The linewidth of a mode-locked semiconductor laser caused by spontaneous emission: Experimental comparison to single-mode operation

Rush, David W.; Burdge, Geoffrey L.; Ho, P.‐T.

doi:10.1109/jqe.1986.1072907

Cited by 24 publications

(7 citation statements)

References 16 publications

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“…Originally, Eq. (8) had been derived for single-frequency continuous-wave lasers, but it has later been shown [10,11] that the same formula applies to all lines of an actively modelocked laser when the total average output power of the laser is used for P out (rather than e.g. the power in a particular line).…”

Section: Optical Phase Noise Of Actively Mode-locked Lasersmentioning

confidence: 99%

Optical phase noise and carrier-envelope offset noise of mode-locked lasers

et al. 2005

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The timing jitter, optical phase noise, and carrierenvelope offset (CEO) noise of passively mode-locked lasers are closely related. New key results concern analytical calculations of the quantum noise limits for optical phase noise and CEO noise. Earlier results for the optical phase noise of actively mode-locked lasers are generalized, particularly for application to passively mode-locked lasers. It is found, for example, that mode locking with slow absorbers can lead to optical linewidths far above the Schawlow-Townes limit. Furthermore, modelocked lasers can at the same time have nearly quantum-limited timing jitter and a strong optical excess phase noise. A feedback timing stabilization via cavity length control can, depending on the situation, reduce or greatly increase the optical phase noise, while not affecting the CEO noise. Besides presenting such findings, the paper also tries to clarify some basic aspects of phase noise in mode-locked lasers.PACS 42.50.Lc; 42.60.Fc IntroductionThe noise properties of mode-locked lasers, in particular the timing jitter [1, 2], the optical phase noise, and the carrier-envelope offset (CEO) noise [3,4], are important for many applications, e.g. in frequency metrology and data transmission. These types of noise can have different origins, the most important of which are usually mechanical vibrations of the laser cavity, thermal effects in gain medium and/or laser cavity, and quantum fluctuations. As is well known, the latter are related mainly to spontaneous emission in the gain medium and to vacuum noise entering the laser cavity through the output coupler mirror and other elements with optical losses. Depending on the circumstances, the noise performance can be close to quantum limited or many orders of magnitude above the quantum limit. One may expect that quantum-limited performance in terms of timing jitter and optical phase noise should usually come in combination, but in the following it will be demonstrated that e.g. mirror vibrations can lead to strongly enhanced optical phase noise,

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Section: Optical Phase Noise Of Actively Mode-locked Lasersmentioning

confidence: 99%

Optical phase noise and carrier-envelope offset noise of mode-locked lasers

et al. 2005

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“…It is also known that a mode-locked pulse train's temporal coherence is inversely related to longitudinal mode linewidth [8]. For pulses separated in time by more than the coherence time, we expect to see no coherence, and, importantly, no noise correlation.…”

Section: Introductionmentioning

confidence: 87%

Study of White Noise Corner Frequency Location in Residual Phase Noise Measurement with Short and Long Cavity Lengths

