Analysis of Output Pulse Characteristics in $Q$-Switched Yb-Doped Fiber Laser

Upadhyaya, B.N.; Kumar, Abhay; Chakravarty, U.; Oak, S. M.; Shenoy, M. R.; Thyagarajan, K.

doi:10.1109/jqe.2011.2114639

Cited by 11 publications

(12 citation statements)

References 16 publications

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“…For optimal operation, maximum energy should be extracted from the gain medium in a single pulse per modulation cycle, i.e. avoiding the generation of satellite pulses ('multi-pulsing'), which depend critically on the modulation parameters [19]. Experimentally, we found that if the modulator is on for too short a time within each cycle, then lasing is suppressed, but if the on-time is too long (i.e.…”

Section: Resultsmentioning

confidence: 84%

Q-switched Dy:ZBLAN fiber lasers beyond 3 μm: comparison of pulse generation using acousto-optic modulation and inkjet-printed black phosphorus

Woodward¹,

Majewski²,

Macadam³

et al. 2019

Opt. Express

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We report high-energy mid-infrared pulse generation by Q-switching of dysprosiumdoped fiber lasers for the first time. Two different modulation techniques are demonstrated. Firstly, using active acousto-optic modulation, pulses are produced with up to 12 µJ energy and durations as short as 270 ns, with variable repetition rates from 100 Hz to 20 kHz and central wavelengths tunable from 2.97 to 3.23 µm. Experiments are supported by numerical modeling, identifying routes for improved pulse energies and to avoid multi-pulsing by careful choice of modulator parameters. Secondly, we demonstrate passive Q-switching by fabricating an inkjet-printed black phosphorus saturable absorber, simplifying the cavity and generating 1.0 µJ pulses with 740 ns duration. The performance and relative merits of each modulation approach are then critically discussed. These demonstrations highlight the potential of dysprosium as a versatile gain medium for high-performance pulsed sources beyond 3 µm.

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Section: Resultsmentioning

confidence: 84%

Q-switched Dy:ZBLAN fiber lasers beyond 3 μm: comparison of pulse generation using acousto-optic modulation and inkjet-printed black phosphorus

Woodward¹,

Majewski²,

Macadam³

et al. 2019

Opt. Express

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“…[ 3–5 ] One of the undesired phenomena in an AQS‐FL is the multi‐peak phenomenon (MPP), shown in Figure 1 from our rigorous numerical simulation results, which can be described by the system dynamics and the impact of SBS. [ 3,6 ] Note that MPP occurs when the modulator rise time is smaller than the cavity round trip time and in a less serious form shows itself as a stepwise temporal profile as is explained and experimentally shown in refs. [7, 8].…”

Section: Introductionmentioning

confidence: 92%

“…In Section 1, we introduced the split pulse generation and MPP due to system dynamics and the situation would be more complicated under the effects of nonlinear scattering phenomena such as SBS and SRS [ 6,16,17 ] that can completely distort or split the output pulses in AQS‐FLs. Shortening the fiber length and choosing a larger fiber diameter are the common methods for mitigating the above nonlinear effects, [ 15 ] however for single mode operation and producing sufficient pulse energy, two contradictory conditions must be met; the fiber core diameter cannot be very large for achieving a single mode operation and the fiber length is required to be above a minimum to provide enough ions and produce the desired pulse energy.…”

Section: Theoretical Backgroundmentioning

confidence: 99%

Suppression of the Stimulated Brillouin and Raman Scattering in Actively Q‐switched Fiber Lasers through Temporal Pulse Shaping

et al. 2021

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Despite the wide range of applications and versatility, actively Q‐switched fiber lasers (AQS‐FLs) suffer from the multi‐peak phenomenon or stepwise pulse generation under certain conditions. As such, the advantage of the stepwise tendency in AQS‐FL to modify the pulse shape and create a temporal profile that minimizes the power of stimulated Brillouin scattering (SBS) and stimulated Raman scattering (SRS) Stokes components is taken. Accordingly a multi‐objective genetic algorithm (GA) and a Monte‐Carlo method is developed to solve the improved model for SBS. Additionally, the suppression of SRS is predicted and examined successfully. The proposed method is deployed for the simulation of the 5 and 10 kW peak and 10 ns wide pulses on a 4 m long, single‐mode, ytterbium‐doped double clad fiber under the narrow linewidth of 0.05 nm with promising suppression of SBS and SRS effects. To the best of the authors' knowledge this is the first time that such a pulse‐shaping strategy is demonstrated for the SBS or SRS suppression. Furthermore reaching a 10 kW peak on single mode fibers was previously only possible via custom made fibers. Our novel method offers the possibility of optimizing and improving the utilization of different fiber types in AQS‐FL systems.

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“…However, AQS includes a few more challenges such as the generation of multi-peak or separated output pulses with unwanted and hardly predictable overall shapes. This behavior of AQS has been referred frequently as the multi-peak phenomenon (MPP) in the literature [4]- [7]. Wang et al in [4] explain the MPP using perturbation concept.…”

Section: Introductionmentioning

confidence: 99%

“…Wang et al in [4] explain the MPP using perturbation concept. Upadhyaya et al in [7] introduce the Brillouin scattering as a major contributing factor to the MPP generation. Barmenkov et al experimentally explored the repetitive regimes of AQS in the context of chaos theory [1].…”

Section: Introductionmentioning

confidence: 99%

Optimal Pulse-Shaping in Actively Q-Switched Ytterbium-Doped Fiber Lasers

2020

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In an actively Q-switched fiber laser (AQS-FL) a type of acousto-optic modulator (AOM) or (potentially) electro-optic modulator (EOM) controls the generation of output nanosecond wide pulses. An integrated Gaussian pulse shape is desirable in many applications such as material processing, microfabrication, ultrasound generation, gold photothermal therapy, etc. However, because of the system dynamics, generation of perfect Gaussian pulse shapes is not guaranteed in an AQS-FL, additionally designing the AQS-FL for a desired pulse peak and duration is an inverse problem which needs cumbersome trialerror efforts. We have developed a framework consisting of a rigorous FDM method plus a dedicated and innovative multi-objective genetic algorithm (GA) which assists the designer in achieving the desired Gaussian pulses within a reasonable time frame. The developed GA evolves the timing parameters of modulator plus the pump power and fiber length until the suitable goal is reached. To demonstrate the flexibility and design feasibility of our GA, three different single pulse and pulse train generation scenarios on a 7.5 m long Ytterbium-doped double clad fiber (YD-DCF) are examined to achieve the Gaussian,150 Wand 200 W peak power, 250 ns and 300 ns width pulses. To the best of our knowledge, it is the first implementation of an intelligent algorithm for optimizing the output pulse of an AQS-FL. It is worth noting that depending on the fiber host material and modulator specifications, much higher peak powers and different pulse durations are feasible, furthermore in case of utilizing the AOM, the pertaining limitations and feasibility are considered.

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Analysis of Output Pulse Characteristics in $Q$-Switched Yb-Doped Fiber Laser

Cited by 11 publications

References 16 publications

Q-switched Dy:ZBLAN fiber lasers beyond 3 μm: comparison of pulse generation using acousto-optic modulation and inkjet-printed black phosphorus

Q-switched Dy:ZBLAN fiber lasers beyond 3 μm: comparison of pulse generation using acousto-optic modulation and inkjet-printed black phosphorus

Suppression of the Stimulated Brillouin and Raman Scattering in Actively Q‐switched Fiber Lasers through Temporal Pulse Shaping

Optimal Pulse-Shaping in Actively Q-Switched Ytterbium-Doped Fiber Lasers

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