Model-Based Bias Controller for a Mach-Zehnder Intensity Modulator

Svarny, J.; Chladek, Svatoslav

doi:10.1109/jlt.2021.3122460

Cited by 10 publications

(4 citation statements)

References 15 publications

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“…We consider the phase-dependent cosine component of Equation (1b) as the signal s = cos(φ) (7) and assume this signal to be extended periodically for all time. This aspect will become important for the calculation of the resulting spectrum.…”

Section: Calculation Of Mzm Output Signalmentioning

confidence: 99%

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Mach–Zehnder Modulator Output in Time and Frequency Domain—Calculation and Experimental Confirmation

2023

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The Mach–Zehnder intensity Modulator (MZM), named after Ludwig Mach and Ludwig Zehnder, is based on the corresponding interferometer. It splits light into two counter-rotating partial beams, which are later recombined with a controlled phase difference. The output of the MZM depends on the phase difference of the interferometer paths. This phase difference is usually adjusted by an electrical voltage applied to a Phase Shifter (PS) placed in one of the interferometer arms. For MZM applications in which the wavelength is changing, the applied voltage must be adjusted accordingly. We derived the equations describing the MZM output in the frequency domain for the case of a triangular PS voltage (necessary for a sinusoidal output) and compared the analytical results with measurements. Our setup uses an Optical Parametric Oscillator (OPO) with a tunable wavelength from 3.2–3.5 μm as the light source and a Lithium Tantalate (LT)-PS for the MZM’s phase modulation. The novel insights enable new control methods for MZMs particularly suited for spectroscopic applications where the wavelength is scanned or otherwise altered.

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Section: Calculation Of Mzm Output Signalmentioning

confidence: 99%

“…A bias voltage is the Direct Current (DC) component of the PS's control voltage. Furthermore, there are first approaches to model-based controls [7].…”

Section: Introductionmentioning

confidence: 99%

Mach–Zehnder Modulator Output in Time and Frequency Domain—Calculation and Experimental Confirmation

2023

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“…However, the control logic is relevant to modulation format and the precision is considered not enough for high-order modulation, then the dither-based method is deployed. The harmonic information of the dither can be used for feedback control [8]. The most common dither signal is the sine signal.…”

Section: Introductionmentioning

confidence: 99%

Numerical Analysis of Dither Induced Penalty for Automatic Bias Control Methods

Wu,

Zhong,

Dai

et al. 2024

IEEE Photonics J.

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The Mach-Zehnder modulator (MZM) is widely used in high-speed optical communication, and the stability of its bias point is the key to maintain the performance of the communication system. Numerous automatic bias control methods have been proposed to stabilize the bias point, which can be classified into power-based and dither-based methods. The power-based method features low-complexity and is considered of low-precision, thus it is usually applied to low-order modulation. In contrast, ditherbased method features high-complexity and is considered of highprecision, therefore it is usually applied to high-order modulation. This paper explores the bias impact mechanism and analyzes the impact of the bias and dither signal. Traditional view is that the performance of dither-based outperforms power-based ones. However, the impact of dither is ignored. Here we compare the performance of the power-based and dither-based method under fair conditions. The results show that the power-based method has higher SNR and better performance taking into account the impact of dither, which indicates that practically it is more suitable for high-order modulation.

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“…A comprehensive model-based bias controller has been introduced for a Mach-Zehnder intensity modulator, aimed at regulating the bias voltage to uphold the operating point deviation of the modulator. This approach relies on directly computing the operating point deviation through an analysis based on a fast Fourier transform, with an accurately set level of vector averaging [15]. Utilizing MZM with EDFLs has been reported in different publications as an intracavity element that is used to actively modelock the laser [16], suppress the intracavity noise [17], and create a stabilized multi-wavelength laser ring cavity [18,19].…”

Section: Introductionmentioning

confidence: 99%

10 Hz Stable Mode-locked Er-Fiber Laser

2023

JJP

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In this paper, a stable output at the reduction repetition rate from 80 MHz mode-locked Er-doped fiber laser (EDFL) was demonstrated by adjusting the operating point for external LiNbO3 Mach-Zehnder‎ electro-optic intensity modulator to suppress harmonic mode-locked pulses. More than 70% of the laser beam was launched into the external pigtail Mach-Zehnder intensity modulator using single mode fiber with collimating lens and fiber (ferrule connector) FC adapter. The optimum values of Mach-Zehnder modulator bias voltages V0 and Vπ (half wave voltage) which resulted in maximum and minimum laser output power to leave the modulator were found at 6.5 and 0.29 V, respectively. The best modulation was achieved for the RF modulating signal with an opening time of about 8 ns. For driving voltage equal to Vπ, a clean mode-locked pulse train was generated with a pulse shape and energy similar to the input pulse, albeit with a low repetition rate. The minimum repetition rate reached as low as 10 Hz, resulting in pulse energy and peak power of 0.32 nJ and 1.5 kW, respectively. Second-harmonic generation of the low repetition rate pulse train was also produced by using a PPLN crystal. This opens up the potential for using this laser in single photon detection experiments and as a seed laser for many applications. Keywords: Er-fiber laser, Passively mode-locked fiber laser, Nonlinear polarization rotation, Mach-Zehnder modulator, Fast electro-optic modulator. PACS: Fiber lasers, 42.55.Wd, Mode locking, 42.60.Fc.

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Model-Based Bias Controller for a Mach-Zehnder Intensity Modulator

Cited by 10 publications

References 15 publications

Mach–Zehnder Modulator Output in Time and Frequency Domain—Calculation and Experimental Confirmation

Mach–Zehnder Modulator Output in Time and Frequency Domain—Calculation and Experimental Confirmation

Numerical Analysis of Dither Induced Penalty for Automatic Bias Control Methods

10 Hz Stable Mode-locked Er-Fiber Laser

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