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| United States Patent |
5,875,274
|
|
Stein
|
February 23, 1999
|
Optoelectronic transmission-reception device
Abstract
An optoelectronic transmission-reception device has a semiconductor laser
and reception diode fashioned monolithically integrated in a semiconductor
chip whose laser resonator is formed by two outer limiting surfaces of the
semiconductor chip arranged opposite one another. The laser light emitted
by the semiconductor laser is incident into a light waveguide coupled to
one limiting surface of the semiconductor chip at the light waveguide
side. The coupling of the light waveguide to the semiconductor laser and
reception diode fashioned monolithically integrated in the semiconductor
chip is fashioned such and the limiting surface of the semiconductor chip
at the light waveguide side is of such a nature that, given an adequately
low reflectivity of the laser emission emitted by the laser that is
required for adequate assurance of the laser function, an optimally large
part of the radiation received via the light waveguide is incident into
the semiconductor laser and reception diode.
| Inventors:
|
Stein; Karl-Ulrich (Unterhaching, DE)
|
| Assignee:
|
Siemens Aktiengesellschaft (Munich, DE)
|
| Appl. No.:
|
716530 |
| Filed:
|
September 19, 1996 |
Foreign Application Priority Data
| Sep 20, 1995[DE] | 195 34 936.9 |
| Current U.S. Class: |
385/49; 372/50; 385/14; 385/37 |
| Intern'l Class: |
G02B 006/30; H01S 003/19 |
| Field of Search: |
385/14,37,49-51,31
372/50,45,46,49
|
References Cited [Referenced By]
U.S. Patent Documents
| 3952265 | Apr., 1976 | Hunsperger | 372/50.
|
| 4045120 | Aug., 1977 | de Corlieu et al.
| |
| 4601535 | Jul., 1986 | Tanaka et al.
| |
| 5031188 | Jul., 1991 | Koch et al. | 372/45.
|
| 5392308 | Feb., 1995 | Welch et al. | 372/50.
|
| 5392372 | Feb., 1995 | Kurata et al.
| |
| 5617439 | Apr., 1997 | Kakimoto | 385/49.
|
| Foreign Patent Documents |
| 0 495 559 A1 | Jul., 1992 | EP.
| |
| 44 04 756 A1 | Aug., 1995 | DE.
| |
| WO 88/05970 | Nov., 1988 | WO.
| |
| WO 94/11930 | May., 1994 | WO.
| |
Other References
Patent Abstract of Japan, vol. 10, No. 264, (P-495), dated 09 Sep. 1986 &
JP-A-61-090108 dated 08 May 1986.
|
Primary Examiner: Sanghavi; Hemang
Attorney, Agent or Firm: Hill & Simpson
Claims
What is claimed is:
1. An optoelectronic transmission-reception device, comprising:
semiconductor laser and reception diode monolithically integrated in a
semiconductor chip;
the semiconductor chip having first and second outer limiting surfaces
arranged opposite one another, the surfaces forming a laser resonator for
the semiconductor laser;
a light waveguide coupled to the first limiting surface of the
semiconductor chip at a light waveguide side, laser light emitted by the
semiconductor laser being incident into the light waveguide;
a coupling of the light waveguide to the semiconductor laser and reception
diode being structured, and the first limiting surface of the
semiconductor chip at the light waveguide side having a configuration such
that, given a low reflectivity of the laser emission emitted by the laser
that is required for assurance of the laser function, an optimally large
part of the radiation received via the light waveguide is incident into
the semiconductor laser and reception diode; and
a field transformer for adapting an optical light output field from spatial
dimensions of a light exit face of the laser to an entry face of the
coupled light waveguide, the field transformer being between a
light-emitting end of the semiconductor laser and the first limiting
surface of the semiconductor chip facing toward the end of the light
waveguide.
2. The optoelectronic transmission-reception device according to claim 1,
wherein the first limiting surface of the semiconductor chip at the light
waveguide side has a substantially non-reflective surface or,
respectively, a surface having substantially complete optical
transmissivity for radiation received via the light waveguide.
