News Column

Researchers Submit Patent Application, "Optical Phase-Sensitive Amplifier for Dual-Polarization Modulation Formats", for Approval

August 7, 2014



By a News Reporter-Staff News Editor at Politics & Government Week -- From Washington, D.C., VerticalNews journalists report that a patent application by the inventors Yang, Jeng-Yuan (Garland, TX); Sekiya, Motoyoshi (Richardson, TX); Akasaka, Yoichi (Allen, TX), filed on January 14, 2013, was made available online on July 24, 2014.

The patent's assignee is Fujitsu Limited.

News editors obtained the following quote from the background information supplied by the inventors: "Telecommunications systems, cable television systems and data communication networks may use optical networks to rapidly convey large amounts of information between remote points. In an optical network, information may be conveyed in the form of optical signals through optical fibers. Optical fibers may comprise thin strands of glass capable of communicating the signals over long distances with very low loss. Optical networks often employ modulation schemes to convey information in the optical signals over the optical fibers. Such modulation schemes may include phase-shift keying ('PSK'), frequency-shift keying ('FSK'), amplitude-shift keying ('ASK'), and quadrature amplitude modulation ('QAM').

"In PSK, the information carried by the optical signal may be conveyed by modulating the phase of a reference signal, also known as a carrier wave. The information may be conveyed by modulating the phase of the signal itself using differential phase-shift keying ('DPSK').

"In QAM, the information carried by the optical signal may be conveyed by modulating both the amplitude and phase of the carrier wave. PSK may be considered a subset of QAM, wherein the amplitude of the carrier waves is maintained as a constant.

"PSK and QAM signals may be represented using a complex plane with real and imaginary axes on a constellation diagram. The points on the constellation diagram representing symbols carrying information may be positioned with uniform angular spacing around the origin of the diagram. The number of symbols to be modulated using PSK and QAM may be increased and thus increase the information that can be carried. The number of signals may be given in multiples of two. As additional symbols are added, they may be arranged in uniform fashion around the origin. PSK signals may include such an arrangement in a circle on the constellation diagram, meaning that PSK signals have constant power for all symbols. QAM signals may have the same angular arrangement as that of PSK signals, but include different amplitude arrangements. QAM signals may have their symbols arranged around multiple circles, meaning that the QAM signals include different power for different symbols. This arrangement may decrease the risk of noise as the symbols are separated by as much distance as possible. A number of symbols 'm' may thus be used and denoted 'm-PSK' or 'm-QAM.'

"Examples of PSK and QAM with a different number of symbols can include binary PSK ('BPSK' or '2-PSK') using two phases at 0.degree. and 180.degree. (or 0 and .pi.) on the constellation diagram; or quadrature PSK ('QPSK', '4-PSK', or '4-QAM') using four phases at 0.degree., 90.degree., 180.degree., and 270.degree. (or 0, .pi./2, .pi., and 3.pi./2). Phases in such signals may be offset. Each of 2-PSK and 4-PSK signals may be arranged on the constellation diagram.

"M-PSK signals may also be polarized using techniques such as dual-polarization QPSK ('DP-QPSK'), wherein separate m-PSK signals are multiplexed by orthogonally polarizing the signals. M-QAM signals may also be polarized using techniques such as dual-polarization 16-QAM ('DP-16-QAM'), wherein separate m-QAM signals are multiplexed by orthogonally polarizing the signals."

As a supplement to the background information on this patent application, VerticalNews correspondents also obtained the inventors' summary information for this patent application: "In one embodiment, a method for amplifying optical signals includes determining a source optical signal, generating a first resultant signal including a pump signal and the source optical signal, sending the first resultant signal through a non-linear element to generate a second resultant signal including the first resultant signal and an idler signal, and sending the second resultant signal through a non-linear element to perform phase-sensitive amplification. The phase-sensitive amplification results in a third resultant signal including an amplified source optical signal. The method also includes filtering the third resultant signal to remove the pump signal and the idler signal and outputting the amplified source optical signal.

"In another embodiment, a system for amplifying optical signals includes an input configured to accept a source optical signal, a pump source configured to generate a pump signal, a coupler configured to add the pump signal to the source optical signal to yield a first resultant signal, a first controller, a second controller, and a filter. The first controller is configured to split the first resultant signal into an x-polarization component and a y-polarization component and send the x-polarization component of the first resultant signal and the y-polarization component of the first resultant signal bi-directionally through a first non-linear element to generate an x-polarization component and a y-polarization component of a second resultant signal including the first resultant signal and an idler signal. The second controller is configured to send the x-polarization component of the second resultant signal and the y-polarization component of the second resultant signal bi-directionally through a second non-linear element to perform phase-sensitive amplification. The phase-sensitive amplification results in a third resultant signal including an amplified source optical signal. The filter is configured to filter the third resultant signal and output the amplified source optical signal.

