Optical waveguides – With disengagable mechanical connector – Optical fiber to a nonfiber optical device connector
Reexamination Certificate
2001-02-09
2003-04-01
Sanghavi, Hemang (Department: 2874)
Optical waveguides
With disengagable mechanical connector
Optical fiber to a nonfiber optical device connector
C385S089000, C385S092000, C385S093000, C359S199200
Reexamination Certificate
active
06540412
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an optical transceiver having a light emitting element and a light receiving element.
2. Description of the Related Art
An optical transceiver having a light receiving module and a light transmitting module is used for an optical transmission systems such as data links and optical LANs that use light as an information transmission medium. The light receiving module converts an optical signal transmitted via optical fibers to an electric signal and outputs the electric signal. The light transmitting module converts an electric signal to an optical signal. An optical transceiver in related art is configured as shown in FIG.
22
.
An optical transceiver
280
shown in
FIG. 22
includes a TO metal package
283
, an electronic circuit substrate
281
, a resin mold part
282
, and lead pins
284
. The TO metal package
283
is engaged with an optical connector. The electronic circuit substrate
281
has an electronic circuit for processing an electric signal corresponding to an optical signal transmitted or received to/from the optical connector formed thereon. The resin mold part
282
is used for fixing the TO metal package
283
and the electronic circuit substrate
281
. The lead pins
284
are used for connecting the electronic circuit substrate
281
with an external mounting substrate. The light emitting element and light receiving element, not shown in
FIG. 22
, are housed in the TO metal package
283
and protected from an external electromagnetic noise.
However, in the optical transceiver
280
of the related art, the electronic circuit substrate
281
is extended in a horizontal direction, that is, a direction where a light emitting element and a light receiving element were arranged in parallel to each other. Accordingly, it has not been impossible to narrow the spacing between the light emitting element and the light receiving element. As a result, in the related art, the optical transceiver suffered from a disadvantage that it could not support small-sized optical connectors.
Further, as the optical signal to be transmitted travels at a high speed, over 1 Gbps, the influence of an electromagnetic noise between a light emitting element and a light receiving element or between a driving circuit for the light emitting element and a circuit for the light receiving element becomes serious thus having adverse effects on the receiving sensitivity characteristics.
SUMMARY OF THE INVENTION
Accordingly, it is an object to provided a small-sized optical transceiver with a narrower spacing between a light emitting element and a light receiving element and with a structure that can realize stable operation in transmission speeds exceeding 1 Gbps.
An optical transceiver according to the invention comprises a receiver optical sub-module, a transmitter optical sub-module, and a housing to accommodate these modules. The receiver optical sub-module has a light receiving element for receiving an optical signal from a receiver optical fiber and a receiver electronic circuit substrate having an electronic circuit formed thereon. The electronic circuit processes output signals from the light receiving element. The transmitter optical sub-module has a light emitting element to transmit an optical signal to a transmitter optical fiber and a transmitter electronic circuit substrate having an electronic circuit formed thereon. The electronic circuit processes input signals to the light emitting element. The housing has a receptacle part with which an optical connector is engaged that accommodates the receiver optical fiber and the transmitter optical fiber. The receiver optical sub-module and the transmitter optical sub-module are attached to the housing. In this optical transceiver, the receiver electronic circuit substrate and the transmitter electronic circuit substrate are disposed opposite to each other. Preferably, the transmitter electronic circuit substrate may be substantially parallel to the receiver electronic circuit substrate in their longitudinal direction. Further, a surface of the transmitter electronic circuit substrate where the electronic circuit is formed may be substantially parallel to a surface of the receiver electronic circuit substrate where the electronic circuit is formed. The surface of the transmitter electronic circuit substrate where the electronic circuit is formed may be opposite to the surface of the receiver electronic circuit substrate where the electronic circuit is formed. Thus, by arranging the receiver electronic circuit substrate in an opposed position to the transmitter electronic circuit substrate, the receiver electronic circuit substrate and the transmitter electronic circuit substrate can be arranged in the close proximity.
In the optical transceiver, it is preferable that the optical transceiver further comprises an electrical shield plate arranged between the receiver optical sub-module and the transmitter optical sub-module. Thus, by providing an electrical shield plate, it is possible to reduce the effects of an electromagnetic noise mutually generated between the receiver optical sub-module and the transmitter optical sub-module. This electrical shield plate is preferably composed of a conducting plate having a grounding terminal.
In the optical transceiver, it is also preferable that the housing comprises a mounting portion on which the receiver optical sub-module and the transmitter optical sub-module are mounted and a conductive cover for covering the receiver optical sub-module and the transmitter optical sub-module and being coupled to the mounting portion. The cover has a grounding terminal. In this way, by providing a conductive cover to cover the receiver optical sub-module and the transmitter optical sub-module and to have the grounding terminal, it is possible to reduce the effects of an external electromagnetic noise on the receiver optical sub-module and the transmitter optical sub-module.
In the optical transceiver, it is preferable that the receiver optical sub-module further has a metal receiver optical sub assembly, the transmitter optical sub-module further has a metal transmitter optical sub assembly, and the receptacle part is engaged with an optical connector that accommodates the receiver ferrule and the transmitter ferrule. The metal receiver optical sub assembly accommodates a light receiving element therein and has a receiver sleeve for engaging with a receiver ferrule provided at the tip of the receiver optical fiber. The metal transmitter optical sub assembly accommodates a light emitting element and has a transmitter sleeve for engaging with a transmitter ferrule provided at the tip of the transmitter optical fiber.
In the optical transceiver, the receiver optical sub assembly may have a metal stem, a metal lens holder hermetic sealed to the metal stem, and a metal receiver sleeve.
In this way, via a configuration where metal members are combined, alignment of a light receiving element with an optical fiber is made easy and the electromagnetic noise is effectively reduced.
In the optical transceiver, the light receiving element may be mounted on a parallel-plate capacitor installed on the metal stem.
In this way, by mounting the light receiving element on a parallel-plate capacitor, it is possible to reduce the area of the stem and the bypass effect of an electromagnetic noise is provided for a signal whose transmission speed exceeds 1 Gbps.
In the optical transceiver, the receiver optical sub assembly may comprise five external lead pins and connected to a receiver electronic circuit substrate so that the length of the ground lead pin provided in the center of the metal stem may be shortest.
Via such a configuration, it is possible to enhance the resistance against an electromagnetic noise from a high-frequency wave whose transmission speed exceeds 1 Gbps.
In the optical transceiver, the receiver optical sub assembly and the transmitter optical sub assembly preferably have an operating speed equal to or greater than 1.0 Gbps.
I
Go Hisao
Mizue Toshio
Yonemura Ryugen
Knauss Scott A
Sanghavi Hemang
Smith , Gambrell & Russell, LLP
Sumitomo Electric Industries Ltd.
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