An optical fiber test apparatus includes an optical power meter operable to detect light at a predetermined wavelength, and a laser source operable to generate a visible laser beam. The optical fiber test apparatus further includes an optical connector comprising a test port, and an optical fiber extending between a first end and a second end and coupled at the second end to the optical connector. The optical fiber test apparatus further includes a coupling device, the coupling device coupled to the optical power meter, the laser source, and the first end of the optical fiber. The coupling device is operable to transmit light at the predetermined wavelength from the optical connector to the optical power meter and transmit the visible laser beam from the laser source to the optical connector.

Using pump-probe measurements on multi-span optical links may result in the determination of one or more of the following: 1) wavelength-dependent power profile and gain evolution along the optical link; 2) wavelength-dependent dispersion map; and 3) location of regions of high polarization-dependent loss (PDL) and polarization-mode dispersion (PMD). Such measurements may be a useful diagnostic for maintenance and upgrade activities on deployed cables as well as for commissioning new cables.

The invention introduces a new RF test and measurement methodology based on optical signal processing that has the capability to measure all of the RF parameters (both amplitude and phase) of an electronic component or system including transmission (S.sub.21) and reflection (S.sub.11). It can also be applied to measuring the electro-optic properties of electro-optic modulators, both phase modulators and intensity modulators. The basis of the invention is to use the RF information encoded in the optical sidebands generated by an electro-optic modulator to determine all of the relevant parameters of an electronic or electro-optic device. Optical carrier suppression techniques are used to isolate the information carrying optical sidebands from the dominant optical carrier.

An optical fiber characteristics measurement apparatus (10) according to the present disclosure measures the characteristics of an optical fiber. The optical fiber characteristics measurement apparatus (10) includes a laser light source module (11) that outputs frequency-modulated laser light. The laser light source module (11) includes a laser light source (110) that outputs laser light, a laser light source driver (111) that modulates the frequency of the laser light outputted by the laser light source (110), and an optical amplifier (116) that adjusts the amplitude of the frequency-modulated laser light outputted by the laser light source (110) so as to cancel an amplitude modulation occurring in the frequency-modulated laser light outputted by the laser light source (110).

In some examples, dual-end loopback-based multi-fiber cable measurement may include connecting at least two multi-fiber loopback devices respectively to a near end and a far end of a multi-fiber cable to place at least two fibers of the multi-fiber cable in series. The at least two multi-fiber loopback devices may include a near-end multi-fiber loopback device connected to a fiber optic reflectometer and to the near end of the multi-fiber cable to connect together at least two near-end fibers of the multi-fiber cable. Further, the at least two multi-fiber loopback devices may include a far-end multi-fiber loopback device connected to the far end of the multi-fiber cable to connect together at least two far-end fibers of the multi-fiber cable.

A measuring method of a longitudinal distribution of bending loss of an optical fiber includes calculating an arithmetical mean value I(x) from two backscattering light intensities of two backscattering light at a position x obtained by bidirectional OTDR measurement of the optical fiber; and obtaining a bending loss value at the position x from a mode field diameter 2W(x) and a relative refractive index difference (x) at the position x calculated from the arithmetical mean value.

An apparatus and a method for transmission of optical signals. The apparatus includes a bidirectional amplification device communicatively coupled between a first communication terminal and a second communication terminal. The first and second communication terminals are communicatively coupled using an optical communication link. The bidirectional amplification device is configured to transmit and amplify one or more optical sensing signals transmitted in either direction between the first communication terminal and the second communication terminal. The optical sensing signals indicate a status of one or more portions of the optical communication link.