Bagnell

Klee

Delfyett

2015

Frontiers in Optics 2015

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Abstract:We present an investigation of the white noise plateau in residual phase noise measurement of an optical frequency comb for short and long external laser cavity lengths.OCIS codes: (140.5960) Semiconductor Lasers; (140.4050) Mode-locked lasers MotivationSemiconductor harmonically mode-locked lasers have a number of features which make them attractive for use in communications, sampling, and metrology applications [1,2] For some of these applications, low timing jitter and narrow optical comb linewidth is required for good sampling resolution or increased stability.In semiconductor phase noise performance plots, we generally distinct characteristics at low, middling, and high offset frequencies relative to the carrier [3,4]. For good phase noise performance at high offset frequencies, we can implement a high finesse intra-cavity to suppress competing longitudinal mode-groups [5], and we can lower the shot noise floor by increasing photodetected optical power. In this submission, we address phase noise performance at middling offset frequencies corresponding to the white noise plateau. By decreasing optical linewidth, the corner, or "knee" frequency of the white noise plateau should also decrease proportionately [6], and we aim to hit the shot noise floor at lower offset frequencies and thereby reduce timing jitter. BackgroundIt is well known that laser cavity length determines longitudinal mode linewidth [7]. It is also known that a mode-locked pulse train's temporal coherence is inversely related to longitudinal mode linewidth [8]. For pulses separated in time by more than the coherence time, we expect to see no coherence, and, importantly, no noise correlation. Thus the noise contribution at low offset frequencies is dominated by uncorrelated white noise. This result has been shown in a previous publication without the use of the etalon to suppress supermode contributions to phase noise [6], and here we will attempt to implement the concept into our existing laser architecture [9]. Setup and DataThe laser's setup is shown in Fig. 1 and a similar architecture is discussed in [9]. Here we perform measurements at the shortest manageable cavity length (22m, f0 = 9MHz) and for a longer cavity length (351 m, f0 = 570 kHz). Fig. 2 shows the change in knee location for the residual phase noise measurement when bypassing the etalon in the laser (not PDH-locked). Fig. 3 shows the residual phase noise measurement for the short cavity. As of the time of this submission, the PDH lock on the longer cavity is limited due to the higher required dynamic range for the fiber stretcher, but the dashed line in Fig. 3 shows where we expect to measure the new knee location once we have ability to stabilize the laser. For equal shot noise floor and noise power at 1 Hz offset, we expect a reduction in timing jitter between 10% and 20%. This represents a promising improvement in the timing jitter of our optical frequency comb sources. References[1] P.

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“…[37], [38]. As early as 1962, Mandeli and Wolfs first proposed the relation between the coherence time Δτ and the bandwidth Δν.…”

Section: Theoretic Model Of the Optical Spectrum Of Single-mode LImentioning

confidence: 99%

Harmonic Mode-Locking of 10-GHz Directly Modulated Weak-Resonant-Cavity Fabry–Perot Laser Diode in Self-Feedback Fiber Ring

Lee

Chi

Tsai

et al. 2013

IEEE J. Select. Topics Quantum Electron.

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Harmonic mode-locking of a directly modulated weak-resonant-cavity Fabry-Perot laser diode (WRC-FPLD) at 10 GHz via the self-feedback of a fiber ring is demonstrated. The WRC-FPLD directly modulated at 10 GHz simultaneously functions as the gain medium and the active mode-locker in the self-feedback ring. The competition between the gain-switched lasing mechanism inside the WRC-FPLD and the harmonic modelocking mechanism of the incorporated self-feedback fiber ring is monitored. The enhanced mode-locking force can be achieved at self-feedback ratio of 90% and modulation power of 28 dBm. The evolution of pulsating dynamics is dependent with modulation frequency, which enhances the mode-locking and shortens the pulsewidth at the longitudinal mode spacing. A mode-locking theory is used to simulate the coupled-cavity self-injected WRC-FPLD fiber ring. When the lasing mechanism transfers from intracavity gain-switching to intercavity harmonic mode-locking, the longitudinal mode of the WRC-FPLD is broadened with the mode extinction reduced from maximum to minimum. Due to the transformation from the gain-switching to harmonic mode-locking, the coupled-cavity self-feedback WRC-FPLD fiber ring delivers a pulsewidth of 22 ps, a timing jitter of 153 fs, a pulse extinction ratio of 13.65 dB, and a spectral linewidth of 7.6 nm, by setting the WRC-FPLD bias at three times above threshold (∼60 mA) and the intracavity feedback ratio of 90%.

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The linewidth of a mode-locked semiconductor laser caused by spontaneous emission: Experimental comparison to single-mode operation

Cited by 24 publications

References 16 publications

Optical phase noise and carrier-envelope offset noise of mode-locked lasers

Optical phase noise and carrier-envelope offset noise of mode-locked lasers

Study of White Noise Corner Frequency Location in Residual Phase Noise Measurement with Short and Long Cavity Lengths

Harmonic Mode-Locking of 10-GHz Directly Modulated Weak-Resonant-Cavity Fabry–Perot Laser Diode in Self-Feedback Fiber Ring

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