Telefonaktiebolaget Lm Ericsson (publ)

Wei-Ping Huang

Francesco Testa

Kjell Ahlstedt

Tomas Adeback

Luca Giorgi

Ernesto Ciaramella

Antonio D'Errico

Marco Presi

Gemma Vall-Llosera

Ellef Hersoug

David Wallin

Stephane Lessard

Wenxin Zheng

Peter Lindskog

Mats Johansson

Christian Gottlicher Palafox

Lars Wiik

Jan Magnusson

Tomas Adebäck

Systems and methods for controlling optical powers of optical channels in an optical communications network comprising a plurality of nodes is described herein. The method comprises obtaining a reference optical power. The method also includes determining an optical power of an optical channel generated by an optical transmitter of a node. The method further includes applying an attenuation to the optical channel to reduce the optical power of the optical channel to the reference optical power. In some implementations, the method is performed by a network controller operating in the optical communications network.

Optical transceiver and method of controlling optical powers of optical channels

In an optical transceiver, an optical transmitter coupled to a reconfigurable optical channel-add apparatus has first and second add paths, an add micro-ring resonator, and first and second optical attenuators, reconfigurable to selectively block an optical channel from an optical transmitter in one of the first and second add paths. The add micro-ring resonator is reconfigurable selectively to add an optical channel from the first add path to an optical waveguide to travel towards the first add-drop port or to add an optical channel from the second add path to the optical waveguide to travel towards the second add-drop port. An optical receiver is coupled to a reconfigurable optical channel-drop apparatus having a drop micro-ring resonator, and first and second drop paths. The drop micro-ring resonator is reconfigurable selectively to drop an optical channel travelling from the first add-drop port from the optical waveguide to the first drop path or to drop an optical channel travelling from the second add-drop port from the optical waveguide to the second drop path.

An optical source comprises a first laser arranged to generate a first optical signal having a first state of polarization (SOP) and a first optical frequency; a second laser arranged to generate a second optical signal having a second SOP, substantially orthogonal to the first SOP, and having a second optical frequency, different from the first optical frequency by a preselected frequency difference; a polarisation beam coupler arranged to combine the first optical signal and the second optical signal into a composite optical signal comprising both the first optical signal and the second optical signal having said substantially orthogonal SOPs; and an output arranged to output the composite optical signal.

Optical source, communications network optical apparatus and method of providing an optical signal

An optical source () comprising: a first laser () arranged to generate a first optical signal () having a first state of polarization and a first optical frequency; a second laser () arranged to generate a second optical signal () having a second state of polarization, substantially orthogonal to the first state of polarization, and having a second optical frequency, different to the first optical frequency by a preselected frequency difference, &#x394;&#x3bd;; a polarization beam coupler () arranged to combine the first optical signal and the second optical signal into a composite optical signal comprising both the first optical signal and the second optical signal having said substantially orthogonal states of polarization; and an output () arranged to output the composite optical signal ().

A silicon photonic device () comprising: a silicon core () having a core refractive index; and a structure formed in the silicon core, comprising: a first refractive index variation pattern () across the core in a first direction (x) and having a first modulation depth (H); and a second refractive index variation pattern () across the core in a second, orthogonal, direction (y) and having a second modulation depth (H), less than the first modulation depth. The first refractive index variation pattern overlays the second refractive index variation pattern, forming a three-dimensional structure. The first refractive index variation pattern only supports propagation of light having a TM mode between the first direction and a third direction (z) and the second refractive index variation pattern only supports propagation of light having a TE mode between the second direction and the third direction. An optical waveguide coupler is also disclosed. The optical waveguide coupler comprises a plurality of planar waveguides, each supporting propagation of one of a TE and a TM mode, and a plurality of silicon diffractive gratings each comprising a planar silicon core and a grating structure formed by a periodic refractive index variation extending across the core in a first direction and having a grating period and a modulation depth, these selected to cause the grating to support propagation of the light between the first direction and a third direction substantially orthogonal to the planar silicon core. Additionally the optical waveguide coupler comprises a plurality of tapered planar waveguides.

Silicon photonic device, optical polarisation beam coupler and optical waveguide coupler

In aligning ends of optical fibers, e.g. for performing a prealignment of ends of large mode area double-clad fibers (LMA-DCFs) in order to thereafter perform a core alignment process, in a fiber optic fusion splicer a best, optimum or near optimum position or setting of the optical system for observing the self-focusing effect is first determined and then the very alignment operation may be performed using the determined setting. The very alignment process may then be performed by adjusting stepwise the offset distance between the observed fiber ends by e.g. using a cascade technique.

Cladding alignment for fusion splicing optical fibers

A system and method for implementation of a process that propagates a link status across a media converter system implemented in a telecom and/or data com network is provided. More specifically, the system comprise XAUI and PMA/PMD interfaces that support both a copper cable and the different types of SFP+/SFP fiber-optic pluggable modules for accessing a host system and a remote link partner, respectively. With the method, the link statuses at both the copper and fiber-optic link sides of the media converter system are being monitored, such that a change of link status at one side of the media converter system will automatically be propagated across the media converter system to the other side, by dynamically enabling or disabling a respective XAUI or PMD transmitter at the opposite side of a physical layer device (PHY) of the media converter system.

