Henry’s fiber Regen

 

 

Single-mode regenerative amplification in multimode fiber

Henry Haig, Nicholas Bender, Yishai Eisenberg,  Frank Wise, “Single-mode regenerative amplification in multimode fiber,” Optica 10, 1417-1420 (2023)

The peak power performance of ultrafast fiber lasers scales with fiber mode area, but large fibers host multiple modes that are difficult to control. We demonstrate a technique for single-mode operation of highly multimode fiber based on regenerative amplification. This results in a short-pulse fiber source with, to our knowledge, an unprecedented combination of features: high gain (>55 dB) with negligible amplified spontaneous emission, high pulse energy (>50 µJ), good beam quality (𝑀2≤1.3), and transform-limited (300 fs) pulses from a single amplification stage. We discuss peak intensity scaling to much higher levels and other opportunities for short-pulse generation in regenerative fiber amplifiers.

Nick_Optica2023

Spectral speckle customization

Nicholas Bender, Henry Haig, Demetrios N. Christodoulides, and Frank W. Wise, “Spectral speckle customization,” Optica 10, 1260-1268 (2023)

Speckle patterns are used in a broad range of applications including microscopy, imaging, and light–matter interactions. Tailoring speckles’ statistics can dramatically enhance their performance in applications. We present an experimental technique for customizing the spatio-spectral speckled intensity statistics of optical pulses at the output of a complex medium (a disordered multimode fiber) by controlling the spatial profile of the input light. We demonstrate that it is possible to create ensembles of independent speckle patterns with arbitrary statistics at a single wavelength, simultaneously at multiple decorrelated wavelengths, and even tailored statistics across an entire pulse spectrum.

Yuhang Wu_AnomalousBC

Beam self-cleaning of femtosecond pulses in the anomalous dispersion regime

Wu, H. Pourbeyram, D. N. Christodoulides, and F. W. Wise, “Weak beam self-cleaning of femtosecond pulses in the anomalous dispersion regime,” Opt. Lett. 46, 3312–3315 (2021).

Kerr beam cleaning in graded-index multimode fiber has been investigated in experiments with sub-nanosecond pulses and in experiments with femtosecond pulses at wavelengths where the dispersion is normal.  We report a theoretical and experimental study of this effect with femtosecond pulses and anomalous dispersion.  In this regime, beam-cleaning is observed experimentally.  Beyond the spatial dynamics, with the increase of input pulse energy, there is a strong temporal self-compression of the pulse from 500 fs down to around 30 fs (a factor of 17). Numerical simulations exhibit the qualitative trends of the experiments. Our study provides a way to enhance beam quality and temporal peak power at the same time in graded-index multimode fiber and the anomalous dispersion regime.

Henry_MMMamyshev

 

Multimode Mamyshev oscillator

Henry Haig, Pavel Sidorenko, Anirban Dhar, Nilotpal Choudhury, Ranjan Sen, Demetrios Christodoulides, and Frank Wise, “Multimode Mamyshev oscillator,” Opt. Lett. 47, 46-49 (2022)

Regular mode-locked lasers make short light pulses by synchronization or “locking” of many longitudinal cavity modes. It was recently shown that the transverse modes of a cavity can also be synchronized in a similar— but more general— form of mode-locking known as “spatiotemporal mode-locking” (STML). These lasers make ultrafast pulses that have spatial structure due to the many transverse modes involved. Understanding of this phenomenally complex phenomenon is limited: STML has so far been demonstrated a handful of times in relatively similar types of multimode fiber lasers. In this project, we study STML in a very different type of cavity architecture— the Mamyshev oscillator. The laser supports a vast array of mode-locked states. Learning to control these states in a meaningful way is a long-term goal which might enable gigawatt-class fiber lasers, or fiber lasers that generate purposefully-structured light for applications.

Spatiotemporal mode-locking in multimode fiber lasers

Spatiotemporal mode-locking in multimode fiber lasers

L.G. Wright, D.N. Christodoulides, and F.W. Wise (2017) “Spatiotemporal mode-locking in multimode fiber lasers,” Science 358 (6359), 94-97.

Unlike a conventional single-mode, ‘one-dimensional’ laser, the frequencies of a multimode, multidimensional laser are ordinarily very complicated (figure below, top left, where different colors correspond to different spatial modes). However, we showed that, for a properly designed laser (bottom), the laser’s frequencies would adjust automatically into an organized, synchronized pattern (figure top right), corresponding to the emission of a 3D, multimode laser pulse at regular intervals. Pulses from this laser might eventually allow very sophisticated light-matter interactions, especially with complex molecules (different modes of the laser may interact with different ‘modes’, specific transitions, of molecules or other matter). We have some moderately crazy ideas to realize PW or even EW (exawatt) lasers with this approach.

Spatiotemporal dynamics of multimode optical solitons

Spatiotemporal dynamics of multimode optical solitons

L. G. Wright, W. H. Renninger, D. N. Christodoulides, and F. W. Wise. “Spatiotemporal dynamics of multimode optical solitons”. Opt. Express 22, 3492-3506 (2015).

We launch pulses into multimode fiber, exciting multiple spatial modes. We show how nonlinear interactions between the modes give rise to a multimode soliton. A multimode soliton is a non-dispersing wavepacket that contains several distinct spatial mode components, and propagates through the fiber without changing its shape due to a balance between nonlinear and linear effects. We observe spatiotemporal soliton fission – the disintegration of an optical pulse into distinct multimode soliton components with different spatiotemporal properties. Lastly, we observe the effect of stimulated Raman scattering on multimode solitons. This causes them to shift to longer wavelengths, while maintaining their multimode soliton characteristics.

Ultrabroadband Dispersive Radiation by Spatiotemporal Oscillation of Multimode Waves

Ultrabroadband Dispersive Radiation by Spatiotemporal Oscillation of Multimode Waves

L. G. Wright, S. Wabnitz, D. N. Christodoulides, F. W. Wise “Ultrabroadband Dispersive Radiation by Spatiotemporal Oscillation of Multimode Waves ” Phys. Rev. Lett. 115, 223902 (2015).

We show that intense pulses in multimode fiber oscillate in space and time, and that this creates resonant radiation across the electromagnetic spectrum. This work provides a route to tunable sources of ultrashort pulses from IR to ultraviolet and beyond. Dreaming, this work could lead to a fiber-format alternative to the free-electron laser.