Processes Resulting from the Intensity-Dependent Refractive Index

Boyd, Robert W.

doi:10.1016/b978-0-12-369470-6.00007-1

Cited by 16 publications

(2 citation statements)

References 40 publications

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“…The Kerr nonlinearity in diamond at infrared wavelengths (n 2 = 4.2 × 10 −20 m 2 / W [57]) is comparable to other optical crystals. The critical power for self-focusing [66] is approximately 1.6 MW for linearly polarized light at 1064 nm.…”

Section: Table I Thermal and Nonlinear Effects In End-pumped Lasersmentioning

confidence: 99%

High Power Diamond Raman Lasers

Williams

Kitzler

Bai

et al. 2018

IEEE J. Select. Topics Quantum Electron.

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Laser gain materials possessing high thermal conductivity and robust mechanical properties are key prerequisites for high power lasers. We show that diamond, when configured as a Raman laser, enables access to these and other extreme properties, providing an important new route to high power and high brightness beam generation. Recent achievements in pulsed and continuous wave oscillators, beam combining amplifiers, and single longitudinal mode oscillators are summarized, along with wavelength extension of these concepts through adaption to other pumps, use of Raman cascading, and intracavity harmonic generation. To date, diamond laser powers have attained 750 W with efficiency and beam quality so far unperturbed by nonlinear or thermally induced side-effects. Large factor brightness enhancement of low coherence inputs is demonstrated using multiple pump beams (via Raman beam combination) or highly multimode pumps for oscillator and amplifier configurations. Future directions for direct diode pumping, and for realizing extraordinary power and power density through reduced temperature operation and isotopically enriched diamond, are also discussed. Our results indicate that diamond is emerging as a generic high-power laser technology with advantages in terms of brightness (high average power and high beam quality) and wavelength range.

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Section: Table I Thermal and Nonlinear Effects In End-pumped Lasersmentioning

confidence: 99%

High Power Diamond Raman Lasers

Williams

Kitzler

Bai

et al. 2018

IEEE J. Select. Topics Quantum Electron.

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“…For this purpose, the simple diatomic molecule was selected as absorbant for LIGS thermometry due to its high abundance in air-fed combustion processes. The excitation of with high intensity ultrashort laser pulses might result in irradiances in the probe volume high enough for ionization, laser trapping 23 , and “lasing” actions 24 . However, in the present study, the pulse energy was kept below the ionization threshold in order to avoid additional uncertainties in the measurement results.…”

Section: Introductionmentioning

confidence: 99%

Laser-induced thermal grating spectroscopy based on femtosecond laser multi-photon absorption

Ruchkina

Hot

Ding

et al. 2021

Sci Rep

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Laser-induced grating spectroscopy (LIGS) is for the first time explored in a configuration based on the crossing of two focused femtosecond (fs) laser pulses (800-nm wavelength) and a focused continuous-wave (cw) laser beam (532-nm wavelength). A thermal grating was formed by multi-photon absorption of the fs-laser pulses by $$\hbox {N}_{{2}}$$ N 2 with a pulse energy around 700 $$\upmu $$ μ J ($$\sim $$ ∼ 45 TW/$$\hbox {cm}^{2}$$ cm 2 ). The feasibility of this LIGS configuration was investigated for thermometry in heated nitrogen gas flows. The temperature was varied from room temperature up to 750 K, producing strong single-shot LIGS signals. A model based on the solution of the linearized hydrodynamic equations was used to extract temperature information from single-shot experimental data, and the results show excellent agreement with the thermocouple measurements. Furthermore, the fluorescence produced by the fs-laser pulses was investigated. This study indicates an 8-photon absorption pathway for $$\hbox {N}_{{2}}$$ N 2 in order to reach the $$\hbox {B}^{3}\Pi _{g}$$ B 3 Π g state from the ground state, and 8 + 5 photon excitation to reach the $$\hbox {B}^{2}\Sigma _{u}^{+}$$ B 2 Σ u + state of the $$\hbox {N}_{2}^{+}$$ N 2 + ion. At pulse energies higher than 1 mJ, the LIGS signal was disturbed due to the generation of plasma. Additionally, measurements in argon gas and air were performed, where the LIGS signal for argon shows lower intensity compared to air and $$\hbox {N}_{{2}}$$ N 2 .

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Transverse and axial resolution of femtosecond laser ablation

Wang

Grooms

Chung

2022

Journal of Biophotonics

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Femtosecond lasers are capable of precise ablation that produces surgical dissections in vivo. The transverse and axial resolutions of the laser damage inside the bulk are important parameters of ablation. The transverse resolution is routinely quantified; but the axial resolution is more difficult to measure and is less commonly performed. Using a 1040‐nm, 400‐fs pulsed laser, and a 1.4‐NA objective, we performed ablation inside agarose and glass, producing clear, and persistent damage spots. Near the ablation threshold of both media, we found that the axial resolution is similar to the transverse resolution. We also ablated neuron cell bodies and fibers in Caenorhabditis elegans and demonstrate submicrometer resolution in both the transverse and axial directions, consistent with our results in agarose and glass. Using simple yet rigorous methods, we define the resolution of laser ablation in transparent media along all directions.

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Processes Resulting from the Intensity-Dependent Refractive Index

Cited by 16 publications

References 40 publications

High Power Diamond Raman Lasers

High Power Diamond Raman Lasers

Laser-induced thermal grating spectroscopy based on femtosecond laser multi-photon absorption

Transverse and axial resolution of femtosecond laser ablation

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