Browse Prior Art Database

Led/Laser-Compatible Fiber-Optic Link

IP.com Disclosure Number: IPCOM000119612D
Original Publication Date: 1991-Feb-01
Included in the Prior Art Database: 2005-Apr-02
Document File: 2 page(s) / 61K

Publishing Venue

IBM

Related People

Boerstler, DW: AUTHOR

Abstract

When a sensitive fiber-optic receiver is operated with a laser source, a low-loss link will cause the receiver to saturate due to the high output optical power of the laser.

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This is the abbreviated version, containing approximately 66% of the total text.

Led/Laser-Compatible Fiber-Optic Link

      When a sensitive fiber-optic receiver is operated with a
laser source, a low-loss link will cause the receiver to saturate due
to the high output optical power of the laser.

      A fiber-optic receiver design is proposed which contains a pin
photodiode, a preamp, a postamp, and a decision circuit connected in
series, as shown in Fig. 1.  The light inpinging on the photodiode is
amplified by the low noise preamp, linearly amplified by the postamp,
and converted to a logic level by the decision circuit.  Connected to
the output of the postamp is a positive peak detector, which holds
the peak voltage level of the linearly amplified signal.  The output
of the peak detector is connected to two comparators.  The first
comparator has its positive input connected to the peak detector, its
negative input connected to a reference voltage "Vhi", and its output
signal indicates the input power level has exceeded the "Vhi"
reference level defined as the maximum power level before saturation
occurs in the receiver.  The second comparator has its negative input
connected to the peak detector, its positive input connected to a
reference voltage "Vlo", and its output signal indicates the input
power level has dropped below the minimum power level for which
proper operation can be guaranteed.

      A laser transmitter is proposed (see Fig. 2) which has a serial
data input for the information signal and an input "BOOST" signal.
I...