3. The optoelectronic transmission-reception device according to claim 1
wherein the coupling of the light waveguide to the first limiting surface
of the semiconductor chip at the light waveguide side has a thin matching
layer applied to a surface of the first limiting surface of the
semiconductor chip at the light waveguide side that faces toward the light
waveguide, said matching layer being of such a nature or, respectively,
having such a material that an optimally large part of the radiation
received via the light waveguide is incident into the semiconductor laser
and reception diode.
4. The optoelectronic transmission-reception device according to claim 3,
wherein the material of the thin matching layer applied to that surface of
the first limiting surface of the semiconductor chip at the light
waveguide side that faces toward the light waveguide has a refractive
index of at least approximately a geometrical average of values of a
refractive index of the semiconductor laser and reception diode and of a
refractive index of the material of the light waveguide.
5. The optoelectronic transmission-reception device according to claim 4
wherein the refractive index of the material of the matching layer has a
value from about 1.5 to about 3.0 given a refractive index of the
semiconductor chip material of about 3.3 to about 3.8 and a reflective
index of the material of the light waveguide of about 1.4 to about 1.6.
6. The optoelectronic transmission-reception device according to claim 3,
wherein the material of the matching layer has a low optical absorption
coefficient.
7. The optoelectronic transmission-reception device according to claim 1
wherein a surface of the first limiting surface of the semiconductor laser
facing away from the light waveguide is highly reflective for the laser
light.
8. The optoelectronic transmission-reception device according to claim 1,
wherein the device further comprises a monitor diode for control of output
power of the semiconductor laser, the monitor diode being integrated on
the semiconductor chip.
9. The optoelectronic transmission-reception device according to claim 1,
wherein the semiconductor laser and reception diode fashioned
monolithically integrated in the semiconductor chip has a laser with a DFB
or a DBR arrangement with a Bragg grating.
10. The optoelectronic transmission-reception device according to claim 1,
wherein the semiconductor laser and reception diode fashioned
monolithically integrated in the semiconductor chip operates with light of
a first wavelength in a transmission mode and operates with light of a
second wavelength in the reception mode, the second wavelength being
different from the first wavelength.
11. The optoelectronic transmission-reception device according to claim 10,
wherein the first wavelength and the second wavelength lie in close
proximity to one another.
12. The optoelectronic transmission-reception device according to claim 10
wherein the device further comprises a grating reflector that is
integrated in the semiconductor chip for separating the two lights with
the first and second wavelengths.
13. The optoelectronic transmission-reception device according to claim 10,
wherein in a reception mode, the light of the second wavelength passes the
grating reflectors at both sides of the laser diode required for
substantially unattenuated laser operation.
14. The optoelectronic transmission-reception device according to claim 10,
wherein the device further comprises a reflector arrangement that has a
high reflectivity for the light of the second wavelength, the reflector
arrangement being at an end of the semiconductor laser.
15. The optoelectronic transmission-reception device according to claim 1,
wherein the material of the semiconductor chip is a III-V semiconductor.
16. The optoelectronic transmission-reception device according to claim 1,
wherein the material of the semiconductor chip is InGaAsP on an InP
substrate.
17. An optoelectronic transmission-reception device, comprising:
semiconductor laser and reception diode monolithically integrated in a
semiconductor chip;
the semiconductor chip having first and second outer limiting surfaces
arranged opposite one another, the surfaces forming a laser resonator for
the semiconductor laser;
a light waveguide coupled to the first limiting surface of the
semiconductor chip at a light waveguide side, laser light emitted by the
semiconductor laser being incident into the light waveguide;
a coupling of the light waveguide to the semiconductor laser and reception
diode being structured, and the first limiting surface of the
semiconductor chip at the light waveguide side having a configuration such
that, given a low reflectivity of the laser emission emitted by the laser
that is required for assurance of the laser function, an optimally large
part of the radiation received via the light waveguide is incident into
the semiconductor laser and reception diode;
the coupling of the light waveguide to the first limiting surface of the
semiconductor chip having a thin matching layer applied to a surface of
the first limiting surface of the semiconductor chip at the light
waveguide side that faces toward the light waveguide; and
a field transformer for adapting an optical light output field from spatial
dimensions of a light exit face of the laser to an entry face of the
coupled light waveguide, the field transformer being between a
light-emitting end of the semiconductor laser and the first limiting
surface of the semiconductor chip facing toward the end of the light
waveguide, the field transformer being structured to substantially limit
dissipated power of the laser emission.
