Parallel measurement of multiple linear polarization modes in few-mode optical fibers using spatial light modulators

Zhao, Yuyuan; Huang, Sujuan; Yan, Cheng

doi:10.1117/1.oe.58.9.094103

Cited by 4 publications

(4 citation statements)

References 23 publications

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“…However, it is challenging to investigate the modal components at the multimode output fiber, owing to the immaturity of the equipments and technologies in our laboratory. This issue could be addressed in the future by utilizing schemes adopted in [39][40][41][42][43][44][45].…”

Section: Multimode Qml Operationmentioning

confidence: 99%

All-fiber low threshold tunable multimode Q-switched mode locked fiber laser using a few mode Er-doped fiber

Fan¹,

Zhang²,

Ning³

et al. 2023

Laser Phys.

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We report an all-fiber low threshold (70 mW) multimode Q-switched mode-locked (QML) fiber laser at 1.5 μ m. Nonlinear polarization rotation and a few mode Er-doped fiber (FM-EDF) were both adopted to achieve a low threshold QML operation initially, and the later experimental results showed and verified that the FM-EDF was the key factor of the QML pulses generation. A multimode QML state at 70 mW pump power was obtained with an 18 μs Q-switched pulse width and a 7.41 kHz repetition rate. The repetition rate and pulse width of the mode-locked pulses within the Q-switched envelope were 16.9 MHz and ∼910 ps respectively. The multimode QML fiber laser can be turned from 1561.8 nm to 1575.1 nm owing to the multimode interference and the fiber birefringence filtering effect. The QML pulses with dual-wavelength and three-wavelength were also observed by manipulating the polarization controllers and increasing the pump power. The experimental results showed that multimode QML pulses can be achieved with a short FM-EDF at a lower pump power in an all-fiber multimode cavity. The generated low threshold and tunable QML multimode fiber laser has potential application in measuring and mode-division multiplexed system.

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Section: Multimode Qml Operationmentioning

confidence: 99%

All-fiber low threshold tunable multimode Q-switched mode locked fiber laser using a few mode Er-doped fiber

Fan¹,

Zhang²,

Ning³

et al. 2023

Laser Phys.

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“…The CSE method [20] is based on the conjugate symmetric extension property [22]. The method starts from a block mode matrix that is compiled for several modes ψ m .…”

Section: Conjugate Symmetric Extensionmentioning

confidence: 99%

Accuracy of Holographic Real-Time Mode Decomposition Methods Used for Multimode Fiber Laser Emission

Kharenko,

Revyakin,

Gervaziev

et al. 2023

Photonics

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Mode decomposition is a powerful tool for analyzing the modal content of optical multimode radiation. There are several basic principles on which this tool can be implemented, including near-field intensity analysis, machine learning, and spatial correlation filtering (SCF). The latter is meant to be applied to a spatial light modulator and allows one to obtain information on the mode amplitudes and phases of temporally stable beams by only analyzing experimental data. As a matter of fact, techniques based on SCF have already been successfully used in several studies, e.g., for investigating the Kerr beam self-cleaning effect and determining the modal content of Raman fiber lasers. Still, such techniques have a major drawback, i.e., they require acquisition times as long as several minutes, thus being unfit for the investigation of fast mode distribution dynamics. In this paper, we numerically study three types of digital holograms, which permits us to determine, at the same time, the parameters of a set of modes of multimode beams. Because all modes are simultaneously characterized, the processing speed of these real-time mode decomposition methods in experimental realizations will be limited only by the acquisition rate of imaging devices, e.g., state-of-the-art CCD camera performance may provide decomposing rates above 1 kHz. Here, we compare the accuracy of conjugate symmetric extension (CSE), double-phase holograms (DPH), and phase correlation filtering (PCF) methods in retrieving the mode amplitudes of optical beams composed of either three, six, or ten modes. In order to provide a statistical analysis of the outcomes of these three methods, we propose a novel algorithm for the effective enumeration of mode parameters, which covers all possible beam modal compositions. Our results show that the best accuracy is achieved when the amplitude-phase mode distribution associated with multiple frequency PCF techniques is encoded by Jacobi–Anger expansion.

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“…a) b) c) by introducing a spatial frequency shift into a phase mask, which is used to overcome the limitation of phaseonly SLMs, thus encoding both phase and amplitude of a selected mode, 16 or for the parallel measurement of several modes. 10,13 However, the problem is that the position of the capturing point is hard to determine in an experiment, especially in the case of speckled beams. The difficulty is worsened by the high sensitivity of the decomposition results with respect to any positioning error.…”

Section: Point Of Interestmentioning

confidence: 99%

“…In addition, multiple amplitudes can be measured in parallel from one shot. 10 In this work, we propose and apply the MD with phase-only SLM digital holography generation to the study of the Kerr beam self-cleaning effect. 11 The impact of the phase-mask size, and of the true meaning point search procedure are among the several crucial factors that affect the accuracy of the MD procedure, and they will be discussed in details in our presentation.…”

Section: Introductionmentioning

confidence: 99%

Mode decomposition of Kerr self-cleaned beams by phase only SLM

Kharenko

Gervaziev

Zhdanov

et al. 2021

Real-Time Measurements, Rogue Phenomena, and Single-Shot Applications VI

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Graded-index multimode optical fibers have recently attracted a renewed attention, thanks to the discovery of new nonlinear effects, such as Kerr beam self-cleaning. In essence, Kerr self-cleaning involves a flow of the propagating beam energy into the fundamental mode of the fiber, accompanied by a redistribution of the remaining energy among high-order modes. Increasing the fundamental mode energy leads to a significant improvement of the output beam quality. A standard method to determine beam quality is to measure the M 2 parameter. However, since self-cleaning involves the nonlinear redistribution of energy among a large number of fiber modes, measuring a single beam quality parameter is not sufficient to characterize the effect. A properly informative approach requires performing the mode decomposition of the output beam. Mode decomposition permits to evaluate the energy distribution among all of the excited fiber modes, which enables investigations of nonlinear mode coupling processes at a qualitatively new level. In this work, we demonstrate an efficiency mode decomposition method based on holography, which is suitable for analyzing the self-cleaning effect. In a theoretical study, we describe the solution of the mode decomposition problem for the modes of the gradedindex multimode fiber. In an experimental investigation, we demonstrate the decomposition of both low-power (speckled) and self-cleaned beams, involving more than 80 modes.

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Parallel measurement of multiple linear polarization modes in few-mode optical fibers using spatial light modulators

Cited by 4 publications

References 23 publications

All-fiber low threshold tunable multimode Q-switched mode locked fiber laser using a few mode Er-doped fiber

All-fiber low threshold tunable multimode Q-switched mode locked fiber laser using a few mode Er-doped fiber

Accuracy of Holographic Real-Time Mode Decomposition Methods Used for Multimode Fiber Laser Emission

Mode decomposition of Kerr self-cleaned beams by phase only SLM

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