Optical semiconductor component with a deep ridged waveguide

Details Optical semiconductor component with a deep ridged waveguide Optical semiconductor component with a deep ridged waveguide

1998-09-01

2001-01-30

Sanghavi, Hemang (Department: 2874)

Coherent light generators

Particular active media

Semiconductor

C372S046012, C372S050121, C385S131000

Reexamination Certificate

active

06181722

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Technical Field
The invention concerns an optical semiconductor component as claimed in patent claim
1
.
2. Discussion of Related Art
Optical semiconductor components are used in digital optical telecommunications e.g. as transmitting or receiving components, and are coupled to optical waveguides on a supporting plate, or to optical fibers. Optical semiconductor components with a deep ridged waveguide are especially used for the highest bit frequencies in telecommunications, since they have the highest frequency bandwidth due to their low electrical capacity, as is compared to optical semiconductor components with other types of waveguides.
A deep ridged waveguide is an optical waveguide formed of a mesa-shaped ridge on a substrate, and the ridge contains waveguide layers having a higher refraction index than the substrate. Especially in actively operated, i.e. controlled light absorbing or amplifying deep ridged waveguides, the ridge contains optically active semiconductor layers, and thereby a zone containing the transition from p-doped to n-doped semiconductor material. The ridge which is several Am wide is laterally surrounded by material that is electrically nonconducting and has a clearly smaller refraction index, such as e.g. air or polyimide.
In contrast thereto, a flat ridged waveguide represents an optical waveguide in which at least a part of the existing waveguide layers are arranged under a mesa-shaped ridge which is several &mgr;m wide. Particularly in actively operated flat ridged waveguides, the optically active semiconductor layers are not part of the ridge, thus the zone containing the transition from p-doped to n-doped semiconductor material is not laterally limited to the several Am wide ridge.
In order to couple a light wave being conducted in an optical semiconductor component as much as possible without loss into an optical waveguide or an optical fiber, it is necessary to adapt the mode field of the light wave in the semiconductor component to the mode field of a light wave in the optical waveguide or in the optical fiber. To that end the mode field of the light wave being conducted in the semiconductor component is adiabatically amplified along the light propagation direction.
To adapt the mode field, the optical semiconductor components use waveguides containing a transition area in which the waveguide, or individual layers of the waveguide, taper or widen laterally along a longitudinal direction of the waveguide, meaning the direction in the substrate plane that is vertical to the light propagation direction, or vertically, meaning the direction that is vertical to the substrate plane. Such a transition area is also called a taper. A vertical taper particularly defines a transition area in which the thickness of a semiconductor layer increases or decreases, and a lateral taper defines a transition area in which the width of a waveguide increases or decreases along a longitudinal direction.
The article “Compact InGaAsP/InP laser diodes with integrated mode expander for efficient coupling to flat-ended single-mode fibre” (T. Brenner et al, Electronic Letters, Volume 31, No. 7 1995, pages 1443-1445) describes an optical semiconductor component with a flat ridged waveguide. It contains an optically active waveguide layer and a ridge arranged on this waveguide layer. The thickness of the optically active waveguide layer decreases in a transition area along a longitudinal direction of the ridged waveguide in the direction of an outlet facet of the component, and the ridged waveguide widens laterally in the direction of the outlet facet. The ridged waveguide and the transition area are equipped with electrodes, and are actively operated by applying a voltage.
The described semiconductor component has a higher capacity than semiconductor components with deeply etched ridged waveguides, particularly in the actively operated transition area. In addition, in a ridged waveguide in which the mode field adaptation takes place mainly through an actively operated lateral taper, higher modes than the basic mode are excited, so that such a waveguide loses its single modality.
SUMMARY OF THE INVENTION
The object of the invention is to present an optical semiconductor component that is suitable for the highest transmission rates, and can be coupled in a mostly loss-free manner to an optical fiber or to an optical waveguide.
According to the present invention, an optical semiconductor component which has a substrate and a deep ridged waveguide with a cover layer arranged on the substrate is characterized in that the ridged waveguide contains a first waveguide core and a second waveguide core, whose respective refractive indexes are greater than refractive indexes of the cover layer and the substrate, the first waveguide core contains one or several optically active semiconductor layers, and in a first transition area, a thickness of the second waveguide core decreases along a longitudinal direction of the deep ridged waveguide.
In further accord with the present invention, the optical semiconductor component is characterized further in that it has a front face for incoming or outgoing light signals, and the thickness of the second waveguide core decreases along the longitudinal direction of the ridged waveguide toward the front facet.
In still further accord with the present invention, the optical semiconductor component is further characterized in that the decrease in a layer thickness of the second waveguide core is continuous.
Further in accordance with the present invention, the optical semiconductor component is further characterized in that the one or several optically active semiconductor layers of the first waveguide core are a semiconductor packet with a multi-quantum well structure.
Still further in accord with the present invention, the optical semiconductor component is further characterized in that in a second transition area, thickness of individual layers of the semiconductor packet of the first waveguide core decreases in a same direction along which the thickness of the second waveguide core decreases in said longitudinal direction.
In further accord with the present invention, the optical semiconductor component is further characterized in that in a third transition area, a width of the ridged waveguide increases in a same direction along which the thickness of the second waveguide core decreases in said longitudinal direction.
According still further to the present invention, the optical semiconductor component is further characterized in that on the front face, the ridged waveguide has a termination in the form of an integrated cylindrical lens with a hyperbolic, parabolic or circle segment shaped base.


REFERENCES:
patent: 5933562 (1999-08-01), Dutting et al.
patent: 5937120 (1999-08-01), Higashi
patent: 5987046 (1999-11-01), Kobayashi et al.
patent: 6037189 (2000-03-01), Goto
patent: 6052397 (2000-04-01), Jeon et al.
patent: 0641049 (1995-03-01), None
patent: 9800894 (1998-01-01), None
“Ultrahigh-bandwidth (42GHz) polarisation-independent ridge wageguide electroabsorption modulator based on tensile strained InGaAsP MQW”, K. Satzke et al,Electronics Letters, Nov. 9, 1995, vol. 31, No. 23, pp. 2030-2032.
“Compact InGaAsP/InP laser diodes with integrated mode expander for efficient coupling to flat-ended singlemode fibres”, T. Brenner et al,Electronics Letters, Aug. 17, 1995, vol. 31, No. 17, pp. 1443-1445.
“Monolithic Integration of AgInAsP/InP Collimating GRIN Lens with Tapered Waveguide Active Region”, S. El Yumin et al, Proc. International Conf. on Indium Phosphide and Related Materials, Hokkido, May 9-13, 1997, pp. 721-724.
“Theoretische Untersuchung optischer Wellenleitertaper auf InGaAsP/InP”, H-P. Nolting et al,Frequenz, vol. 45, No. 5/06, May 1, 1991, pp. 130-140.

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