18. The optoelectronic transmission-reception device according to claim 17,
wherein a material of the thin matching layer applied to that surface of
the first limiting surface of the semiconductor chip at the light
waveguide side that faces toward the light waveguide has a refractive
index of approximately a geometrical average of values of a refractive
index of the semiconductor laser and reception diode and of a refractive
index of the material of the light waveguide, and wherein a surface of the
first limiting surface of the semiconductor laser facing away from the
light waveguide is highly reflective for the laser light.
19. An optoelectronic transmission-reception device, comprising:
semiconductor laser and reception diode monolithically integrated in a
semiconductor chip;
the semiconductor chip having first and second outer limiting surfaces
arranged opposite one another, the surfaces forming a laser resonator for
the semiconductor laser;
a light waveguide coupled to the first limiting surface of the
semiconductor chip at a light waveguide side, laser light emitted by the
semiconductor laser being incident into the light waveguide;
a coupling of the light waveguide to the semiconductor laser and reception
diode being structured, and the first limiting surface of the
semiconductor chip at the light waveguide side having a configuration such
that, given a low reflectivity of the laser emission emitted by the laser
that is required for assurance of the laser function, an optimally large
part of the radiation received via the light waveguide is incident into
the semiconductor laser and reception diode;
the semiconductor laser and reception diode having a transmission mode and
a reception mode, light having a first wavelength being used in the
transmission mode and light having a second wavelength being used in the
reception mode, the first wavelength and the second wavelength being in
close proximity to one another and being different from one another; and
a field transformer for adapting an optical light output field from spatial
dimensions of a light exit face of the laser to an entry face of the
coupled light waveguide, the field transformer being between a
light-emitting end of the semiconductor laser and the first limiting
surface of the semiconductor chip facing toward the end of the light
waveguide, the field transformer being structured to substantially limit
dissipated power of the laser emission.
Description
BACKGROUND OF THE INVENTION
The present invention is directed to an optoelectronic
transmission-reception device that, in particular, can be utilized as
transmission-reception transducer for half-duplex operation.
Since the medium of optical fiber (light waveguide) has largely replaced
the copper cable in the long-distance network and trunk line network in
communications transmission technology, the introduction of optical fiber
technology in the subscriber circuit domain is an important task in coming
years. The subscriber circuit domain represents the most cost-intensive
domain of the telecommunication networks. This fact leads to efforts on
the part of the network operators to find a solution that is cost-neutral
and future-proof compared to the copper line. Different design
possibilities for a transmission architecture in the subscriber circuit
domain are being currently investigated. In one architecture considered to
possibly have good prospects, the transmission between a terminal
equipment at the exchange side (OLT=optical line termination) and a
plurality of network termination at the subscriber side (ONU=optical
network unit) ensues in the form of a star network with passive
distribution that, given a realizable subscriber line length of about 10
km, represents an advantageous concentration of the number of subscribers
at a switching center. In this design possibility for a
point-to-multipoint connection, the optical fiber can be conducted up to
the home of the subscriber in a preferred distribution structure (FTTH,
fiber to the home, i.e. the network termination ONU of the subscriber side
is located in the home). What is referred to as the TDM/TDMA method (time
division multiplexing/time division multiple access), for example, is a
suitable transmission method given such an architecture. A time-division
multiplex frame is transmitted to all ONUs in the direction to the
subscriber (downstream) (TDM). The individual ONUs then access their
channels in the completely received frame. In the direction from the
subscriber (upstream), the individual ONUs transmit their data bursts to
the OLT in a predetermined sequence (TDMA).
