News Column

Researchers Submit Patent Application, "Isolated Modulator Electrodes for Low Power Consumption", for Approval

August 6, 2014



By a News Reporter-Staff News Editor at Electronics Newsweekly -- From Washington, D.C., VerticalNews journalists report that a patent application by the inventors MARGALIT, Near (Westlake Village, CA); HEIMBUCH, Mark (Chatsworth, CA); Zhang, Xingang (Chatsworth, CA), filed on January 11, 2013, was made available online on July 24, 2014.

No assignee for this patent application has been made.

News editors obtained the following quote from the background information supplied by the inventors: "Light-emitting devices such as lasers are useful for optical signal generation in optoelectronic networks. Often, light from a laser is modulated to encode data or information onto the signal. One approach to modulating laser light is electro-absorption modulation (EAM), in which an electric potential applied across the modulator either allows light to pass through the modulator or creates a destructive interference pattern in the light passing into the modulator, thereby turning the light signal off.

"To reduce power, the optical signal output by the electro-absorption modulated laser (EML) can be transmitted differentially. Differential modulation using electro-absorption modulators has either used discrete laser and modulator devices, or, if integrated on a single chip, the modulator section and the laser section generally have common electrical contact points. The common electrical contact points typically include the cathode, n-contact, and/or ground. The anodes or p-contacts of the laser section and modulator section are typically electrically isolated.

"However, in a multi-channel transmitter (i.e., having a plurality of paired lasers and modulators), providing a common ground contact for the modulators does not allow for driving each modulator with a differential signal. Differential modulation has typically involved either a shared contact between the modulator section and laser section, or a laser that is not integrated onto the modulator chip.

"This 'Discussion of the Background' section is provided for background information only. The statements in this 'Discussion of the Background' are not an admission that the subject matter disclosed in this 'Discussion of the Background' section constitutes prior art to the present disclosure, and no part of this 'Discussion of the Background' section may be used as an admission that any part of this application, including this 'Discussion of the Background' section, constitutes prior art to the present disclosure."

As a supplement to the background information on this patent application, VerticalNews correspondents also obtained the inventors' summary information for this patent application: "Embodiments of the present invention relate to methods, architectures, circuits, and/or systems for making and/or using electro-modulated lasers (EMLs) having isolated modulator electrodes (e.g., both anodes and cathodes) for use in multi-channel optoelectronic devices. Such isolated electrodes advantageously reduce power consumption and/or increase transmission speeds in such devices. However, such systems, methods, etc. can also be applied to devices other than EMLs (for example, any type of integrated multi-channel system or method having multiple modulators that can benefit from electrical isolation from each other and/or from the signal source[s]). The present optoelectronic devices may be useful for optical communication, optical data storage, and other uses.

"In one embodiment, a light-emitting device (e.g., an electro-modulated laser) can include (a) a substrate, (b) a lower contact layer on or over the substrate, the lower contact layer comprising a first lower contact in a first region of the substrate and a plurality of second lower contacts in a second region of the substrate, a plurality of light-emitting thin film devices on or over the first lower contact in the first region of the substrate, (d) a plurality of light-modulating thin film devices on or over the plurality of second lower contacts in the second region of the substrate, (e) a plurality of first upper contacts on or over the plurality of light-emitting thin film devices, (f) a plurality of second upper contacts on or over the plurality of light-modulating thin film devices, and (g) an isolation region between the first and second regions of the substrate, electrically separating the plurality of first upper contacts and the plurality of second upper contacts.

"In another embodiment, a method of making a multichannel light-emitting device can include (a) forming a lower contact layer on a substrate, (b) patterning the lower contact layer to form a first lower contact in a first region of the substrate and a plurality of second lower contacts in a second region of the substrate, forming a first thin film PN structure on the first lower contact and the plurality of second lower contacts, (d) forming a first upper contact layer on the first thin film PN structure, (e) removing the first thin film PN structure and the first upper contact layer in the second region, (f) forming a second thin film PN structure and a second upper contact layer in the second region, and (g) forming an isolation region between the first and second regions, electrically separating the first upper contact layer and the second upper contact layer. As a result, the method generally forms a plurality of light-emitting devices in the first region and a plurality of light-modulating devices in the second region, and each light-emitting device may be paired with a light-modulating device to form an electro-modulated laser (EML).

"In yet another embodiment, a multi-channel light-emitting device can include (a) a substrate, (b) a lower contact layer on or over the substrate, the lower contact layer comprising a first lower contact in a first region of the light-emitting device and a plurality of second lower contacts in a second region of the light-emitting device, a plurality of laser diodes on or over the first lower contact in the first region, (d) a plurality of modulators on or over the plurality of second lower contacts in the second region, wherein each of the plurality of modulators is configured to modulate light from a corresponding one of the plurality of laser diodes, (e) a plurality of waveguides on or over a third region of the light-emitting device, wherein each of the plurality of waveguides is configured to direct light from a corresponding one of the plurality of modulators towards a target; (f) and a wave combiner configured to receive light from each of the plurality of waveguides.

"By providing separate upper and lower contacts for each modulator, embodiments of the present invention can advantageously provide low-power differential drive capability for an integrated array of EML devices on a single chip or substrate. Embodiments of the present invention also provide an approach in which a plurality of lasers and modulators can be integrated on the same chip or substrate, but also electrically isolated from each other. Differential driving and EA modulation saves power and costs in an optoelectronic transmitter (TX) module. Thus, the present invention enables transceivers to integrate multiple EML devices on one chip or substrate for optical signal transmission, over a single fiber or parallel fibers. These and other advantages of the present invention will become readily apparent from the detailed description of various embodiments below.

BRIEF DESCRIPTION OF THE DRAWINGS

"FIG. 1 shows an exemplary layout for a multi-channel light-emitting device in accordance with embodiments of the present invention.

"FIGS. 2-9 are cross-sectional views showing structures formed in an exemplary method of making the exemplary multi-channel light-emitting device of FIG. 1 in accordance with embodiments of the present invention.

"FIG. 10A shows a cross-sectional view of an exemplary laser diode region of the multi-channel light-emitting device of FIG. 1 along the A-A' axis.

"FIG. 10B shows a cross-sectional view of an exemplary modulator region of the multi-channel light-emitting device of FIG. 1 along the B-B' axis."

For additional information on this patent application, see: MARGALIT, Near; HEIMBUCH, Mark; Zhang, Xingang. Isolated Modulator Electrodes for Low Power Consumption. Filed January 11, 2013 and posted July 24, 2014. Patent URL: http://appft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&u=%2Fnetahtml%2FPTO%2Fsearch-adv.html&r=3062&p=62&f=G&l=50&d=PG01&S1=20140717.PD.&OS=PD/20140717&RS=PD/20140717

Keywords for this news article include: Patents, Laser Diodes, Optoelectronics.

Our reports deliver fact-based news of research and discoveries from around the world. Copyright 2014, NewsRx LLC


For more stories covering the world of technology, please see HispanicBusiness' Tech Channel



Source: Electronics Newsweekly


Story Tools






HispanicBusiness.com Facebook Linkedin Twitter RSS Feed Email Alerts & Newsletters