Systems and methods include, responsive for a requirement to calibrate a single span in a multi-span optical line system where the single span includes a from-end node and a to-end node, determining no other upstream node in the multi-span optical multiplex section is currently calibrating or faulted; responsive to no other upstream node currently calibrating or faulted, calibrating the from-end node with a new target launch power into a fiber associated with the single span; and calibrating the to-end node keeping target launch power into a fiber associated with an immediate downstream span from the single span uninterrupted from a previous calibration. The to-end node and the from-end node are each (1) an intermediate line amplifier or (2) a terminal node and an intermediate line amplifier, in the multi-span optical line system.

Systems and methods for avoiding fiber damage of an optical fiber link are provided. A method, according to one implementation, includes monitoring optical signals transmitted along an optical fiber link from an output port of a first card to an input port of a second card. In response to detecting a fiber disconnection state when an amplifier of the first card is operating in a normal condition, the amplifier of the first card enters a forced Automatic Power Reduction (APR) condition. In addition to potentially reducing the risk of eye damage from laser light emitted from the optical fiber link, the forced APR condition is configured to allow for an uninterrupted debugging procedure. Also, the method includes returning the amplifier of the first card from the forced APR condition back to the normal operating condition after receiving an indication that the fiber disconnection state has cleared.

A single-ended data transmission system transmits a signal having a signal voltage that is referenced to a power supply voltage and that swings above and below the power supply voltage. The power supply voltage is coupled to a power supply rail that also serves as a signal return path. The signal voltage is derived from two signal supply voltages generated by a pair of charge pumps that draw substantially same amount of current from a power supply.

Embodiments of the invention include methods and devices for determining a phase angle offset between a phase angle of a local oscillator relative to a phase angle of a signal input of a Device Under Test (DUT). Some embodiments include a laser source and an optical phase adjustor, which may be embodied by a loop stretcher structured to controllably stretch a length of fiber optic cable, driven by a phase adjust driver. In other embodiments the phase angle offset information is conveyed to an oscilloscope for internal compensation.

A submarine optical repeater includes a submarine amplifier module, which further includes a pumping laser module and an optical detector module. The pumping laser module generates optical amplifications within an optical cable, and, in the case of a fault in the optical cable, the optical detector module detects at least one characteristic of an optical signal caused by the fault in the optical cable. This configuration then identifies a particular signal characteristic that indicates a fault within the optical cable.

Disclosed is a method of characterizing a multimode optical fiber link including a light source and two or more multimode fibers. The method includes a step of characterizing each of said multimode fibers using a measurement of the Dispersion Modal Delay (DMD) for each of said multimode fibers, and delivering, for each of said multimode fibers, at least three fiber characteristic curves as a function of a radial offset value r; a step of characterizing the light source by at least three source characteristic curves showing at least three parameters of the source as a function of a fiber radius r and obtained by a technique similar to the DMD measurement; and a step of computing an Effective Bandwidth (EB) of the link, comprising calculating a transfer function using both each of said source characteristic curves and each of said at least three fiber characteristic curves for each of said multimode fibers.

In an optical fiber monitoring system which detects physical disturbance or other parameters such as temperature or strain of a fiber where a monitor signal is transmitted along the optical fiber and analyzed to detect changes which are indicative of an event, a method is provided for periodically checking proper operation of the optical fiber monitoring system. A fiber disturbance actuator periodically causes a pattern of disturbances of a portion of the fiber at a predetermined location thereon where the disturbance is characteristic of the event to be monitored. The monitor signal is analyzed to detect the pattern of changes and in the event that expected changes are not detected, a warning is issued that the intrusion detection system is not properly operating.

Techniques are disclosed for aligning an optical transmitter with an optical receiver for a line-of-sight communications link, wherein the optical transmitter comprises a laser array emitter, the laser array emitter comprising a plurality of laser emitting regions, wherein each of a plurality of the laser emitting regions is configured to emit laser light in a different direction such that the laser array emitter is capable of emitting laser light in a plurality of different directions. The system can run produce emissions from different laser emitting regions until a laser emitting region that is in alignment with the optical receiver is found. This aligned laser emitting region can then be selected for use to optically communicate data from the optical transmitter to the optical receiver.

A hybrid automated testing equipment (ATE) system can simultaneously test electrical and optical components of a device under test, such as an optical transceiver. The device under test can be a multilane optical transceiver that transmits different channels of data on different lanes. The hybrid ATE system can include one or more light sources and optical switches in an optical test lane selector to selectively test and calibrate each optical and electrical components of each lane of the device under test.

Embodiments of the present invention generally relate to the field of fiber optics, and more specifically to apparatuses, methods, and/or systems associated with testing fiber optic transmitters. In an embodiment, the present invention is an apparatus comprising a laser optimized multimode fiber having near minimally compliant effective modal bandwidth, near maximum channel length, and α-profile that produces an R-MMF DMD slope.