Half-duplex operation wherein transmission or, respectively, reception is
carried out in chronological succession at one end of the light waveguide
is advantageous for data rates into the range of 150 and more megabits per
second. Optoelectronic transmission-reception transducers for operation at
the end of a light waveguide are still in an early stage of employment.
Their costs, however, are of critical significance for the spread of the
concept of fiber to the home (FTTH). Particularly for data rates in the
indicated range, half-duplex operation or, respectively, what is referred
to as ping-pong operation wherein transmission or, respectively, reception
is carried out in chronological succession at one end possibly allows a
more cost-beneficial structure of the transmission-reception module than
given full-duplex operation.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an optoelectronic
transmission-reception device available for half-duplex operation that is
simple to manufacture and, in particular, that is fashioned monolithically
integrated and that works satisfactorily particularly in view of the
efficiency in the reception mode as well as in view of the transmission
properties, particularly in view of the efficiency in the transmission
mode.
It is inventively provided that the coupling of the light waveguide to the
semiconductor laser and reception diode fashioned monolithically
integrated in the semiconductor chip is fashioned such and the limiting
surface of the semiconductor chip at the light waveguide side is of such a
nature that, given an adequately low reflectivity of the laser emission
emitted by the laser that is required for adequate assurance of the laser
function, an optimally large part of the radiation received via the light
waveguide is incident into the semiconductor laser and reception diode. It
can thereby be provided in a development of the inventive solution that
the limiting surface of the semiconductor chip at the light waveguide side
has an essentially nearly completely dereflected surface or, respectively,
a surface having a substantially complete optical transmissivity for the
radiation received via the light guide. An inventive improvement of an
optoelectronic transmission-reception device is for providing such a low
reflectivity at the side of the laser (that particularly represents a
Fabry-Perot type) facing toward the fiber that an adequately permissible
laser function that the incoming reception power proceeds optimally
completely into the laser channel.
In a development of the present invention, this can be improved to the
effect that the light waveguide or, respectively, fiber is coupled
optimally well to the transmission-reception device. To this end, it can
be particularly provided that the coupling of the light waveguide to the
limiting surface of the semiconductor chip at the light waveguide side has
a thin matching layer applied to a surface of the limiting surface of the
semiconductor chip at the light waveguide side that faces toward the light
waveguide. This matching layer is of such a nature or, respectively, has
such a material that an optimally large part of the radiation received via
the light waveguide is incident into the semiconductor laser and reception
diode. An especially beneficial coupling of the light waveguide for the
purpose of a high incoming reception power derives when the material of
the thin matching layer applied to that surface of the limiting surface of
the semiconductor chip at the light waveguide side that faces toward the
light waveguide has a refractive index of at least approximately the
geometrical average of the values of the refractive index of the
semiconductor laser and reception diode and of the refractive index of the
material of the light waveguide. In a specific development, for example,
it can be provided that the refractive index of the material of the
matching layer has a value from about 1.5 to about 3.0 given a value the
refractive index of the semiconductor chip material of about 3.3 to about
3.8 and a reflective index of the material of the light waveguide of about
1.4 to about 1.6.
It can be additionally provided that the material of the matching layer has
a low optical absorption coefficient.
The back end of the laser should be highly reflective mirrored, so that the
limiting surface of the semiconductor laser facing away from the light
waveguide is provided with a surface that is highly reflective for the
laser light.
The material of the matching layer can thereby be beneficially selected
such that it also has beneficial mechanical and chemical properties in
addition to the suitable optical properties, particularly a low absorption
for the received radiation. The material, thus, should preferably be inert
relative to the neighboring materials, should be chemically stable, and
have a suitable consistency such that fabrication-conditioned tolerances
can be compensated or, respectively, a mechanically durable, uniform
filling of the space between the outer limiting surface of the
semiconductor chip and the end of the light waveguide to be coupled
›thereto! is assured.
