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Researchers Submit Patent Application, "Optical Semiconductor Element, Method of Controlling the Same and Method of Manufacturing the Same", for...

July 30, 2014



Researchers Submit Patent Application, "Optical Semiconductor Element, Method of Controlling the Same and Method of Manufacturing the Same", for Approval

By a News Reporter-Staff News Editor at Electronics Newsweekly -- From Washington, D.C., VerticalNews journalists report that a patent application by the inventor Akiyama, Tomoyuki (Yokohama, JP), filed on March 12, 2014, was made available online on July 17, 2014.

The patent's assignee is Fujitsu Limited.

News editors obtained the following quote from the background information supplied by the inventors: "Practical application of optical devices using silicon as a material of an optical waveguide is important to enable small sizing, large capacity, and low power consumption of optical transmitting and receiving devices. This is because an optical waveguide whose refractive index difference is large can be used, and therefore, it is advantageous for small sizing compared to other materials. Besides, integration with an electronic circuit is easy, and therefore, it is possible to integrate a number of optical transmitting and receiving devices on one chip. Particularly, characteristics of a modulator among optical devices largely affect on the power consumption and size of optical transmitting and receiving devices. In particular, a ring modulator among modulators is advantageous to enable the small sizing and the low power consumption because an element in itself is small, a modulation voltage is small, and an optical loss thereof is small.

"However, in a ring modulator, a wavelength band and a modulation efficiency are in a relationship of tradeoff. Accordingly, when high modulation efficiency is to be obtained, the wavelength band is narrow, and it is difficult to match a wavelength of an incident light such as a CW (continuous wave) light and a resonant wavelength. Arts objecting to solve the above-stated problems have been proposed, but it is difficult to enable a stable control.

"Patent Literature 1: U.S. Patent Application Laid-open No. 2009/0169149

"Patent Literature 2: Japanese Laid-open Patent Publication No. 2009-200091"

As a supplement to the background information on this patent application, VerticalNews correspondents also obtained the inventor's summary information for this patent application: "According to an aspect of the embodiments, an optical semiconductor element includes: a ring modulator; and a light absorbing material provided at a position apart from a path for a modulated light which is guided by the ring modulator, the light absorbing material absorbing a light leaked out of a ring waveguide of the ring modulator, and increasing a temperature of the ring waveguide.

"According to another aspect of the embodiments, a method of controlling an optical semiconductor element includes; heating an optical semiconductor element to a particular temperature or more with a heater, the optical semiconductor element including: a ring modulator; and a light absorbing material provided at a position apart from a path for a modulated light which is guided by the ring modulator, the light absorbing material absorbing a light leaked out of a ring waveguide of the ring modulator, and increasing a temperature of the ring waveguide; starting incidence of a modulated light to the ring modulator; and after the starting, stopping the heating with the heater. A heating value in a first relationship is larger than a heating value in a second relationship at a ring resonant wavelength giving a maximum to the first relationship, the first relationship being a relationship between a ring resonant wavelength and a heating value according to absorption of a resonance light in the ring waveguide, and the second relationship being a relationship between a heating value and a ring resonant wavelength which changes according to the heating value in the ring waveguide. The particular temperature is a temperature corresponding to a nearest intersection on a short wavelength side from the ring resonant wavelength giving the maximum to the first relationship among intersections between a graphic chart representing the first relationship and a graphic chart representing the second relationship.

"According to still another aspect of the embodiments, a method of manufacturing an optical semiconductor element includes: forming a ring modulator; and forming a light absorbing material at a position apart from a path for a modulated light which is guided by the ring modulator, the light absorbing material absorbing a light leaked out of a ring waveguide of the ring modulator, and increasing a temperature of the ring waveguide.

"The object and advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the claims.

"It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not restrictive of the invention.

BRIEF DESCRIPTION OF DRAWINGS

"FIG. 1A is a view illustrating an example of a ring modulator;

"FIG. 1B is a view illustrating characteristics of the ring modulator illustrated in FIG. 1A;

"FIG. 2A is a view illustrating another example of a ring modulator;

"FIG. 2B is a view illustrating characteristics of the ring modulator illustrated in FIG. 2A;

"FIG. 3A is a view illustrating still another example of a ring modulator;

"FIG. 3B is a view illustrating characteristics of the ring modulator illustrated in FIG. 3A;

"FIG. 4A is a view illustrating a relationship between a heating value and a ring resonant wavelength in a ring waveguide;

"FIG. 4B is a view illustrating a relationship between a heating value according to absorption of a resonance light and a ring resonant wavelength;

"FIG. 4C is a view in which a graphic chart illustrated in FIG. 4A and a graphic chart illustrated in FIG. 4B are overlaid;

"FIG. 5A is a view illustrating characteristics at an initial stage;

"FIG. 5B is a view illustrating characteristics after heating;

"FIG. 5C is a view illustrating characteristics after heating is stopped;

"FIG. 6 is a view illustrating a relationship between a modulation voltage V and a transmittance;

"FIG. 7A is a view illustrating a relationship between a ring resonant wavelength and a heating value in consideration of modulation;

"FIG. 7B is a view in which a graphic chart illustrated in FIG. 7A and a graphic chart illustrated in FIG. 4B are overlaid;

"FIG. 8 is a view illustrating a relationship between a graphic chart illustrated in FIG. 6 and a locked wavelength;

"FIG. 9 is a view illustrating operations for a burst signal in which a burst-off state and a burst-on state are mixed;

"FIG. 10A is a view illustrating a layout of an optical semiconductor element according to a second embodiment;

"FIG. 10B is a sectional view along a I-II line in FIG. 10A;

"FIG. 10C is a sectional along a III-II line in FIG. 10A;

"FIG. 11A is a view illustrating a layout of an optical semiconductor element according to a third embodiment;

"FIG. 11B is a sectional view along a I-II line in FIG. 11A;

"FIG. 11C is a sectional view along a III-II line in FIG. 11A;

"FIG. 12A is a view illustrating a layout of an optical semiconductor element according to a fourth embodiment;

"FIG. 12B is a sectional view along a I-II line in FIG. 12A;

"FIG. 12C is a sectional view along a III-II line in FIG. 12A;

"FIG. 13A is a view illustrating a layout of an optical semiconductor element according to a fifth embodiment;

"FIG. 13B is a sectional view along a I-II line in FIG. 13A;

"FIG. 13C is a sectional view along a III-II line in FIG. 13A;

"FIG. 14A is a flowchart illustrating an example of a method of controlling an optical semiconductor element according to a sixth embodiment;

"FIG. 14B is a flowchart illustrating another example of a method of controlling an optical semiconductor element according to the sixth embodiment;

"FIG. 15A to FIG. 15P are sectional views illustrating a method of manufacturing an optical semiconductor element according to a seventh embodiment in process sequence.

"FIG. 16A is a view illustrating a structure of an optical semiconductor element according to an eighth embodiment;

"FIG. 16B is a view illustrating operations of the optical semiconductor element according to the eighth embodiment; and

"FIG. 17 is a view illustrating an optical semiconductor element according to a ninth embodiment."

For additional information on this patent application, see: Akiyama, Tomoyuki. Optical Semiconductor Element, Method of Controlling the Same and Method of Manufacturing the Same. Filed March 12, 2014 and posted July 17, 2014. Patent URL: http://appft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&u=%2Fnetahtml%2FPTO%2Fsearch-adv.html&r=3073&p=62&f=G&l=50&d=PG01&S1=20140710.PD.&OS=PD/20140710&RS=PD/20140710

Keywords for this news article include: Electronics, Fujitsu Limited, Semiconductor.

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Source: Electronics Newsweekly


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