EP0759666A2
Expired / Lapsed
EP
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Optical telecommunication module
Assignee: Fujitsu Ltd
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Filing: 1996-08-09
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Granted: —
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Expires: 2016-08-09
Abstract
Abstract An optical module includes a photodiode disposed in front of a laser diode with an offset from an optical axis of the laser diode, for monitoring the power of an optical beam emitted from the laser diode in a forward direction. The optical module further achieves switching between a transmission mode and a reception mode in response to a drive current supplied to the laser diode. <IMAGE>
Inventors
- 👤 Tomohisa Ishikawa
- 👤 Katsuhiko Hakomori
- 👤 Tatsuya Nishimura
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-01 18:48
CPC Classifications
H; H04; H04B; H04B10/00; H04B10/40; H04J; H04J3/00; H04B10/07; H04B10/075; H04B10/079; H04B10/0795
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
314 words
An optical telecommunication module, comprising: an optical transceiver (11A) adapted for coupling to an optical transmission line (1) for sending out an outgoing optical transmission signal therealong and for receiving an incoming optical transmission signal therefrom; said optical transceiver including a light emitting device (18) supplied with a transmission signal for emitting an optical signal in response thereto, an optical coupler (14) adapted for coupling to the optical transmission line (1), the optical coupler being connected optically to the light emitting device for injecting the optical signal emitted from the light emitting device into the optical transmission line (1) as the outgoing optical transmission signal, and a photodetection device (23) connected optically to the optical coupler (14) for receiving the incoming optical transmission signal from the optical transmission line (1), the photodetector producing a reception signal in response thereto; a drive unit (12A) for driving the optical transceiver (11A), said drive unit including a drive circuit (30A) feeding the transmission signal to the light emitting device (18), an automatic power control circuit (31) for controlling a drive current of the light emitting device such that the optical signal emitted from the light emitting device has a predetermined, constant optical power, an automatic gain control circuit (34) for controlling a level of the reception signal at a predetermined level, and a transmission/reception switching circuit (36A) for selectively activating the automatic power control circuit and the automatic gain control circuit, such that the automatic power control circuit is activated in a transmission mode for transmitting the outgoing optical signal and that the automatic gain control circuit is activated in a reception mode for receiving the incoming optical signal; and said optical telecommunication module further includes a monitoring photodetection device (19A) such that the monitoring photodetection device detects a part of the optical signal emitted from the light emitting device for injection into the optical transmission line.
Claim 2
Dependent Claim
64 words
An optical module as claimed in claim 1, wherein said transmission/reception switching circuit (36A) is supplied, from the drive circuit (30A), a status signal indicative of the transmission mode and the reception mode, for causing a selective activation of said automatic power control circuit (31) and said automatic gain control circuit (34), by producing a switching control signal in response to said status signal.
Claim 3
Dependent Claim
28 words
An optical module as claimed in claim 2, wherein said status signal is a drive current supplied from said drive circuit (30A) to said light emitting device (18).
Claim 4
Dependent Claim
52 words
An optical module as claimed in claim 2, wherein said transmission/reception switching circuit (36A) produces said switching control signal such that said switching control signal rises in response to a leading edge of said status signal and falls in response to a trailing edge of said status signal with a predetermined delay.
Claim 5
Dependent Claim
30 words
An optical module as claimed in claim 1, wherein said monitoring photodetection device (19A) is used commonly for said photodetection device (23) used for receiving the incoming optical transmission signal.
Claim 6
Dependent Claim
86 words
An optical module, comprising: a base (17A); a light emitting device (18) mounted upon said base for emitting an output optical beam in a forward direction along a predetermined optical axis; a photodetection device (19A) mounted upon said base at said forward direction of said light emitting device, said photodetection device being mounted with an offset from said predetermined optical axis; wherein said photodetection device is inclined toward said light emitting device for detecting a part of said optical beam emitted from said light emitting device.
Claim 7
Dependent Claim
26 words
An optical module as claimed in claim 6, wherein said optical module further includes a lens (20) in optical alignment with said light emitting device (18).
References Cited (Backward Citations)
No citation records indexed.
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