CeFO-Related Publications

@article{Hu2021,

title = {Morphology and waveguiding properties of ultrafast-laser-inscribed type-II waveguides in IG2},

author = {W. Hu and M. Kilinc and W. Gebremichael and C. Dorrer, and J. Qiao},

url = {https://opg.optica.org/ome/fulltext.cfm?uri=ome-12-1-360&id=466364},

year  = {2021},

date = {2021-12-24},

urldate = {2021-12-24},

journal = {Optical Materials Express},

volume = {12},

number = {1},

pages = {360-373},

abstract = {Ultrafast-laser-inscribed type-II waveguides inside the chalcogenide glass IG2 and the morphology of the inscribed tracks are presented for the first time to our knowledge. Self-organized periodic structures induced by the ultrafast laser in the tracks are characterized. The near-infrared waveguiding properties are studied for various pulse energies, durations, repetition rates, and polarization states, as well as different separations between the two written tracks. A propagation loss of ∼ 2.3 dB/cm is demonstrated in a type-II waveguide formed in IG2.},

keywords = {manufacturing, related},

pubstate = {published},

tppubtype = {article}

}

@article{Feng2021,

title = {Femtosecond-Laser-Ablation Dynamics in Silicon Revealed by Transient Reflectivity Change},

author = {T. Feng and G. Chen and H. Han and J. Qiao},

url = {https://www.mdpi.com/2072-666X/13/1/14#

https://centerfreeformoptics.org/wp-content/uploads/2023/02/micromachines-13-00014-v2.pdf},

doi = {https://doi.org/10.3390/mi13010014},

year  = {2021},

date = {2021-12-23},

urldate = {2021-12-23},

journal = {Micromachines},

volume = {13},

number = {1},

abstract = {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).},

keywords = {manufacturing, related},

pubstate = {published},

tppubtype = {article}

}

@article{Horvath_2021a,

title = {Advancing lightweight mirror design: a paradigm shift in mirror preforms by utilizing design for additive manufacturing},

author = {Nicholas Horvath and Matthew Davies},

doi = {https://doi.org/10.1364/AO.410350},

year  = {2021},

date = {2021-01-18},

urldate = {2021-01-18},

journal = {Applied Optics},

volume = {60},

issue = {3},

pages = {681-696},

abstract = {Additive manufacturing is a disruptive technology that can be leveraged by the redesign of components in most engineering fields. Fundamental engineering resources for lightweight mirrors were developed more than 30 years ago with a main design limitation, state of the art manufacturing. Here, we present two design methodologies for the design of lightweight mirrors. The first method utilizes analytical expressions to design a traditional isogrid mirror, which provided the foundation for most lightweight mirrors to date. The second method employs a combination of topology optimization, lattice infill, and analytical estimation to develop an advanced lightweight mirror designed for additive manufacturing. The advanced mirror design outperforms the traditional design for each functional requirement, including a 94% reduction in predicted surface quilting and a higher specific stiffness. The manufacturing of the advanced mirror is only possible with an additive manufacturing process.},

keywords = {CeFO related, manufacturing},

pubstate = {published},

tppubtype = {article}

}

@article{Sahoo2020,

title = {Dynamic pulse propagation modelling for predictive femtosecond-laser-microbonding of transparent materials},

author = {Pankaj K. Sahoo and Tao Feng and Jie Qiao},

doi = {https://doi.org/10.1364/OE.402493},

year  = {2020},

date = {2020-10-02},

urldate = {2020-10-02},

journal = {Opt. Express},

volume = {28},

number = {21},

pages = {31103-31118},

abstract = {A dynamic pulse propagation modeling for femtosecond laser bonding of Borofloat glass is presented. The temperature evolution and internal modifications are predicted by incorporating the nonlinear electron dynamics along with temperature dependent thermal properties. The modelling predicts the spatial and temporal distribution of absorption coefficient and plasma density that gives quantitative estimations of the heat affected zone and weld geometry. The impact of focusing condition on heat affected zone and weld geometry is investigated, which for the first time to our knowledge allows to numerically determine the desired relative position between the geometrical focus of a femtosecond-laser-pulse and the interface of the two substrates to be welded. The prediction of the modelling on the offset distance is applied to weld Borofloat glass plates having optical contact and can be applied to other dielectric solids.},

keywords = {manufacturing, related},

pubstate = {published},

tppubtype = {article}

}

@article{Horvath19-ab,

title = {Grinding of additively manufactured silicon carbide surfaces for optical applications},

