Journal of Lightwave Technology | Liu Z, Matsui Y, Schatz R, Khan F, Kwakernaak M, et al. | We demonstrate pulse generation at a repetition rate of 50 GHz. by gain switching an injection-locked dis...
50-GHz Repetition Gain Switching Using A Cavity-enhanced DFB Laser Assisted By Optical Injection Locking
Abstract
We demonstrate pulse generation at a repetition rate of 50 GHz by gain switching an injection-locked distributed feedback (DFB) laser. The small-signal BW of the DFB laser was enhanced from an intrinsic BW of 30 GHz to 52 GHz due to the joint effects of photon-photon resonance (PPR) and detuned loading. The detuned loading effect is achieved by exploiting the frequency-dependent cavity loss, which results in an increase of the effective differential gain, and correspondingly, the relaxation oscillation frequency. In addition to small-signal measurements, we show that the PPR and the detuned loading effects can also be utilized to improve large signal gain-switching, despite the dynamic changes of the detuned loading condition due to the large signal chirp. By modulating the laser with 50-GHz RF signals, we obtained 50-GHz repetition rate pulses from the gain-switched laser, confirming that the BW enhancement effects are still valid for large-signal modulation. Subsequently, we optically injection lock the gain-switched laser with strong external seeding light, which suppresses the chirp and creates coherent frequency tones with 50 GHz spacing. The optical injection locking (OIL) further enhances the large-signal BW, resulting in narrower pulse width of 9.5 ps (6.2 ps after deconvolution) in the time domain and three sideband peaks above 70% from the peak in the frequency domain (full width half maximum of 130 GHz). Assuming linear chirp, the pulse could be further compressed to 2.4 ps.
Publication Type: | Journal Article |
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Publication Sub Type | Article |
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Authors: | Liu Z, Matsui Y, Schatz R, Khan F, Kwakernaak M, Sudo T |
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Publisher: | Institute of Electrical and Electronics Engineers (IEEE) |
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Publication date: | 11/02/2020 |
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Pagination | 1 |
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Journal | Journal of Lightwave Technology |
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Status | Published |
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Print ISSN | 0733-8724 |
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DOI: | |
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Full Text URL: | |
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