Optical waveguides – Integrated optical circuit
Reexamination Certificate
2003-01-09
2004-11-23
Palmer, Phan T. H. (Department: 2874)
Optical waveguides
Integrated optical circuit
C385S003000, C385S008000, C372S050121, C359S248000
Reexamination Certificate
active
06823095
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
The invention pertains to an optoelectronic component having at least one monolithically integrated laser diode and at least one monolithically integrated optical waveguide.
Electro-optical data transmission with high data transmission rates (e.g. >10 Gbit/s) requires a fast intensity control of the light sources. Since the intensity control is not possible using laser diodes alone, electro-optical modulators (e.g. electro-absorption modulators) are used. The voltage changes for driving the modulators cannot be provided by silicon-based controllers (drivers), particularly not at high data transmission rates. Moreover, a high signal level with a high contrast or a high extinction ratio is necessary for reliable data transmission.
These different requirements are taken into account only incompletely by the prior art.
In order to reduce the required voltage changes during the driving, it has become known, in principle, to use a tandem structure of electroabsorption modulators (F. Alexandre, et al. “Butt-coupled waveguide-modulators by low temperature embedded CBE regrowth for high speed modulation (43 GHz) for large extinction ratio (>50 dB), Proc. InP and Rel. Material, 1997 Intern. Conference, May 11-15, 1997, pp. 621-24). However, this tandem structure has only been realized in principle as an experimental construction, and not for providing a monolithically integrated optoelectronic device.
SUMMARY OF THE INVENTION
It is accordingly an object of the invention to provide an optoelectronic component, which overcomes the above-mentioned disadvantages of the heretofore-known devices and methods of this general type and which provides for an active electro-optical device that can be driven efficiently.
With the foregoing and other objects in view there is provided, in accordance with the invention, an optoelectronic component, comprising:
at least one monolithically integrated laser diode;
a plurality of electro-optical modulators, preferably electro-absorption modulators;
at least one monolithically integrated optical waveguide functionally coupled to at least two of the electro-optical modulators; and
at least one optical amplifier assigned to at least one of the electro-optical modulators.
The functional coupling of an optical waveguide to at least two electro-optical modulators, in particular electroabsorption modulators, makes it possible for the electroabsorption modulators to be made relatively short. This has the advantage that the capacitances of the electroabsorption modulators are negligible in comparison with the capacitances of possible leads (e.g. traveling wave contacts). It is thus possible to separate the dimensioning and the arrangement of the electrical waveguides and of the optical waveguides from one another. In this case, at least one electroabsorption modulator is assigned at least one optical amplifier since losses in the electroabsorption modulator can thus be compensated for.
In this case, it is advantageous if at least two electro-absorption modulators are arranged along the optical waveguide.
In order to compensate for losses, it is also advantageous if at least one optical amplifier is arranged between two electroabsorption modulators and/or an optical amplifier is arranged at the end of the optical waveguide.
In an advantageous refinement of the invention, at least one of the electroabsorption modulators is connected to an electronic control circuit via a traveling wave contact.
It is particularly advantageous if the length of the electroabsorption modulators is equal to or shorter than the length of the optical amplifiers. Short electroabsorption modulators have the effect that the capacitance becomes smaller than that of the leads, so that a decoupling of electrical and optical lines is possible.
In this case, it is advantageous if at least one electroabsorption modulator has a length of less than 150 &mgr;m.
In an advantageous manner, at least one optical waveguide and at least one electrical waveguide are arranged on different substrates.
It is advantageous that the monolithically integrated components,,in particular electroabsorption modulators, optical amplifiers and/or laser diodes have the material systems InGaAsP/InP, InGaAlAs/InP, InGaAsN/GaAs or InGaAlAs/GaAs. These systems are well suited in particular to operation at high frequencies.
It is advantageous that the monolithically integrated components, in particular electroabsorption modulators, optical amplifiers and/or laser diodes, are functionally coupled via a common active layer.
In an advantageous manner, the active layer has multiple quantum well structures of different quantum well types, which can thus be set to the respective operating conditions. Quantum dot structures can also advantageously be used. For more information concerning quantum well and quantum dot structures and other related information, see my copending, concurrently filed application Nos. 10/339,243, 10/339,242 and 10/339,232 [Atty. dockets M&N-IT-410, M&N-IT-412, and M&N-IT-413], the disclosures of which are herewith incorporated by reference.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in an optoelectronic device, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.
REFERENCES:
patent: 5680411 (1997-10-01), Ramdane et al.
patent: 5811838 (1998-09-01), Inomoto
patent: 6574260 (2003-06-01), Salvatore et al.
patent: 196 00 194 (1996-11-01), None
patent: 196 24 514 (1997-07-01), None
Alexandre, F. et al.: “Butt-Coupled Waveguide-Modulators by Low Temperature Embedded CBE Regrowth for High Speed Modulation (42GHz) or Large Extinction Ratio (50dB)”, IEEE, 1997, pp. 621-624.
Ramdane, A. et al.: “Monolithic Integration of Multiple-Quantum-Well Lasers and Modulators for High-Speed Transmission”, IEEE Journal of Selected Topics in Quantum Electronics, vol. 2, No. 2, Jun. 1996, pp. 326-335.
Greenberg Laurence A.
Infineon - Technologies AG
Mayback Gregory L.
Palmer Phan T. H.
Stemer Werner H.
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