"In yet another embodiment, a system for amplifying optical signals includes an input configured to accept a source optical signal, a pump source configured to generate a pump signal, a coupler configured to add the pump signal to the source optical signal to yield a first resultant signal, a controller, and a filter. The controller is configured to split the first resultant signal into an x-polarization component and a y-polarization component, and route the x-polarization component of the first resultant signal bi-directionally through a first non-linear element to yield an x-polarization component of a second resultant signal. The first non-linear element is configured to perform phase-sensitive amplification on the x-polarization component of the first resultant signal. The controller is also configured to route the y-polarization component of the first resultant signal bi-directionally through a second non-linear element to yield a y-polarization component of the second resultant signal. The second non-linear element is configured to perform phase-sensitive amplification on the y-polarization component of the first resultant signal. The controller is also configured to combine the x-polarization component of the second resultant signal and the y-polarization component of the second resultant signal to yield the second resultant signal. The filter is configured to filter the second resultant signal and output an amplified source optical signal.

"In still yet another embodiment, a system for amplifying optical signals includes an input configured to accept a source optical signal, a pump source configured to generate a pump signal, a coupler configured to add the pump signal to the source optical signal to yield a first resultant signal, a polarization-maintaining non-linear element communicatively coupled to the coupler, and a filter and configured to filter an amplified signal and output an amplified source optical signal. The polarization-maintaining non-linear element is configured to add an idler signal to the first resultant signal as the first resultant signal passes through the polarization-maintaining non-linear element in a first direction that yields a second resultant signal, sends the second resultant signal to be rerouted to the polarization-maintaining non-linear element, receives the second resultant signal, and performs phase-sensitive amplification on the second resultant signal as the second resultant signal passes through the polarization-maintaining non-linear element in a second direction, yielding the amplified signal. The first direction and second direction are opposites.

BRIEF DESCRIPTION OF THE DRAWINGS

"For a more complete understanding of the present invention and its features and advantages, reference is now made to the following description, taken in conjunction with the accompanying drawings, in which:

"FIG. 1 illustrates an example embodiment of a system configured to provide optical phase-sensitive amplification for dual-polarization modulation formats;

"FIG. 2 is an illustration of an example embodiment of a system with an optical amplifier for conducting optical phase-sensitive amplification;

"FIGS. 3A and 3B are an illustration of the operation of an example embodiment of an optical amplifier for conducting optical phase-sensitive amplification on a single channel;

"FIGS. 4A and 4B are an illustration of the operation of an example embodiment of an optical amplifier for conducting optical phase-sensitive amplification on wavelength division multiplexing (WDM) channels;

"FIG. 5 is an illustration of an another example embodiment of system with an optical amplifier for conducting optical phase-sensitive amplification;

"FIG. 6 is an illustration of the operation of another example embodiment of an optical amplifier for conducting optical phase-sensitive amplification on a single channel;

"FIG. 7 is an illustration of the operation of another example embodiment of an optical amplifier for conducting optical phase-sensitive amplification on WDM channels;

"FIG. 8 is an illustration of a yet another example embodiment of an optical amplifier for conducting optical phase-sensitive amplification;

"FIG. 9 is an illustration of the operation of yet another example embodiment of an optical amplifier for conducting optical phase-sensitive amplification on a single channel;

"FIG. 10 is an illustration of the operation of yet another example embodiment of an optical amplifier for conducting optical phase-sensitive amplification on WDM channels; and

"FIG. 11 is an example embodiment of a method for optical phase-sensitive amplification."

For additional information on this patent application, see: Yang, Jeng-Yuan; Sekiya, Motoyoshi; Akasaka, Yoichi. Optical Phase-Sensitive Amplifier for Dual-Polarization Modulation Formats. Filed January 14, 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=3503&p=71&f=G&l=50&d=PG01&S1=20140717.PD.&OS=PD/20140717&RS=PD/20140717

Keywords for this news article include: Fujitsu Limited, Fiber Optic Network.

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: Politics & Government Week


Story Tools






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