In another preferred embodiment of the invention, it can be provided that a
field transformer for adapting the optical light output field from the
spatial dimensions of the light exit face of the laser to the entry face
of the coupled light waveguide is provided between the light-emitting end
of the semiconductor laser and that limiting surface of the semiconductor
chip facing toward the end of the light waveguide. Due to the improved
adaptation of the optical output field, such a field transformer enables
an overall reduction of the emitted or, respectively, received dissipated
powers. In a specific embodiment having a diameter of the fiber core of
about 9 .mu.m and a slightly larger diameter of the optical output field
of about 10 .mu.m, the field transformer enables an adaptation to the
geometry of the laser channel with typical dimensions of 0.1.mu. through
approximately 0.2 .mu.m in height and about 2 .mu.m through 3 .mu.m in
width.
It can be provided in another advantageous development of the invention
that a field transformer for adapting the optical light output field from
the spatial dimensions of the light exit face of the laser to the entry
face of the coupled light waveguide is provided between the light-emitting
end of the semiconductor laser and that limiting surface of the
semiconductor chip facing toward the end of the light waveguide.
In a particular embodiment of the invention, the monitor diode usually
required in laser operation can be omitted in that the power level at the
reception diode is acquired at the other end of the light waveguide and a
correction quantity that is potentially required is communicated, for
example, to the appertaining transmitter from time to time with a control
cell, said transmitter automatically readjusting the transmission power
via an evaluation of this information supplied by a correspondingly
fashioned evaluation circuit. When the optoelectronic
transmission-reception device is employed in a passive optical network
with many subscribers, such a device will come into consideration first
and foremost for the subscribers. The appertaining information about the
power of the individual subscriber can thereby be output from the exchange
end, addressed to the individual subscribers.
In another preferred embodiment, what is referred to a DFB laser
(distributed feed back laser) can be employed for the semiconductor laser
and reception diode fashioned monolithically integrated in the
semiconductor chip, this being distinguished by a cross-rifled resonator
(Bragg grating). Fundamentally, the standing waves (modes) in the laser
resonator have longitudinal parts (desired) relative to the emission
direction and transverse (undesired) relative to the emission direction.
When the Bragg grating is then implemented in the active zone, many small
sub-resonators form. The feedback events are distributed. First, the
effects of the transverse parts are suppressed further and only a few
modes form in longitudinal direction in the narrow grooves; second,
oppositely directed waves add up or, respectively, cancel (selection). As
a result thereof, what is referred to as the Bragg wavelength experiences
by far the greatest threshold amplification (natural amplification) and
the DFB laser works in single-mode operation. This functioning of the DFB
laser is known per se. In the inventive solution with a DFB laser, the
coupling of the light waveguide can again be improved by a field
transformer fashioned monolithically integrated in the semiconductor chip
as well as by providing the suitable selected matching layer between the
end of the light waveguide that the limiting surface of the semiconductor
chip facing toward it, whereby the arrangement of the coupling can be
fashioned in the form of a butt coupling or in the form of an intra-chip
fiber fastening.
When employing a DBR laser (distributed Bragg reflector laser) that also
serves as reception diode, it is likewise beneficial to fashion the end of
the laser toward the optical fiber with low reflectivity and to fashion
the other end of the laser that is arranged facing away from the optical
fiber with high reflectivity. In the known DBR laser, the Bragg grating
lies outside of the active zone, as a result whereof many discrete
resonator lengths are provided in the laser. As a result of the Bragg
condition, only a narrow band of laser modes is thereby propagatable,
whereby the band is also the narrower the shorter the period length and
the greater the depth of the filling. Single-mode operation with the Bragg
wavelength can also be achieved here.
Given fashioning with a DBR laser, a monitor diode that is fashioned
monolithically integrated in the semiconductor chip can be provided.
In another advantageous embodiment of the invention with, preferably, a DBR
laser and reception diode, two closely adjacent wavelengths are employed
that lie within the amplification window of the laser but can be separated
by grating reflectors, for example respectively in the first reflection
minimum. The first wavelength thereby serves for transmission and the
second wavelength serves for reception. In the reception case, the second
wavelength passes the grating reflectors at both sides of the laser diode
required for laser operation unattenuated. For increasing the reception
efficiency, the transmission-reception device can be fashioned such that
the second wavelength is advantageously reflected by a reflector at that
end of the arrangement facing away from the fiber.
