pulses to be emitted by lasers of the test instrument to test the optical component, and directly modulates the lasers to repeatedly emit the pulses at different wavelengths on a single fiber optic cable in a time division multiplexing manner. The test instrument triggers powering measurements to coincide with the emitted pulses, and determines performance parameters of the optical component based on the triggered power measurements.

The present disclosure is directed to systems and methods for calculating a modal time delay and a modal bandwidth. For example, a method may include: transmitting an intensity-modulated light through a mode conditioner to generate a mode-conditioned intensity-modulated light; transmitting the mode-conditioned intensity-modulated light through an optical fiber under test (FUT) to excite a plurality of modes of the optical FUT; converting the mode-conditioned intensity-modulated light transmitted through the optical FUT into an electrical signal; measuring, based on the electrical signal, a transfer function or a complex transfer function of the optical FUT based on at least on one pair of the plurality of modes; calculating a modal delay time of the optical FUT based on the transfer function or the complex transfer function; and calculating a modal bandwidth of the optical FUT based on the modal delay time, the modal bandwidth being calculated for any given launch conditions of the plurality of modes.

A test instrument tests an optical component of a fiber optic network. The test instrument determines signal parameters describing pulses to be emitted by lasers of the test instrument to test the optical component, and directly modulates the lasers to repeatedly emit the pulses at different wavelengths on a single fiber optic cable in a time division multiplexing manner. The test instrument triggers powering measurements to coincide with the emitted pulses, and determines performance parameters of the optical component based on the triggered power measurements.

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 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.