TY - JOUR
T1 - Photonic microwave generation and transmission using direct modulation of stably injection-locked semiconductor lasers
AU - Hwang, Sheng Kwang
AU - Chan, Sze Chun
AU - Hsieh, Shie Chin
AU - Li, Cheng Yu
N1 - Funding Information:
S.K. Hwang's work is fully supported by the National Science Council of Taiwan under Contract No. NSC97-2112-M-006-012-MY2 and NSC99-2112-M-006-013-MY3 , and S.C. Chan's work is fully supported by a grant from City University of Hong Kong under Project No. 7008046 and a grant from the Research Grants Council of Hong Kong , China under Project No. CityU 111308 .
PY - 2011/7/1
Y1 - 2011/7/1
N2 - Direct modulation of a semiconductor laser subject to stable injection locking is capable of generating microwave subcarriers that are broadly frequency-tunable, more than 4 times its free-running relaxation resonance frequency, and are highly sideband-asymmetric, more than 22 dB. The latter characteristic makes the laser system particularly attractive for radio-over-fiber applications. Therefore, such modulation sideband asymmetry, its underlying mechanism, and its effect on chromatic dispersion-induced microwave power variation are extensively studied, in particular, over a broad range of injection conditions. Mappings showing integrated and global understandings of the modulation sideband asymmetry together with the modulation frequency enhancement are obtained accordingly. Interestingly, it is found that the microwave frequency can be tuned over a broad range while keeping a similar level of modulation sideband asymmetry and vice versa, either of which is achieved by simply changing the injection condition. This, therefore, considerably adds the flexibility and re-configurability to the laser system. The cavity resonance shift due to injection locking is responsible for not only the enhanced modulation frequency but also the modulation sideband asymmetry, where a modification in its previous interpretation is obtained for explanation. The modified modulation characteristics are strong functions of the linewidth enhancement factor, making it possible to choose lasers with proper values of the factor for different photonic microwave characteristics.
AB - Direct modulation of a semiconductor laser subject to stable injection locking is capable of generating microwave subcarriers that are broadly frequency-tunable, more than 4 times its free-running relaxation resonance frequency, and are highly sideband-asymmetric, more than 22 dB. The latter characteristic makes the laser system particularly attractive for radio-over-fiber applications. Therefore, such modulation sideband asymmetry, its underlying mechanism, and its effect on chromatic dispersion-induced microwave power variation are extensively studied, in particular, over a broad range of injection conditions. Mappings showing integrated and global understandings of the modulation sideband asymmetry together with the modulation frequency enhancement are obtained accordingly. Interestingly, it is found that the microwave frequency can be tuned over a broad range while keeping a similar level of modulation sideband asymmetry and vice versa, either of which is achieved by simply changing the injection condition. This, therefore, considerably adds the flexibility and re-configurability to the laser system. The cavity resonance shift due to injection locking is responsible for not only the enhanced modulation frequency but also the modulation sideband asymmetry, where a modification in its previous interpretation is obtained for explanation. The modified modulation characteristics are strong functions of the linewidth enhancement factor, making it possible to choose lasers with proper values of the factor for different photonic microwave characteristics.
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U2 - 10.1016/j.optcom.2011.03.066
DO - 10.1016/j.optcom.2011.03.066
M3 - Article
AN - SCOPUS:79955881887
VL - 284
SP - 3581
EP - 3589
JO - Optics Communications
JF - Optics Communications
SN - 0030-4018
IS - 14
ER -