Selective femtosecond laser structuring of dielectric thin films with different band gaps: a time-resolved study of ablation mechanisms

Rapp, Stephan; Schmidt, Michael; Huber, Heinz P.

doi:10.1007/s00339-016-0571-0

Cited by 14 publications

(7 citation statements)

References 51 publications

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“…According to previous studies, it was discovered that the increasing melting and vaporization of the surface silicon led to the removal of the bulging silica layer [ 47 , 48 , 49 , 50 , 51 , 52 ], which was suspected to result in a decrease in the equivalent refractive index of the cladding and the effective refractive index of the waveguide modes, and then the RNWL blueshift occurred. Partial removal of the cladding after the strong post-processing trimming was observed during the experiments, consistent with the previous reports.…”

Section: Resultsmentioning

confidence: 99%

Post-Processing Trimming of Silicon Photonic Devices Using Femtosecond Laser

Shang

Zheng

et al. 2023

Nanomaterials

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Fabrication errors inevitably occur in device manufacturing owing to the limited processing accuracy of commercial silicon photonic processes. For silicon photonic devices, which are mostly processing-sensitive, their performances usually deteriorate significantly. This remains an unsolved issue for mass production, particularly for passive devices, because they cannot be adjusted once fixed in processes. This study presents a post-processing trimming method to compensate for fabrication errors by changing the cladding equivalent refractive indices of devices with femtosecond lasers. The experimental results show that the resonant wavelengths of micro-ring resonators can be regularly shifted within their free spectral range via tuning the illuminating area, focusing position, emitting power, and scanning speed of the trimming femtosecond laser with an acceptable loss increase. These experiments, as well as the trimming experiments in improving the phase balance of Mach-Zehnder interferometer switches, indicate that the femtosecond laser trimming method is an effective and fast method for silicon photonic devices.

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Section: Resultsmentioning

confidence: 99%

Post-Processing Trimming of Silicon Photonic Devices Using Femtosecond Laser

Shang

Zheng

et al. 2023

Nanomaterials

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“…It was initially determined by measuring the autocorrelation of the two beams on the BBO crystal and then accurately determined by measuring the reflectivity change induced by laser-excited e-h plasma. The maximum overlap of pump and probe pulse was achieved when the reflectivity change reaches half of the maxima [28].…”

Section: Pump-probe Imaging Systemmentioning

confidence: 99%

“…Two types of imaging geometries have been used for pump-probe imaging. The front-view imaging geometry was mainly used to obtain reflectance and structuring information, with the angle between pump and probe pulses ranging from 0 • to ~70 • [8][9][10]16,17,[21][22][23][24][25][26][27][28]. The side-view imaging geometry (or shadowgraph) was primarily used to investigate laser-induced material ejection and expansion, for which the angle between pump and probe beam is 90 • [13,27,29].…”

Section: Introductionmentioning

confidence: 99%

Femtosecond-Laser-Ablation Dynamics in Silicon Revealed by Transient Reflectivity Change

et al. 2021

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The dynamics of ablation in monocrystalline silicon, from electron-hole plasma generation to material expansion, upon irradiation by a single femtosecond laser pulse (1030 nm, 300 fs pulse duration) at a wide range of fluences is investigated using a time-resolved microscopy technique. The reflectivity evolution obtained from dynamic images in combination with a theoretical Drude model and a Two-Temperature model provides new insights on material excitation and ablation process. For all fluences, the reflectivity increased to a temporary stable state after hundreds of femtoseconds. This behavior was predicted using a temperature-dependent refractive index in the Drude model. The increase in velocity of plasma generation with increasing fluence was theoretically predicted by the Two-Temperature model. Two ablation regimes at high fluences (>0.86 J/cm2) were identified through the measured transient reflectivity and ablation crater profile. The simulation shows that the fluence triggering the second ablation regime produces a boiling temperature (silicon, 2628 K).

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“…In this way, growth phenomenon relies on shot-to-shot delamination. This is based on the fact that for dielectric layers, without going into details of the physical mechanism for material removal, there is a well-defined threshold for delamination in the sub-picosecond regime and that delaminated structures exhibit clean edges [23,24]. Since growth experiments were carried out at fluences close to the LIDT of the mirror, deep damage generations were avoided.…”

Section: Principle Of the Modelmentioning

confidence: 99%

Sub-picosecond laser damage growth on high reflective coatings for high power applications

et al. 2017

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Growth of laser damage on High Reflection (HR) thin film coatings is investigated at the wavelength of 1.030µm in the sub-picosecond regime. An experimental laser damage setup in a pump / probe configuration is used to study the growth behavior of engineered damage sites as well as laser damage sites. Results demonstrate that engineered sites and laser damage sites grow identically which indicates that the growth phenomenon is intrinsic to materials and stack design. In order to analyze the experimental results, we have developed a numerical model to simulate growth. Using FEM simulations, we demonstrate that growth is governed by the evolution of the electric field distribution in the mirror stack under the successive laser shots, which is supported by time-resolved observations of damage growth events. Eventually the results are compared to laser damage observations made on of full scale PETAL mirrors, which fully support the approach.

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Selective femtosecond laser structuring of dielectric thin films with different band gaps: a time-resolved study of ablation mechanisms

Cited by 14 publications

References 51 publications

Post-Processing Trimming of Silicon Photonic Devices Using Femtosecond Laser

Post-Processing Trimming of Silicon Photonic Devices Using Femtosecond Laser

Femtosecond-Laser-Ablation Dynamics in Silicon Revealed by Transient Reflectivity Change

Sub-picosecond laser damage growth on high reflective coatings for high power applications

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