Coherent light generators – Particular active media – Semiconductor
Patent
1992-12-24
1994-02-08
Epps, Georgia Y.
Coherent light generators
Particular active media
Semiconductor
372 6, 372 70, 372 69, 385 45, 385 49, H01S 319, H01S 325
Patent
active
052854655
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention is based on a semiconductor lasers, and in particular, to a semiconductor laser having a branched cavity.
2. Background Information
Such a semiconductor laser is disclosed in Electronics Letters, Feb. 15, 1990, Vol. 26, No. 4, pages 243-244. It is monolithically integrated on an n-doped indium phosphide substrate. The underside of the substrate is called the base surface. Above a plane that is coplanar with the base surface, there extends a cavity of indium gallium arsenide phosphide (InGaAsP). It is branched and, when seen from the top, has the shape of a "Y". The top view surface of the cavity may also have a different shape, for example the shape of a cross. Significant is that the cavity is contiguous. This can be described in the sense of a topological definition in that the top view surface of the cavity can be considered to be a "singly contiguous region" since it is not composed of several pieces, but of a single piece having a single edge. The cavity lies on the planar surface of an n-doped buffer layer of indium phosphide that extends above the indium phosphide substrate.
Further layers are provided above the cavity. Above the buffer layer, these layers and the cavity form a mesa which has been produced by etching. In the plane that is coplanar with the base surface, the mesa as well as the cavity have a Y shape.
Such a laser with a branched cavity is provided according to the above-mentioned publication as an electrically controllable light source for optical communications transmission systems. In particular, if its metal layer extending above the cavity is subdivided into several electrodes so that cavity regions are created which can be controlled by means of different operating currents, such a laser is distinguished by its emission wavelength being tunable over a very wide wavelength range. This characteristic is of major importance for the intended use as an electrically controllable light source.
SUMMARY OF THE INVENTION
It is the object of the invention to provide an optical device including such a laser wherein the laser is employed to perform a different function than that of an electrically controllable light source. It is another object of the invention to provide methods of using the novel optical device. This is accomplished by providing a light source with adjustable optical power from which light can be radiated into the laser cavity thus controlling operation of the laser optionally.
Modifications of the optical device are disclosed and described in more detail in the following detailed description of the preferred embodiments.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will now be described in greater detail with reference to the embodiments thereof that are illustrated in the drawings in which:
FIG. 1 depicts a first embodiment of the optical device according to the invention;
FIG. 2 depicts the wavelength of the light emitted by the semiconductor laser 1 of FIG. 1 as a function of the optical power P.sub.E of the light radiated into it;
FIG. 3a depicts the optical power P.sub.E as a function of time for a noise corrupted light signal radiated into the semiconductor laser 1 of FIG. 1;
FIG. 3b depicts the wavelength of the output light signal of the first semiconductor laser as a function of time if a light signal of FIG. 3a is radiated in;
FIG. 3c depicts the time curve for the optical power P.sub.A of the output light signal of the semiconductor laser after it passes through a wavelength selective optical filter if a light signal according to FIG. 3a is radiated in;
FIG. 4a depicts the optical power P.sub.E as a function of time for a light signal radiated into the semiconductor laser and containing a constant light component;
FIG. 4b depicts the time curve for the optical power P.sub.A of the output light signal of the first semiconductor laser after passing through a wavelength selective optical filter if a light signal according to FIG. 4a is radiated in;
FIG. 5 depicts a second embodiment of t
REFERENCES:
patent: 4065729 (1977-12-01), Gover et al.
patent: 5105433 (1992-04-01), Eisele et al.
Proceedings of the 16th European Conference on Optical Communication, Sep. 16-20, 1990; Bd. 1, Amsterdam, NL; pp. 479-482; W. Idler et al.: "High speed integrated . . . ".
IEEE Journal of Quantum Electronics, Bd. 24, Nr. 11, Nov. 1988, NY-US; pp. 2153-2159; H. Kawaguchi et al.: "Tunable optical-wavelength . . . ".
IEEE Transactions Photonics Technology Letters, Bd. 3, Nr. 12, Dec. 1991, NY-US; pp. 1054-1057; M. Schilling et al.: "Multifunctional photonic switching . . . ".
Electronics Letters, Feb. 15, 1990, vol. 24, No. 4, pp. 243, 244; "Widely tunable Y-Coupled . . . ".
Appl. Phys. Lett. 52(10), Mar. 7, 1988; J. Salzman et al.: "Cross coupled cavity . . . ".
Appl. Phys. Lett. 39(10), Nov. 15, 1981; W. T. Tsang: "Extremely low threshold . . . ".
S. M. Sze: "Physics of Semiconductor . . . "; New York, 1981, Chichester, Brisbane, Toronto.
Baums Dieter
Hildebrand Olaf
Idler Wilfried
Laube Gert
Schilling Michael
Alcatel N.V.
Epps Georgia Y.
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