News Column

Patent Issued for Opto-Electronic Assembly for a Line Card

August 6, 2014

By a News Reporter-Staff News Editor at Electronics Newsweekly -- A patent by the inventor Earnshaw, Mark P. (Morristown, NJ), filed on November 12, 2010, was published online on July 22, 2014, according to news reporting originating from Alexandria, Virginia, by VerticalNews correspondents.

Patent number 8787775 is assigned to Alcatel Lucent (Paris, FR).

The following quote was obtained by the news editors from the background information supplied by the inventors: "The present invention relates to optical communication equipment and, more specifically but not exclusively, to line cards.

"This section introduces aspects that may help facilitate a better understanding of the invention(s). Accordingly, the statements of this section are to be read in this light and are not to be understood as admissions about what is in the prior art or what is not in the prior art.

"An optical line card is used for interfacing optical communication lines, e.g., carrying optical signals to and from the subscribers, to the rest of the telecommunications access network. A typical optical line card is a modular opto-electronic circuit assembled on a printed circuit board. Its representative modules may include an optical transmitter, an optical receiver, an optical add/drop multiplexer, a digital signal processor, a controller, a power-management unit, a performance monitor, various optical and electrical interfaces, etc.

"Different modules of an optical line card may be implemented using monolithic integration. A monolithic integrated circuit is usually fabricated on a single piece of semiconductor substrate, e.g., by (i) incorporating dopants into the substrate, (ii) depositing and patterning additional layers of material, and (iii) metallizing and packaging the resulting chip."

In addition to the background information obtained for this patent, VerticalNews journalists also obtained the inventor's summary information for this patent: "A hybrid integrated circuit is a multi-component circuit constructed of multiple monolithic integrated circuits. For example, one circuit may include semiconductor and optical devices, and the other circuit may include one or more passive components, with both monolithic circuits being arranged over the same mechanical sub-mount. In the prior art, neither monolithic nor hybrid integration has allowed straightforward production of both the passive optical elements and the electro-optical elements of an optical transmitter or receiver.

"Disclosed herein are various embodiments of an opto-electronic assembly that can be used in an optical receiver of a line card. In one embodiment, the opto-electronic assembly is a hybrid integrated circuit having an array of avalanche photodiodes (APDs) that are electrically coupled to a corresponding array of transimpedance amplifiers (TIAs), with both the APDs and TIAs being mounted on a common ceramic substrate. The opto-electronic assembly further has an optical subassembly comprising an arrayed waveguide grating (AWG) and an array of turning mirrors, both attached to a temperature-control unit in a side-by-side arrangement and flip-chip mounted on the substrate over the APDs. The opto-electronic assembly employs a silicon-based submount inserted between the APDs and the substrate to accommodate the height difference between the APDs and the TIAs. The submount advantageously enables the placement of APDs in relatively close proximity to the turning mirrors while providing good control of the APD's tilt and offset distance with respect to the substrate. The temperature-control unit enables independent temperature control of the AWG and of the array of turning mirrors, which helps to achieve good optical-coupling efficiency between the AWG and the APDs even when the turning mirrors have a relatively small size.

"According to another embodiment, provided is an apparatus comprising: a support structure having a planar surface; a first planar substrate located at an offset distance from the planar surface and having a first optical device, the first optical device having an array of first optical ports along an edge of the first planar substrate; a second planar substrate located at an offset distance from the planar surface and having one or more second optical devices with second optical ports along a second edge of the second planar substrate, the second edge facing the first edge; a first heater thermally coupled to the first planar substrate; and a second heater thermally coupled to the second planar substrate. The first planar substrate has a substantially different thermal expansivity than the second planar substrate. The first heater and the second heater are configured to be separately controllable.

"According to yet another embodiment, provided is an apparatus having a support plate, a plurality of photo-detectors mounted on the support plate, a plurality of amplifiers mounted on the support plate and electrically connected to receive electrical signals generated by the photo-detectors in response to received light, and an optical subassembly mounted on the support plate. The photo-detectors are positioned between the optical sub-assembly and the support plate. The optical subassembly is configured to direct light to the photo-detectors."

URL and more information on this patent, see: Earnshaw, Mark P.. Opto-Electronic Assembly for a Line Card. U.S. Patent Number 8787775, filed November 12, 2010, and published online on July 22, 2014. Patent URL:

Keywords for this news article include: Electronics, Semiconductor, Alcatel Lucent.

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Source: Electronics Newsweekly

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