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Browse Prior Art Database

Low-Threshold Vertical Emitting Laser

IP.com Disclosure Number: IPCOM000101030D
Original Publication Date: 1990-Jun-01
Included in the Prior Art Database: 2005-Mar-16
Document File: 2 page(s) / 46K

Publishing Venue

IBM

Related People

Van Zeghbroeck, BJ: AUTHOR

Abstract

This article describes a low threshold laser structure with a horizontal gain section, 45-degree mirrors with total reflection on top of an A1GaAs dielectric stack. The structure is vertically emitting (through the substrate) and can be as short as 10 mm with a threshold of 200 mm.

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This is the abbreviated version, containing approximately 88% of the total text.

Low-Threshold Vertical Emitting Laser

       This article describes a low threshold laser structure
with a horizontal gain section, 45-degree mirrors with total
reflection on top of an A1GaAs dielectric stack.  The structure is
vertically emitting (through the substrate) and can be as short as 10
mm with a threshold of 200 mm.

      As shown in the figure, the device consists of a regular Single
Quantum Well (SQW) Ridge-GRINSCH laser section with the exception
that, instead of vertical mirrors, 45-degree mirrors are etched at
each end.  These mirrors reflect the light into the substrate by
total internal reflection where it is reflected back by an A1GaAs
dielectric stack, consisting of, e.g., 20 periods of 1/4 lambda
layers, and acting as a distributed bragg reflector. This structure
combines the high reflectivity of the dielectric stack with the large
gain of the GRINSCH structure.  The vertical emission is obtained by
etching the substrate up to the dielectric mirror.  An additional
mirror is added to one end of the laser to further reduce the
threshold.  The n-contact can be made either on the back of the wafer
or on top with the additional advantage of lower contact resistance.

      Assuming a waveguide loss of 3 cm -1 and a gain of 33 cm-1
at a current density of 200 A/cm-2, a mirror reflectivity of 98%
respectively 99%, and a 10 mm long gain section, we obtain a
threshold current of 200 mm.

      A similar structure using a Double Heterostruc...