author = {Nicholas Horvath and Andrew Honeycutt and Matthew A. Davies},

url = {https://doi.org/10.1016/j.cirp.2020.04.079},

year  = {2020},

date = {2020-05-19},

journal = {CIRP Annals},

volume = {69},

pages = {509-512},

abstract = {Many of the properties of Silicon carbide (SiC) are advantageous for optical applications, such as telescope mirrors and industrial laser systems. However, the base shapes of complex components are costly and difficult to manufacture. Leveraging additive manufacturing, near net complex components are readily processed. Here, we investigate the post processing of additively manufactured SiC (AM SiC) compared to chemical vapor deposited (CVD) SiC. The specific grinding energy for the AM SiC was lower than CVD, however the trends were the same. A specular finish was observed on both materials but the AM SiC finish was limited due to residual porosity.},

keywords = {manufacturing, related},

pubstate = {published},

tppubtype = {article}

}

@article{TAYLOR2019,

title = {Femtosecond laser polishing of germanium},

author = {LAUREN L. TAYLOR, JING XU, MICHAEL POMERANTZ, THOMAS

R. SMITH, JOHN C. LAMBROPOULOS, AND JIE QIAO},

url = {https://doi.org/10.1364/OME.9.004165},

year  = {2019},

date = {2019-10-02},

journal = {Optical Materials Express},

volume = {9},

number = {11},

pages = {4165-4177},

abstract = {Freeform optics can reduce the cost, weight, and size of advanced imaging systems,

but it is challenging to manufacture the complex rotationally asymmetric surfaces to optical

tolerances. To address the need for disruptive, high-precision sub-aperture forming and finishing

techniques for freeform optics, we investigate an alternative, non-contact polishing methodology

using femtosecond lasers, combining modeling, experiments, and demonstrations. Femtosecondlaser-

based polishing of germanium was investigated using an experimentally-validated twotemperature

model of laser/germanium interaction to guide the understanding and selection of

laser parameters to achieve near-nonthermal ablation for polishing and figuring. For the first time

to our knowledge, model-guided femtosecond laser polishing of germanium was successfully

demonstrated, achieving precision material removal while maintaining single-digit nanometer

optical surface quality. The demonstrated femtosecond-laser-based polishing technique lays the

foundation for semiconductor optics polishing/fabrication using femtosecond lasers and opens a

viable path for high-precision, complex sub-aperture optical polishing tasks on various materials.},

keywords = {CeFO manufacturing, CEFO metrology, fabrication, Freeform surfaces, manufacturing, Mid-Spatial Frequency error},

pubstate = {published},

tppubtype = {article}

}

@article{Feng2019,

title = {Pulse-Propagation Modeling and Experiment for Femtosecond-Laser Writing of Waveguide in Nd:YAG},

author = {Tao Feng and Pankaj K. Sahoo and Francisco R. Arteaga-Sierra and Christophe Dorrer and Jie Qiao},

doi = {https://doi.org/10.3390/cryst9080434},

year  = {2019},

date = {2019-08-20},

urldate = {2019-08-20},

journal = {Crystals },

volume = {9},

number = {8},

pages = {434},

abstract = {In this work, unidirectional pulse propagation equation (UPPE) modeling is performed to study the nonlinear laser-mater interaction in silicon and Nd:Y3Al5O12 (Nd:YAG) crystals. The simulation results are validated with reported experimental results for silicon and applied to Nd:YAG crystals with experimental validation. Stress-induced waveguides are written in Nd:YAG crystals using 515 nm, 300 fs pulses at a 1 kHz repetition rate. Waveguides having a mean propagation loss of 0.21 ± 0.06 dB/cm are obtained, which is lower than the previous reported values for Type-II waveguides written in Nd:YAG crystals. The modeling and experimental results consistently show that the modification (waveguide track) depth increases with input energy. A detailed analysis is presented to control the modal properties of the waveguide in the context of UPPE simulation.},

keywords = {CeFO related, manufacturing},

pubstate = {published},

tppubtype = {article}

}

@article{Mishchik2019,

title = {High-efficiency femtosecond ablation of silicon with GHz repetition rate laser source},

author = {Konstantin Mishchik and Guillaume Bonamis and Jie Qiao and John Lopez and Eric Audouard and Eric Mottay and Clemens Hönninger and Inka Manek-Hönninger},

doi = {https://doi.org/10.1364/OL.44.002193},

year  = {2019},

date = {2019-05-01},

urldate = {2019-05-01},

journal = {Opt. Lett.},

volume = {44},

number = {9},

pages = {2193-2196},

abstract = {We report on silicon ablation with a 20 W GHz amplified femtosecond laser source. This novel laser delivers burst energies up to 400 μJ, providing flexible intra-pulse repetition rates of 0.88 or 3.52 GHz, up to 200 pulses with ∼350 fs pulse duration. High-efficiency, high-quality ablation can be achieved through optimally determining the number of pulses, intra-pulse repetition, and average pulse energy within a burst. Due to such optimization, we demonstrate a specific ablation rate of 2.5 mm3∕ min ∕W with a burst containing 200 pulses at 0.88 GHz, which is the highest one reported so far for fs laser ablation, to the best of our knowledge. GHz ablation is sensitive to the selection of laser parameters. We conceptually discuss the contributions of the pulses within a burst to heat-accumulation-based incubation and material ablation.},

