Continuously linewidth tunable, polarisation maintaining, narrow linewidth fiber laser

Vikram, B. S.; Choudhury, Vishal; Prakash, Roopa; Aparanji, Santosh; Supradeepa, V. R.

doi:10.1117/12.2510431

Cited by 5 publications

(10 citation statements)

References 7 publications

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“…IIIA, which determines the transfer function h(VN) in ( 8); then measuring the vσ of the noise voltage applied to the last amplifier, which determine vn(t) and therefore its PDF p(vn). h -1 (VN) and p(vn) are then used in (8) to compute P(VN), which is inserted in (7) to obtain the carrier suppression. .56, has the shape of a distorted U, distorted in the sense that its bottom right is pulled toward larger Vsat values.…”

Section: (B)mentioning

confidence: 99%

“…Because the degree of incoherence is proportional to the optical bandwidth, bandwidths of GHz [4], [6], [8], [9] or THz [1]- [3] are often required. Most applications meet this goal by using a pulsed laser or a continuous-wave superfluorescent fiber source (SFS).…”

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confidence: 99%

“…As the modulation amplitude is increased, the power in the sidebands is further redistributed into higher-JLT-27020-2020 order sidebands, and sidebands convolve with each other: the optical spectrum therefore smoothes out into a Gaussian shape with a broad bandwidth independent of the original laser linewidth. This method has produced bandwidths ranging from ~1.5 GHz [9] to ~10 GHz [8] and 42 GHz [10]. Only a small fraction fc (~10 -4 ) of residual carrier remains [11].…”

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confidence: 99%

“…This superb precision is achieved by probing the FOG with incoherent light, which significantly reduces the noise and drift arising from spurious interference from light backscattered [5], [6] or polarization-coupled [7] along the FOG's fiber coil. Stimulated Brillouin scattering, which can limit power scaling of fiber lasers, can also be mitigated by externally modulating the phase of the laser with noise to reduce its coherence [8], [9].…”

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confidence: 99%

“…Recently, the bandwidth of a laser has been broadened by sending its output through an electro-optic phase modulator (EOM) driven by broadband RF noise [8], [10], [11]. For weak modulation, some of the carrier power is redistributed into symmetric sidebands whose frequency spectra mirror the RF frequency spectrum.…”

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confidence: 99%

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Optimizing Coherence Suppression in a Laser Broadened by Phase Modulation With Noise

Wheeler

Chamoun

Digonnet

2021

J. Lightwave Technol.

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Phase noise can be modulated onto the output of a laser with an electro-optic phase modulator (EOM) to create a highly incoherent broadened source with low intensity noise. This technique leaves a small but finite fraction of the coherent carrier power that can be highly detrimental in applications requiring incoherent light. This paper shows that the carrier suppression in a laser broadened by this technique can be calculated for an arbitrary noise probability density function. The carrier suppression can be varied experimentally by adjusting the noise voltage standard deviation Gvσ and saturation voltage Vsat of the amplifier that amplifies the noise source that drives the EOM. Simulations show that suppressions better than -30 dB are attainable for reasonable tolerances in Gvσ, for example an EOM with a Vπ of 4.7 V, a Vsat of 6.3 V, and Gvσ/Vπ = 0.73 ± 0.03. Even greater tolerances can be achieved with a higher Vsat (21 V), lower Vp (3.5 V), and Gvσ/Vπ ≈ 3.2 ± 2.3. This model aids in selecting these parameters such that the carrier suppression is resilient to fluctuations in these voltages due to temperature variations and aging of the components. The model predictions are validated by testing a fiber optic gyroscope interrogated with a broadened laser for various Gvσ and Vsat and inferring the carrier suppression from its measured noise. A -44-dB carrier suppression was observed for a nonlinear amplifier with Gvσ = 3.43 V, Vsat = 6.3 V, and an EOM with Vπ = 4.7 V, in agreement with predictions.

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Section: (B)mentioning

confidence: 99%

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confidence: 99%

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confidence: 99%

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confidence: 99%

mentioning

confidence: 99%

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Optimizing Coherence Suppression in a Laser Broadened by Phase Modulation With Noise

Wheeler

Chamoun

Digonnet

2021

J. Lightwave Technol.

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Widely linewidth tunable lasers through cascaded four-wave mixing based phase modulation amplification

Vikram

Prakash

Supradeepa

2021

J. Opt.

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We demonstrate wide-range linewidth-tuning of a narrow-linewidth laser in the C-band up to 40 GHz through cascaded four-wave mixing (CFWM) based phase modulation amplification. Stimulated Brillouin scattering (SBS) severely limits the power scaling of narrow-linewidth lasers. Continuous tuning of the linewidth or temporal coherence of the laser to mitigate SBS is conventionally achieved through external phase modulation with white noise or other RF waveforms. However, the range of linewidth tuning is limited by the bandwidth and power of the electro-optic modulator. We overcome this through the use of FWM as a linewidth multiplier. To achieve linewidth multiplication, two tunable pumps line-broadened in electro-optic phase modulators with white noise are power scaled and propagated through highly nonlinear fiber. We achieve linewidth tuning up to ∼4 GHz using control of the noise waveform, while CFWM achieves a 10× multiplication of linewidth up to 40 GHz at a fixed wavelength. Linewidth tuning can be further scaled through power scaling or cascading multiple nonlinear stages. The proposed technique would be useful in nonlinearity control in narrow-linewidth laser amplifiers, high-resolution optical imaging, LIDAR, and infrared spectroscopy.

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Visible light flashes induced by pulsed stimulated Brillouin scattering in narrow-linewidth, high-power, near-IR fiber lasers

Choudhury

Aparanji

Prakash

et al. 2021

J. Opt.

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We report an interesting observation of visible light flashes indicating pulsing events in Near Infrared fiber laser systems. Using a narrow-linewidth, continuous-wave (CW) fiber laser operating at 1064 nm, we observed visible flashes composed of faint, red, orange, yellow and green colors. Concurrently with the visible flashes, the spectra in the backward direction showed different Raman Stokes orders of 1064 nm for a silica medium. We attribute this form of visible light generation to Cherenkov-type phase-matched harmonic generation in optical fibers enabled by high-peak-power parasitic pulses. These pulses are attributed to the onset of stimulated Brillouin scattering. The harmonics of different Raman Stokes orders of the pulses are responsible for the different visible colors observed. This effect is potentially observable in any laser system with a high optical power with a CW, quasi-CW or pulsed form.

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Continuously linewidth tunable, polarisation maintaining, narrow linewidth fiber laser

Cited by 5 publications

References 7 publications

Optimizing Coherence Suppression in a Laser Broadened by Phase Modulation With Noise

Optimizing Coherence Suppression in a Laser Broadened by Phase Modulation With Noise

Widely linewidth tunable lasers through cascaded four-wave mixing based phase modulation amplification

Visible light flashes induced by pulsed stimulated Brillouin scattering in narrow-linewidth, high-power, near-IR fiber lasers

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