Method and arrangement for enabling link status propagation

A method handling a pluggable module selectable from a plurality of pluggable modules is executable at a media converter system of a network configuration. The method provides for automatically enabling of a disabled channel or disabling of an enabled channel of the media converter system when the pluggable module is attached to the media converter system, wherein the suggested channel enabling/disabling feature is executed on the basis of a correlation between module specific information extracted from the respective pluggable module and corresponding information extracted via the media converter system. An arrangement for executing the suggested method is also provided.

Method and arrangement handling pluggable modules and operating modes in a media converter system

In aligning ends of optical fibers, e.g. ends of large mode area double-clad fibers (LMA-DCFs), in a fiber optic fusion splicer the best position of the object plane of the optical system for observing images of the cores of the fiber ends are first determined by maximizing the contrast of the core image, in particular the core image peak in intensity profiles. The alignment process may be performed by adjusting the offset distance between the observed cores in some suitable way, e.g. by using a cascade technique. In e.g. a process for prealigning the fiber ends the self-focusing effect of optical fibers can be used to first determine the best object plane position for observing the self-focusing effect and then the very pre-alignment operation can be performed. This may extend the range of image analysis allowing e.g. that alignment, in particular core alignment, can be performed without requiring direct information showing the position of sides or edges of the claddings in captured pictures.

Automatic core-alignment for fusion splicing double-clad fibers

In aligning ends of optical fibers (), e.g. for performing a prealignment of ends of large mode area double-clad fibers (LMA-DCFs) in order to thereafter perform a core alignment process, in a fiber optic fusion splicer a best, optimum or near optimum position or setting of the optical system () for observing the self-focusing effect is first determined and then the very alignment operation may be performed using the determined setting. The very alignment process may then be performed by adjusting stepwise the offset distance between the observed fiber ends by e.g. using a cascade technique.

In splicing two optical fibers to each other using an electric arc formed between electrodes images of the regions being heated and thereby fusioned to each other are taken. The images cover a rectangular field () having the fibers located centrally, along a center line of the field and parallel to the long sides of the field. The images are evaluated to determine a value of the position of the center of the electric arc in relation to the position of the end surfaces of the fibers. This value can then be used for placing the end surfaces just at the arc center. In the image the image of the optical fibers can be excluded so that only light intensity from the air discharge of the electric arc is recorded in the captured images. The field () excluded can be a narrow strip of uniform width located symmetrically around the image of the fibers. Using such a repositioning of the end surfaces of the fibers results in splices which are substantially equal to each other and thus a well repeatable splicing process is obtained.

Method of splicing optical fibers with arc imagining and recentering

In positioning or aligning ends of optical fibers in relation to each other an offset distance between the fiber ends, the offset distance e.g. being the distance between predetermined reference positions in the fiber ends, is stepwise adjusted using a cascade technique. The method can be executed accurately and fast and be used e.g. in a procedure for core alignment, the predetermined reference positions then being the positions of the cores of the fiber ends such as the positions of the center lines or axes of the cores. Also, the method can be used in a procedure in which the self-focusing effect of optical fibers is used for finding the reference positions, which in this case are the positions of the center lines or axes of the total fiber ends, i.e. center lines or axes of the surfaces of the claddings of the optical fiber ends. Finally, the method can be used for the longitudinal positioning of the fiber ends in which the gap between end surfaces of the fiber ends is set to a desired value.

Positioning optical fibers

The present invention relates to a method for accurately calibrating fusion temperature in optical fiber splicing. With assistance of direct arc-recentering technique, two optical fibers are spliced and then continuously heated with a post-fusion process. In the process, the fusion temperature is automatically determined in terms of effective fusion currents, which is done by real-time monitoring the fusion time dependence of cladding diameter reduction. In comparison with model calculations, variations of fusion temperature caused by changes of electrode condition and operating environment, e.g. altitude, temperature and humidity are derived. To recover the optimal fusion temperature in various fusion processes, the calibrating results are automatically invoked to compensate fusion currents.

Fusion temperature calibration

When an optical fiber (') is heated by an electrical discharge generated between electrodes () thermal light emission from the core and cladding of fiber forms a hot image which can be observed by an optical imaging system (). Since the concentration of dopants in the core is significantly higher than in the cladding, the light emitted from the core gives a peak structure in the light intensity profile of a hot image. The peak width of the core image increases significantly when dopants diffuse out of the core such as in heating the fiber. The increase of peak width is found to be highly correlated to the expansion of the mode field diameter (MFD) of fiber. This correlation can be experimentally determined at well-defined fusion conditions for any given type of fiber and thereby used to give a measure of the MFD by observing the peak width in hot images. Measures of MFD can be used for improving the quality of estimation of losses in splices of optical fibers.

Determining MFD of optical fibers

Optical fibers (') are fusion spliced to each other by using a CO2 laser () having an emission wavelength of 9.3 microm. The heat absorption of the fibers is higher and the variation of the absorption for small deviations of the wavelength is smaller than at the conventional wavelength of 10.6 microm. As a result, less laser power is needed, the laser construction may be more compact and safety problems can easier be handled. The optical arrangement for the light beam of the CO2 laser includes deflecting and focusing the collimated laser beam () emitted by the laser using a mirror () having a curved surface of concave nearly paraboloid shape, the splice position () located at a small distance of the focus of the mirror and well outside the collimated beam.

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Stockholm, Sweden

Wei-Ping Huang