Methods, systems, and apparatus, for an external cavity FP laser. In one aspect, an apparatus is provided that includes a FP laser diode; a Faraday rotator (FR) coupled to receive an optical output of the FP laser diode and that rotates a polarization of the optical output; an optical fiber coupled at a first end to receive the output of the FR; a WDM filter coupled to a second end of the optical fiber to receive the optical signal from the optical fiber; and a FRM coupled directly or indirectly to an output of the WDM filter, wherein an optical output of the WDM filter is partially reflected by the FRM such that the polarization of a reflected beam is rotated, and wherein the reflected optical signal then passes through the FR with its polarization being rotated by the FR before it is injected back into the FP laser diode.

Methods and apparatuses are provided to modify existing overlay system architectures in a cost effective manner to meet the growing demand for narrowcast services and to position the existing overlay systems for additional future modifications. The implementations of the improved overlay system of this disclosure re-digitize narrowcast analog signals after they have been QAM modulated and upconverted to RF frequencies and replace the analog narrowcast transmitters with digital narrowcast transmitters. In the fiber nodes, the received narrowcast signals are converted back to analog signals and combined with analog broadcast signals for transmission to the service groups.

The present disclosure discloses a method and an apparatus for implementing registration. The method includes: tuning, by optical network units (ONUs), own reception wavelengths to a downlink wavelength corresponding to any one of time-wavelength division multiplexing (TWDM) channels; and receiving, from optical line terminals (OLTs) by the ONUs, downlink frames containing operator information, judging that the operator information in the received downlink frames is same as operator information preconfigured in the ONUs, searching for an uplink wavelength corresponding to a current received wavelength in a corresponding relationship between the uplink wavelength and the downlink wavelength received from the OLTs, and tuning own uplink wavelengths to the searched uplink wavelength for registration.

A station-side device of the present invention includes: a wavelength change instruction unit that issues, to a subscriber-side device, a wavelength change instruction to change a transfer-source wavelength assigned to the subscriber-side device to a transfer-target wavelength different from the transfer-source wavelength; a transfer-source port that transmits and receives an optical signal of the transfer-source wavelength; a transfer-target port that transmits and receives an optical signal of the transfer-target wavelength; a transfer-source port monitoring unit that detects a connection between the transfer-source port and the subscriber-side device; a transfer-target port monitoring unit that detects a connection between the transfer-target port and the subscriber-side device; a transfer-source timer that counts, at the transfer-source port, an elapsed time from a predetermined starting time in response to the wavelength change instruction, and ends the counting of the elapsed time in a case where change to the transfer-target wavelength is complete; and a transfer-target timer that counts, at the transfer-target port, an elapsed time from a predetermined time in response to the wavelength change instruction, and ends the counting of the elapsed time in a case where the change to the transfer-target wavelength is complete.

In a case where a wavelength to be assigned to a subscriber-side device, to which a downstream wavelength has been assigned, is to be changed from the currently used (Source) downstream wavelength to a different changeover target (Target) downstream wavelength, a downstream wavelength changeover instruction message that indicates the change target wavelength is generated. In a case where a wavelength to be assigned to the subscriber-side device, to which an upstream wavelength has been assigned, is to be changed from the currently used (Source) upstream wavelength to a different changeover target (Target) upstream wavelength, an upstream wavelength changeover instruction message that indicates the change target wavelength is generated. The downstream wavelength changeover instruction message and the upstream wavelength changeover instruction message are respectively independently generated, and only the wavelength for which the wavelength changeover instruction message was generated is changed.

A telecommunications system may include a measurement receiver to confirm the presence of a MIMO signal prior to decoding signals to avoid decoding spectrum that does not include MIMO signals. The measurement receiver may determine a fast Fourier transform (FFT) spectrum for asynchronous wideband digital signals received from two or more ports. The measurement receiver may determine an average FFT spectrum based on the determined FFT spectrum and identify a bandwidth of signals present in the average FFT spectrum. The measurement receiver may identify the MIMO signals present in the bandwidth of signals and decode only the identified MIMO signals.

A computerized system and method for managing a passive optical network (PON) is disclosed. The system includes a detection and analysis module adapted for receiving uploaded measurement data from an optical line terminal (OLT) and at least one optical network terminal (ONT), and at least one of technical tools data, service failure data, and outside plant data. The detection and analysis module is adapted for determining a source of failure or potential failure in the PON by correlating the uploaded measurement data and the at least one of technical tools data and service failure data with information stored in a memory medium for the OLT and each ONT.

This application provides a wavelength negotiation method of a multi-wavelength passive optical network, including: receiving a wavelength status table that is broadcast by an OLT over each downstream wavelength channel of a multi-wavelength PON system, where the wavelength status table is used to indicate information about available wavelengths of the multi-wavelength PON system and statistic information of registered ONUs of a corresponding wavelength channel; selecting an upstream transmit wavelength and a downstream receive wavelength according to the wavelength status table; and reporting information about the upstream transmit wavelength and information about the downstream receive wavelength to the OLT so that the OLT refreshes the wavelength status table. This application also provides a wavelength negotiation apparatus of the multi-wavelength passive optical network and a multi-wavelength passive optical network system.

Methods and apparatuses are provided to modify existing overlay system architectures in a cost effective manner to meet the growing demand for narrowcast services and to position the existing overlay systems for additional future modifications. The implementations of the improved overlay system of this disclosure re-digitize narrowcast analog signals after they have been QAM modulated and upconverted to RF frequencies and replace the analog narrowcast transmitters with digital narrowcast transmitters. In the fiber nodes, the received narrowcast signals are converted back to analog signals and combined with analog broadcast signals for transmission to the service groups.

An electrochemically active material is represented by general formula (I): Si.sub.uSn.sub.vM.sub.1wM.sub.2x[P.sub.0.2O.sub.0.8].sub.y.A.sub.z(I) where u, v, w, x, y, and z represent atomic % values and u+v+w+x+y+z=100, M.sub.1 includes a metal element or combinations of metal elements selected from Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zr, B, carbon, or alloys thereof, M.sub.2 includes a metal element or combinations of metal elements selected from Mg, Al, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Zr, or alloys thereof, A is an inactive phase other than a phosphate or silicide, and 0<u<90, 0v<20, 0<w<50, 0<x<20, 0<y<20, and 0z<50.