Frequency synchronization of Fourier domain harmonically mode locked fiber laser by monitoring the supermode noise peaks

Li, Feng; Zhang, Aiqin; Feng, Xian; Wai, P.K.A.

doi:10.1364/oe.21.030255

Cited by 5 publications

(1 citation statement)

References 21 publications

(37 reference statements)

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“…The WSL is widely used in optical sensing and optical coherence tomography (OCT) [21]. The WSL is of a broadband quality and its frequency changes linearly with time [22][23][24][25][26], which makes it a perfect frequency conversion carrier when combined with the dispersion control device.…”

Section: Introductionmentioning

confidence: 99%

Microwave Photonic Frequency Conversion Based on a Wavelength Swept Laser

et al. 2020

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Microwave photonic frequency conversion, with flexible tunability and a simple structure based on a wavelength swept laser (WSL), is proposed and experimentally demonstrated. In the proposed frequency conversion system, a broadband WSL was used to generate a frequency-chirped optical carrier, which was sent to a Mach Zehnder modulator (MZM). A microwave signal, with its frequency to be converted, was applied to the MZM. The modulated signal was then sent to a dispersive device, where the waveform was compressed or expanded depending on the dispersion of the dispersive device. After photodetection, a frequency up-converted or down-converted microwave signal was generated. The tuning of the conversion frequency was achieved by adjusting the chirp rate of the optical carrier from the WSL or the dispersion of the dispersive device. The proposed approach was experimentally demonstrated. A microwave signal, with its frequency at 5 GHz, was up-converted to 5.577 GHz and down-converted to 4.936 GHz. The quality of the frequency converted microwave signal was also evaluated. The conversion performance could be further improved by introducing a WSL with a high duty cycle.

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Section: Introductionmentioning

confidence: 99%

Microwave Photonic Frequency Conversion Based on a Wavelength Swept Laser

et al. 2020

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Impact of self-phase modulation on the operation of Fourier domain mode locked lasers

2023

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Fourier domain mode locked (FDML) lasers are a class of frequency-swept lasers that are used to generate optical pulses with a wide sweep range, high repetition rate, and a low instantaneous bandwidth. They are commonly used in sensing and imaging applications, especially in optical coherence tomography. Ideally, the aspired features in the design of FDML lasers include a high coherence length, large sweep bandwidth, adjustable output power, and a high signal to noise ratio (SNR). However, the SNR of the output signal of FDML lasers is often lower than desired due to the presence of several irregularities in the output signal pattern, most notably because of the frequent occurrence of sharp power dips, also known as holes. These power dips originate due to the nonlinear gain dynamics of the semiconductor optical amplifier (SOA) that is employed in FDML lasers, while the occurrence frequency and strength of these dips are determined by the interaction of the FDML laser components, which involve the SOA, the tunable Fabry–Perot filter, and the optical delay fiber. Suppressing these power dips not only increases the output signal quality in terms of SNR, but also precludes the accumulation of phase offsets between subsequent roundtrips and facilitates convergence. As both current and future applications of FDML lasers are likely to require a higher signal power, in this paper, we are going to investigate the effect of self-phase modulation (SPM) in the optical fiber on dip formation and convergence. Since fiber nonlinearity, intracavity signal power, and fiber length all contribute to SPM, investigation of the effect of SPM on the formation of power-dips and operational convergence is critical. More importantly, the phase-mismatch that is caused by fiber-based SPM cannot be compensated easily in an FDML laser as in the case of chromatic dispersion, which necessitates a strategy for minimizing fiber-based SPM to ensure operational convergence and to secure a lower limit for the SNR of the output signal of FDML lasers.

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