In a comparable arrangement, a DFB laser and reception diode can thereby
also be employed.
For realizing a ping-pong operation with electrooptical transducers with
the desirable line lengths of about 10 km and about 32 subscribers at the
splitter, the inventive transmission-reception device allows a
significantly more cost-beneficial fashioning of, in particular,
electrooptical transmission-reception transducers at the subscriber side
as required for the introduction of the concept of fiber to the home,
especially with PON structure (passive optical network).
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic view for explaining a preferred application of an
optoelectronic transmission-reception device of the invention as
optoelectronic subscriber transducer at the subscriber-side end of the
light waveguide;
FIG. 2 depicts a curve for explaining the dependency of the transmission on
the refractive index of the material of the matching layer;
FIG. 3 is a schematic sectional view of an optoelectronic
transmission-reception device according to an exemplary embodiment of the
invention;
FIG. 4 is a schematic sectional view of an optoelectronic
transmission-reception device according to another exemplary embodiment of
the invention;
FIG. 5 is a schematic sectional view of an optoelectronic
transmission-reception device according to another exemplary embodiment of
the invention;
FIG. 6 is a schematic sectional view of an optoelectronic
transmission-reception device according to another exemplary embodiment of
the invention; and
FIG. 7 is a schematic sectional view of an optoelectronic
transmission-reception device according to another exemplary embodiment of
the invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The schematic view of FIG. 1 shows employment of an inventive
optoelectronic transmission-reception device 1 at the subscriber-side
terminal of a trunk line network for optical communication transmission in
the form of a passive optical network. The data transmission ensues
between an exchange-side terminal equipment 2 and a plurality of
subscriber-side network terminations 3 that are centrally coupled to the
exchange-side terminal equipment 2 in a star-shaped configuration via a
splitter 4 and via light waveguides 5. The terminal equipment 2 is
composed of a detector part 6 (exchange-side receiver) and of a laser part
7 (exchange-side transmitter), whereby the detector part 6 supplies an
information signal 8 about the analog subscriber level from which an
actuating variable 9 in digital form is derived for the laser current of
the laser part 7 to be controlled. At the optoelectronic
transmission-reception device 1 arranged at the subscriber side with a
transmission-reception laser chip fashioned monolithically integrated, a
digital actuating variable 10 for the laser current is derived due to the
monitor function and supplied for the control of the transmission part
according to reference character 11.
FIG. 3 shows a first exemplary embodiment of a subscriber-side
optoelectronic transmission-reception device 1 in greater detail. A DFB
semiconductor laser and reception diode 13, whose laser resonators are
formed by the two outer limiting surfaces 14 and 15 of the semiconductor
chip 12 that are arranged lying opposite one another, is fashioned
monolithically integrated in a semiconductor chip comprising an InP
substrate material. The laser light emitted by the semiconductor laser 13
is beamed into a light waveguide 16 coupled to the limiting surface 15 of
the semiconductor 12 at the side of the light waveguide 16. In the case
illustrated here, the light waveguide 16 represents a monomode fiber with
a fiber core 17 of silica glass. The coupling of the fiber end 18 to the
semiconductor chip 12 ensues in a butt coupling with a thin matching layer
20 of a material having a refractive index that essentially at least
approximately corresponds to the geometrical average of the values of the
refractive index of the material of the semiconductor laser and reception
diode and of the refractive index of the light waveguide introduced
between the limiting surface 15 of the semiconductor chip 12 and the
end-face limiting surface 19 of the fiber end 18. As derives according to
FIG. 2 from the illustration of the dependency of the transmission on the
refractive index of the matching layer 20, a value for the refractive
index of the matching layer that is derived from said geometrical average
delivers an especially high transmission of the received laser light.
Given a refractive index of 1.5 for the material of the light waveguide 16
and a refractive index of about 3.6 for the InP semiconductor material, an
optimum value of the refractive index of the matching layer lies in the
range from about 1.5 to about 3.0, particularly about 2.0 to about 2.5.