keywords = {CeFO related, manufacturing},

pubstate = {published},

tppubtype = {article}

}

@article{LaurenApp18,

title = {Direct binary search for improved beam shaping and optical differentiation wavefront sensing},

author = {C. Dorrer and J. Qiao},

doi = {https://doi.org/10.1364/AO.57.008557},

year  = {2018},

date = {2018-06-01},

urldate = {2018-06-01},

journal = {Applied Optics},

volume = {57},

number = {29},

pages = {8557-8565 },

abstract = {Spatially dithered distributions of binary amplitude pixels are optimized using a full direct binary search, taking into account the experimental configuration for amplitude modulation of coherent waves. This design process is shown to yield a significant reduction of the noise induced by binarization and pixelation over the region of interest. We demonstrate this approach for beam shaping and optical differentiation wavefront sensing, where the region of interest is in an image plane of the pixel distribution, and in the far field of the pixel distribution, respectively. The observed reduction in error compared to a standard error diffusion algorithm is significant for both applications because it improves performance without the tighter fabrication tolerance and cost associated with smaller pixels.},

keywords = {CeFO related, manufacturing, related},

pubstate = {published},

tppubtype = {article}

}

@article{QiaoOMEX18,

title = {Integrating two-temperature and classical heat accumulation models to predict femtosecond laser processing of silicon},

author = {L. L. Taylor and R. E. Scott and J. Qiao },

doi = {https://doi.org/10.1364/OME.8.000648},

year  = {2018},

date = {2018-03-01},

urldate = {2018-03-01},

journal = {Optical Materials Express},

volume = {8},

number = {3},

pages = {648-658},

abstract = {A robust, computationally efficient modeling method describing multi-pulse femtosecond laser-material interaction is required to determine the optimal laser parameters to control and differentiate non-thermal ablation and heat accumulation processes for surface structuring and laser welding applications. We establish a three-dimensional, two-temperature model (TTM) and a heat-accumulation model based on classical heat generation and conduction equations to evaluate their efficacy and efficiency in simulating non-thermal ablation and heat accumulation during multi-pulse femtosecond laser processing of silicon. Only the TTM is capable of accurately predicting the laser fluences required to achieve non-thermal ablation, which is experimentally validated. Both the TTM and the classical heat accumulation model can predict heat accumulation. The TTM can accurately predict heat accumulation, but requires lengthy simulation times on the order of several hours. The classical heat accumulation model consistently predicts heat accumulation with the TTM and is time efficient, but is case specific to interaction parameters, requiring input of an experimentally-determined absorption coefficient. For the first time to our knowledge, an integrated modeling method is devised to accurately and efficiently simulate laser-processing-induced heat accumulation by using the TTM to determine an absorption coefficient to feed back to the heat accumulation model to extend it to the general case. This integrated modeling method enables the accurate prediction of heat accumulation with simulation times on the order of a minute per pulse, defining a path to determine laser parameters to control heat accumulation for specific processing applications.},

keywords = {CeFO related, manufacturing},

pubstate = {published},

tppubtype = {article}

}

@article{Salzman15,

title = {Magnetorheological finishing of chemical-vapor-deposited zinc sulfide via chemically and mechanically modified fluids},

author = {Salzman, S. and H. J. Romanofsky and L. J. Giannechini and S. D. Jacobs and J. C. Lambropoulos},

doi = {https://doi.org/10.1364/AO.55.001481},

year  = {2015},

date = {2015-11-03},

urldate = {2015-11-03},

journal = {Applied Optics},

volume = {55},

number = {6},

pages = {1481},

abstract = {We describe the anisotropy in the material-removal rate (MRR) of the polycrystalline, chemical-vapor–deposited (CVD) zinc sulfide (ZnS). We define the polycrystalline anisotropy via microhardness and chemical erosion tests for four crystallographic orientations of ZnS: (100), (110), (111), and (311). Anisotropy in the MRR was studied under magnetorheological finishing (MRF) conditions. Three chemically and mechanically modified magnetorheological (MR) fluids at pH values of 4, 5, and 6 were used to test the MRR variations among the four single-crystal planes. When polishing the single-crystal planes and the polycrystalline with pH 5 and pH 6 MR fluids, variations were found in the MRR among the four single-crystal planes and surface artifacts were observed on the polycrystalline material. When polishing the single-crystal planes and the polycrystalline with the modified MR fluid at pH 4, however, minimal variation was observed in the MRR among the four orientations and a reduction in surface artifacts was achieved on the polycrystalline material.},

keywords = {manufacturing, related},

pubstate = {published},

tppubtype = {article}

}