Browse Prior Art Database

Electronic Beam Switching in Injection Lasers

IP.com Disclosure Number: IPCOM000094510D
Original Publication Date: 1965-Feb-01
Included in the Prior Art Database: 2005-Mar-06
Document File: 2 page(s) / 31K

Publishing Venue

IBM

Related People

Williams, HB: AUTHOR [+2]

Abstract

For modulating the light output of a semiconductor laser, the laser can be provided with a primary contact that is energized with current just below the threshold for lasing. A secondary contact is energized with a small current that is varied according to the desired light output. The two devices use this effect with two or more secondary contacts to provide beam direction switching.

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Electronic Beam Switching in Injection Lasers

For modulating the light output of a semiconductor laser, the laser can be provided with a primary contact that is energized with current just below the threshold for lasing. A secondary contact is energized with a small current that is varied according to the desired light output. The two devices use this effect with two or more secondary contacts to provide beam direction switching.

In the device of drawing A, the laser cavity is constructed so that lasing can occur in either of the directions X and Y in which one of the two secondary contacts is aligned with the primary contact. Surfaces of the laser in the directions of lasing are polished or silvered. Other surfaces can be roughened as the speckled area of the drawing represents. The primary contact is energized with a current IB slightly below the threshold value. A selected secondary contact is energized with a small current IX or IY to produce lasing in the corresponding direction. Such a laser is useful in a communications system for signaling a selected one of two receiving stations located in the directions of lasing.

The device of drawing B provides more directions of beam switching. The laser cavity is cylindrical with the primary contact located at the center of the diode and the secondary contacts on different radii. The cylindrical surface to the left in the drawing is silvered so that lasing occurs along the radius of the energized contact.

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