Coming into consideration as material for the matching layer 20 is an
optically transparent plastic material that, over and above enabling the
required optical properties, also enables beneficial mechanical and
chemical properties in view of a simple manufacture and optimally durable
and stable formation of the coupling of the fiber. Reference numeral 21
indicates an ultraviolet resin compound for the mechanically stable fixing
of the coupling of the fiber to the semiconductor chip. The surface of the
limiting surface 15 of the semiconductor chip 12 has very low reflectivity
i.e. it has such a low reflectivity that an adequate laser function is
just still assured. Compared thereto, the limiting surface 14 is provided
with a surface that is highly reflective for the laser light. In this way,
an optimally large part of the radiation incident from the light waveguide
16 is received by the semiconductor laser and reception diode 13. A field
transformer that serves for the adaptation of the optical light output
field and that is arranged between the light-emitting end 22 of the
semiconductor laser and the limiting surface 15 facing toward the end of
the light waveguide is schematically indicated with reference numeral 23.
FIG. 4 shows another exemplary embodiment of an inventive optoelectronic
transmission-reception device 1 with a DFB laser, whereby the coupling of
the fiber end 18 to the semiconductor chip 12 is fashioned in intra-chip
coupling. The fiber end 18 is thereby fastened completely within a
depression or, respectively, channel 24 fashioned in the semiconductor
chip 12. As shown in FIG. 4, the depression can have a shape corresponding
to the cylindrical form of the light waveguide 16 or can assume a V-shaped
form or similarly tapering form for better mechanical fastening. A thin
matching layer 20 having the properties recited in the description of the
exemplary embodiment according to FIG. 3 can again be applied between the
end-face limiting surface 25 at the floor of the depression 24 of the
semiconductor chip 12 and the end-face limiting surface 19 of the fiber
end 18.
FIG. 5 shows another exemplary embodiment of an inventive optoelectronic
transmission-reception device 1 with a DBR laser-reception diode 13 whose
end 26 facing toward the light waveguide 16 is fashioned with low
reflectivity and whose opposite end 27 is fashioned with high
reflectivity. The DBR laser-reception diode 13 has a monitor diode 28
likewise fashioned integrated in the semiconductor chip 12 allocated to
it, this monitor diode 28 delivering an actuating quantity for the
automatic control of the transmission current of the laser from the
received signal.
FIG. 6 and FIG. 7 shows especially advantageous embodiments with a laser
and reception diode 13 wherein two closely adjacent wavelengths are
employed that lie in the amplification window of the laser, but that can
be separated with reflectors. The wavelength 1 thereby serves for the
transmission and the wavelength 2 for the reception. In the embodiment of
FIG. 6 with a DBR laser and reception diode 13 and a monitor diode 28
following thereupon, reflectors 29, 30 and 31 in the form of grating
reflectors are fashioned within the semiconductor chip 12 or,
respectively, are of such a nature that the radiation with the wavelength
.lambda.1 serving for the transmission is mirrored at the laser reflector
29 with low reflectivity and at the laser reflector 30 with high
reflectivity and the radiation with the wavelength .lambda.2 serving for
the reception is highly reflected at the reflector 31 of the monitor diode
28 and is essentially not reflected at the laser reflectors 29 and 30. In
this way, the light radiation with the wavelength .lambda.2 can pass the
grating reflectors 29 and 30 at both sides of the laser diode required for
the laser operation unattenuated in the reception case and can be
reflected at the end of the arrangement by the reflector 31 for enhancing
the reception efficiency.
FIG. 7 shows a comparable arrangement upon employment of a DFB laser and
reception diode 13 and a monitor diode 28.
The invention is not limited to the particular details of the apparatus
depicted and other modifications and applications are contemplated.
Certain other changes may be made in the above described apparatus without
departing from the true spirit and scope of the invention herein involved.
It is intended, therefore, that the subject matter in the above depiction
shall be interpreted as illustrative and not in a limiting sense.
* * * * *
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