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Browse Prior Art Database

Open-Link Detection for Laser Safety in Fiber-Optic Communications

IP.com Disclosure Number: IPCOM000102310D
Original Publication Date: 1990-Nov-01
Included in the Prior Art Database: 2005-Mar-17
Document File: 3 page(s) / 84K

Publishing Venue

IBM

Related People

Nicoletta, C: AUTHOR [+2]

Abstract

This article describes a method of limiting the amount of optical power emitted from an open optical fiber link, to meet safety requirements. When the link is closed, power is increased for better communications.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 73% of the total text.

Open-Link Detection for Laser Safety in Fiber-Optic Communications

       This article describes a method of limiting the amount of
optical power emitted from an open optical fiber link, to meet safety
requirements.  When the link is closed, power is increased for better
communications.

      The open-link detection scheme described here assumes a duplex
link, as shown in Figure 1.  An identical link-detection circuit is
at each end of the link.  Each circuit can sense incoming laser
signals and control the operation of its local transmitting laser.
The circuits operate together by transmitting low power, low
frequency (below one megahertz) pilot tones from the lasers until
they have established that the optical link is closed in both
directions.  They then switch the lasers to full power and begin
transmitting data.  During data transmission, the low-power pilot
tones are superimposed on the full- power envelope of the data
waveform.  Their continued presence allows the open-link detection
system to keep the lasers operating at full power.

      Figure 2 shows a block diagram of the open-link detector at
either end of the link.  A low-bandwidth output from the optical
receiver brings the incoming signal to a pair of tone detectors, one
for each of the pilot tones. The tone detector outputs feed some
simple control logic which determines what the laser is allowed to
produce.  A tone generator produces the tones that the laser
transmits.

      Tab...