An Optical Time Domain Reflectometer (OTDR) module obtains Optical Return Loss (ORL) of a fiber plant. Calibration information is obtained of at least internal OTDR reflections associated with the OTDR module. The OTDR module is connected to the fiber plant. An ORL response is measured due to reflections of an ORL signal transmitted from the OTDR module along the fiber plant, and a peak OTDR response is measured in response to reflections of an OTDR signal transmitted from the OTDR module along the fiber plant. A corrected ORL response of the fiber plant is determined by: using the measured peak OTDR response (e.g., peak value or area under the peak) and the calibration information to calculate the calculated ORL due to internal reflections, and then adjusting the measured ORL response by the calculated ORL to represent the corrected ORL of the fiber plant.

Methods for estimating the Effective Modal Bandwidth (EMB) of laser optimized Multimode Fiber (MMF) at a specified wavelength, λ.sub.S, based on the measured EMB at a first reference measurement wavelength, λ.sub.M. In these methods the Differential Mode Delay (DMD) of a MMF is measured and the Effective Modal Bandwidth (EMB) is computed at a first measurement wavelength. By extracting signal features such as centroids, peak power, pulse widths, and skews, as described in this disclosure, the EMB can be estimated at a second specified wavelength with different degrees of accuracy. The first method estimates the EMB at the second specified wavelength based on measurements at the reference wavelength. The second method predicts if the EMB at the second specified wavelength is equal or greater than a specified bandwidth limit.

Provided are a light transmission device and a control method of same which can switch a processing sequence according to a vendor of an optical module to be mounted thereon. The light transmission device, which is provided with ports on which optical modules which transmit an optical signal are mounted, is additionally provided with: a storage means for holding a table in which processing sequences respectively corresponding to pieces of identification information about the optical modules are stored; and a control means for acquiring pieces of identification information about the mounted optical modules, determining, with reference to the table, a processing sequence corresponding to the identification information about the acquired optical module, and executing the determined processing sequence for the optical module.

A light source unit generates an optical signal out of a bend-insensitive (“BI”) optical fiber that is compliant with a desired encircled flux (“EF”). The unit includes a light source to generate an optical light signal and a conventional multimode optical fiber coupled to receive the optical light signal from the light source at a first end. A modal conditioner is arranged to condition the optical light signal propagating along different modes of the conventional multimode fiber. A first bend-insensitive (BI) multimode optical fiber has an input end, the input end of the first BI multimode optical fiber being coupled at a second end of the conventional multimode optical fiber to receive the conditioned optical light signal from the conventional multimode fiber. The output from the first BI multimode optical fiber outputs an optical signal having the desired EF.

Provided are a light transmission device and a control method of same which can switch a processing sequence according to a vendor of an optical module to be mounted thereon. The light transmission device, which is provided with ports on which optical modules which transmit an optical signal are mounted, is additionally provided with: a storage means for holding a table in which processing sequences respectively corresponding to pieces of identification information about the optical modules are stored; and a control means for acquiring pieces of identification information about the mounted optical modules, determining, with reference to the table, a processing sequence corresponding to the identification information about the acquired optical module, and executing the determined processing sequence for the optical module.

The present disclosure provides a testing method for optical communication module, and a test device. The testing method includes: reading encoded information from the optical communication module to be tested; obtaining a pre-stored optimal test parameter corresponding to the optical communication module, and adjusting test parameter configuration of test device accordingly to the optimal test parameter; obtaining test mode configuration, and performing a test on the optical communication module to obtain first test result; and obtaining a determination result according to the first test result and expected result. This method improves test efficiency and proposes a test device which emulates the estimated common performance characteristics of the main stream networking devices where the optical communication module attaches to in real-life applications, therefore, a qualified module passing the proposed test method has much lower possibility of having the interoperability issue mentioned in the background of the present disclosure.

Methods for estimating the Effective Modal Bandwidth (EMB) of laser optimized Multimode Fiber (MMF) at a specified wavelength, λ.sub.S, based on the measured EMB at a first reference measurement wavelength, λ.sub.M. In these methods the Differential Mode Delay (DMD) of a MMF is measured and the Effective Modal Bandwidth (EMB) is computed at a first measurement wavelength. By extracting signal features such as centroids, peak power, pulse widths, and skews, as described in this disclosure, the EMB can be estimated at a second specified wavelength with different degrees of accuracy. The first method estimates the EMB at the second specified wavelength based on measurements at the reference wavelength. The second method predicts if the EMB at the second specified wavelength is equal or greater than a specified bandwidth limit.

The embodiments of the present disclosure provide an avalanche photo diode (APD) performance detection method and apparatus for an optical module, and an optical network and a medium. The method is applicable to an optical network including an optical module and an optical network unit (ONU); the method includes: selecting at least one optical network unit identifier (ONU ID) as a detection ONU ID; allocating a bandwidth to the detection ONU ID and enabling the bandwidth; acquiring received optical power of the optical module for the detection ONU ID; and determining, on the basis of the received optical power, whether the performance of an APD in the optical module deteriorates.

A process of estimating a transfer function or an inverse transfer function of the optical transmitter from first data obtained by the optical receiver when a first known signal is transmitted from the transmitter to the receiver, and a temporary transfer function or a temporary inverse transfer function of the optical receiver, is performed for multiple frequency offsets between the optical transmitter and the optical receiver. At this time, the transfer function or the inverse transfer function of the optical transmitter is estimated by comparing the first data obtained by compensating at least one or none of a temporary transfer function of the optical receiver and transmission path characteristics detected in the receiver, with a first known signal before transmission to which what is not compensated for the first data between the temporary transfer function of the optical receiver and the transmission path characteristic is added.

Aspects of the present disclosure describe a method for estimating mode field distribution in optical fibers from guided acoustic-wave Brillouin scattering wherein light for which the optical mode-field distribution is determined remains in the optical fibers and the distribution is made for light inside the fiber, and not at a fiber/air interface or other perturbation points to the fiber resulting in a more accurate representation of the optical mode-field distribution in the fiber. Since light is always in the fiber during the determination, no complicated fiber preparation steps or procedures are required and the mode-field distribution is determined as an average distribution along the length of the fiber under test.