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Multimode Tunable cw GaAs Injection Laser

IP.com Disclosure Number: IPCOM000077356D
Original Publication Date: 1972-Jul-01
Included in the Prior Art Database: 2005-Feb-25
Document File: 2 page(s) / 26K

Publishing Venue

IBM

Related People

Ludeke, R: AUTHOR

Abstract

The structure described achieves coherent cw radiation from a semiconductor (GaAs) diode, with spectral purity and at power levels not achievable by conventional methods. Radiation from a conventional lasing diode may be monochromatic, but this situation is only observed at very low - power levels of a few milliwatts. Upon increasing the excitation level of the laser, polychromatic radiation emerges.

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Multimode Tunable cw GaAs Injection Laser

The structure described achieves coherent cw radiation from a semiconductor (GaAs) diode, with spectral purity and at power levels not achievable by conventional methods. Radiation from a conventional lasing diode may be monochromatic, but this situation is only observed at very low - power levels of a few milliwatts. Upon increasing the excitation level of the laser, polychromatic radiation emerges.

The structure illustrated in the figure achieves monochromatic cw radiation at power levels in excess of 100 mw. Furthermore, the output radiation is tunable over a range of wavelength of + 75 angstroms about a center wavelength of approximately 8520 angstroms.

The active device 1 consists of a conventional lasing diode such as gallium arsenide, the Q of which is purposely spoiled by the application of an antireflection coating 2, so that the new device will not lase by itself. The device is mounted on the cold finger of an optical dewar 3, and maintained at 77 degrees K or other convenient cryogenic temperature. The emitted radiation from a junction region 4 of the electrically excited diode 1 is collimated by lens 5 and projected onto a dispersive element (grating or prism) 6. The latter selects, by proper rotational adjustment about axis 7, a narrow-band region, determined by the dispersive ability of element 6, which is refocused by lens 5 onto the junction region 4 of diode 1. If a threshold condition is exceeded, that i...