Browse Prior Art Database

WAVELENGTH DEMULTIPLEXING DETECTOR

IP.com Disclosure Number: IPCOM000025592D
Original Publication Date: 1986-Jun-30
Included in the Prior Art Database: 2004-Apr-04
Document File: 4 page(s) / 162K

Publishing Venue

Xerox Disclosure Journal

Abstract

In many optical communication systems, it would be advantageous to use light transmission at two different wavelengths. One light wavelength could be modulated at high rates, e g 10 Mb/sec or higher, and carry normal Ethernet protocol signals whereas the second light wavelength could be modulated at a lower rate, e,g ,64 Kb/sec for voice transmission In order to lower system cost, it would be advantageous for a single detector to sense both signals

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 54% of the total text.

Page 1 of 4

XEROX DISCLOSURE JOURNAL

WAVELENGTH D E MULTIPLEXING DETECTOR us c1.357/30 Donald R. Scifres
Ronald V. Schmidt
Stig B Hagstrom

Proposed Classification

Xnt. c1 HOll27/14

In P (SUBSTRATE)

Volume 11 Number 3 MaylJune 1986

[This page contains 1 picture or other non-text object]

Page 2 of 4

WAVELENGTH DEMULTIPLEXlNG DETECTOR (Cont'd)

In many optical communication systems, it would be advantageous to use light transmission at two different wavelengths. One light wavelength could be modulated at high rates, e g 10 Mb/sec or higher, and carry normal Ethernet protocol signals whereas the second light wavelength could be modulated at a lower rate, e,g ,64 Kb/sec for voice transmission In order to lower system cost, it would be advantageous for a single detector to sense both signals

We describe here an improved detector in which crosstalk is reduced by incorporating a wavelength selective multilayer filter within the detector and represents an improvement over the demultiplexing photodetectors of the type disclosed in U S. Patents 4,301,463 and 4,213,138

The detector 10 1s shown in Figure 1 and can be identical to the detector shown in U S Patent 4,213,138 except for intermedaate layer 104 Detector PO

comprises substrate 101 upon which are epitaxially deposited layer 102 of p- InP, layer 103 (Q1) of n-Ing TGao 3Aso 66Po 34, multi-stack filter layer 104 comprising alternating thin layers of InP (104A) and InGaAsP (204B), layer 105 (Q2) of n-In0 .saGao 2lAso 46Po 54, and window layer 106 of n-ImP

After crystal growth, an anneal is performed to cause Zn diffusion from layer 102 into the (&I) layer 103 to Form a p-njunctaon 10'7 above interface I08 A second p-n junction 109 as formed into layer 105 via a Zn diffusion through the top surface of detector 10 As a result of this latter selective diffusion, the p- type regon 110 is restricted to a central region so that electrical contact can be established with the n-sade of p-n junctions 107 and 109 via metal contact ring 1 f I on the top surface of detector 10

Detector 10 is a three terminal device, one terminal 111 and 13.3 making contact to the common m-region ofjunctions 107 and 109, a second terminal 112 making contact to p-regyon PfQ and a third contact 113 making contact to p-substrate 101. To operate detector 10 as a demodulator, junctions 107 and PO9 are reversed biased via source 114, whose positive terminal is connected to contact 1 P 1 and whose negatlve terminal is connected respectively through load resistors 115 and 116...