Improvements in Direct Pulse Code Modulation of Semiconductor Lasers by Optical Feedback

Kohroh KOBAYASHI

Improvements in Direct Pulse Code Modulation of Semiconductor Lasers by Optical Feedback

Kohroh KOBAYASHI

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As a new method to improve pulse code modulation properties of semiconductor lasers, optical feedback is proposed where a part of the light output from a modulated laser is fed back into itself, with a time delay considerably less than one relaxation oscillation (RO) period. Rate equation approach is applied to investigate the modulation characteristics. Modulation bit rates for small pattern effects depend on the RO period and the current pulse width, and they appear discontinuously. By optical feedback, the RO period increases, and it becomes possible to decrease pattern effects at any given modulation period, if it is larger than the RO period without optical feedback. For current pulses with a short duration, output waveforms are improved by optical feedback through increase in the first RO spike width and elimination of its second spike. In preliminary experiments, using GaAs-Al_XGa_1XAs double heterostructure lasers with a combination of a microlens and a flat mirror, qualitative agreements were obtained between theoretical and experimental results. Improvements in the modulated output waveforms were observed for PCM-RZ pulses at up to 500 Mb/s.

Publication: IEICE TRANSACTIONS on transactions Vol.E59-E No.12 pp.8-14

Publication Date: 1976/12/25

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Type of Manuscript: PAPER

Category: Optical and Quantum Electronics

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Kohroh KOBAYASHI

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Kohroh KOBAYASHI, "Improvements in Direct Pulse Code Modulation of Semiconductor Lasers by Optical Feedback" in IEICE TRANSACTIONS on transactions, vol. E59-E, no. 12, pp. 8-14, December 1976, doi: .
Abstract: As a new method to improve pulse code modulation properties of semiconductor lasers, optical feedback is proposed where a part of the light output from a modulated laser is fed back into itself, with a time delay considerably less than one relaxation oscillation (RO) period. Rate equation approach is applied to investigate the modulation characteristics. Modulation bit rates for small pattern effects depend on the RO period and the current pulse width, and they appear discontinuously. By optical feedback, the RO period increases, and it becomes possible to decrease pattern effects at any given modulation period, if it is larger than the RO period without optical feedback. For current pulses with a short duration, output waveforms are improved by optical feedback through increase in the first RO spike width and elimination of its second spike. In preliminary experiments, using GaAs-Al_XGa_1XAs double heterostructure lasers with a combination of a microlens and a flat mirror, qualitative agreements were obtained between theoretical and experimental results. Improvements in the modulated output waveforms were observed for PCM-RZ pulses at up to 500 Mb/s.
URL: https://global.ieice.org/en_transactions/transactions/10.1587/e59-e_12_8/_p

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@ARTICLE{e59-e_12_8,
author={Kohroh KOBAYASHI, },
journal={IEICE TRANSACTIONS on transactions},
title={Improvements in Direct Pulse Code Modulation of Semiconductor Lasers by Optical Feedback},
year={1976},
volume={E59-E},
number={12},
pages={8-14},
abstract={As a new method to improve pulse code modulation properties of semiconductor lasers, optical feedback is proposed where a part of the light output from a modulated laser is fed back into itself, with a time delay considerably less than one relaxation oscillation (RO) period. Rate equation approach is applied to investigate the modulation characteristics. Modulation bit rates for small pattern effects depend on the RO period and the current pulse width, and they appear discontinuously. By optical feedback, the RO period increases, and it becomes possible to decrease pattern effects at any given modulation period, if it is larger than the RO period without optical feedback. For current pulses with a short duration, output waveforms are improved by optical feedback through increase in the first RO spike width and elimination of its second spike. In preliminary experiments, using GaAs-Al_XGa_1XAs double heterostructure lasers with a combination of a microlens and a flat mirror, qualitative agreements were obtained between theoretical and experimental results. Improvements in the modulated output waveforms were observed for PCM-RZ pulses at up to 500 Mb/s.},
keywords={},
doi={},
ISSN={},
month={December},}

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TY - JOUR
TI - Improvements in Direct Pulse Code Modulation of Semiconductor Lasers by Optical Feedback
T2 - IEICE TRANSACTIONS on transactions
SP - 8
EP - 14
AU - Kohroh KOBAYASHI
PY - 1976
DO -
JO - IEICE TRANSACTIONS on transactions
SN -
VL - E59-E
IS - 12
JA - IEICE TRANSACTIONS on transactions
Y1 - December 1976
AB - As a new method to improve pulse code modulation properties of semiconductor lasers, optical feedback is proposed where a part of the light output from a modulated laser is fed back into itself, with a time delay considerably less than one relaxation oscillation (RO) period. Rate equation approach is applied to investigate the modulation characteristics. Modulation bit rates for small pattern effects depend on the RO period and the current pulse width, and they appear discontinuously. By optical feedback, the RO period increases, and it becomes possible to decrease pattern effects at any given modulation period, if it is larger than the RO period without optical feedback. For current pulses with a short duration, output waveforms are improved by optical feedback through increase in the first RO spike width and elimination of its second spike. In preliminary experiments, using GaAs-Al_XGa_1XAs double heterostructure lasers with a combination of a microlens and a flat mirror, qualitative agreements were obtained between theoretical and experimental results. Improvements in the modulated output waveforms were observed for PCM-RZ pulses at up to 500 Mb/s.
ER -