Prof. Ephraim Suhir Profile

Prof. Ephraim Suhir

CEO at ERS Co

SPIE Involvement:

Author

Proceedings Article | 22 February 2018 Presentation + Paper

Predicted static fatigue (delayed fracture) lifetime of a fiber optic test specimen: application of analytical modeling technique

E. Suhir, S. Yi

Proceedings Volume 10528, 105280W (2018) https://doi.org/10.1117/12.2280650

KEYWORDS: Humidity, Reliability, Optical fibers, Failure analysis, Fiber optics tests, Data modeling, Silica, Physics, Solid modeling, Statistical modeling

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Proceedings Article | 20 February 2017 Presentation + Paper

Thermal stress in an optical silica fiber embedded (soldered) into silicon

E. Suhir, S. Yi

Proceedings Volume 10108, 101080L (2017) https://doi.org/10.1117/12.2247035

KEYWORDS: Interfaces, Silicon, Silicon photonics, Optical fibers, Thermal modeling, Systems modeling, Glasses, Mathematical modeling, Reliability, Thermography

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Proceedings Article | 16 February 2017 Presentation + Paper

Elastic stability of a dual-coated fiber-optic connector

E. Suhir, S. Yi

Proceedings Volume 10100, 101001K (2017) https://doi.org/10.1117/12.2246969

KEYWORDS: Connectors, Fiber optics, Optical fibers, Coating, Glasses, Optical components, Fiber coatings, Silica, Differential equations, Mechanical engineering

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Proceedings Article | 16 February 2017 Presentation + Paper

Predicted lattice-misfit stresses in a gallium-nitride (GaN) film

E. Suhir, S. Yi

Proceedings Volume 10104, 1010408 (2017) https://doi.org/10.1117/12.2246963

KEYWORDS: Nanolithography, Gallium nitride, Semiconductors, Crystals, Shape memory alloys, Silicon carbide, Supercontinuum generation, Bessel functions, Silicon, Assembly equipment

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Effective, easy-to-use and physically meaningful analytical predictive models are developed for the evaluation the lattice-misfit stresses (LMS) in a semiconductor film grown on a circular substrate (wafer). The two-dimensional (plane-stress) theory-of-elasticity approximation (TEA) is employed. First of all, the interfacial shearing stresses are evaluated. These stresses might lead to the occurrence and growth of dislocations, as well as to possible delaminations (adhesive strength of the assembly) and the elevated stress and strain in the buffering material, if any (cohesive strength of the assembly). Second of all, the normal radial and circumferential (tangential) stresses acting in the film cross-sections are determined. These stresses determine the short- and long-term strength (fracture toughness) of the film material. It is shown that while the normal stresses in the semiconductor film are independent of its thickness, the interfacial shearing stresses increase with an increase in the induced force (not stress!) acting in the film cross-sections, and that this force increases with an increase in the film thickness. This leads, for a thick enough film, to the occurrence, growth and propagation of dislocations. These start at the assembly ends and propagate, when the film thickness increases, inwards the structure. The TEA data are compared with the results obtained using a simplified strength-of-materials approach (SMA). This approach considers, instead of an actual circular assembly, an elongated bi-material rectangular strip of unit width and of finite length equal to the wafer diameter. The analysis, although applicable to any semiconductor crystal growth (SCG) technology is geared in this analysis to the Gallium-Nitride (GaN) technology. The numerical example is carried out for a GaN film grown on a Silicon Carbide (SiC) substrate. It is concluded that the SMA model is acceptable for understanding the physics of the state of stress and for the prediction of the normal stresses acting in the major mid-portion of the assembly. The SMA model underestimates, however, the maximum interfacial shearing stress at the assembly periphery, and, because of the very nature of the SMA, is unable to address the circumferential stress. This stress can be quite high at the circular boundary of the assembly. At the assembly edge the circumferential stress is as high as σθ = (2–ν₁)σ₁, i.e., by the factor of 2–ν₁ higher than the normal stress, σ₁, in the mid-portion of the film. In this formula, ν₁ is Poisson’s ratio of the film material.

Proceedings Article | 3 April 2015 Paper

Analytical (mathematical) predictive modeling in fiber optics structural analysis (FOSA): review and extension

Ephraim Suhir

Proceedings Volume 9368, 93680O (2015) https://doi.org/10.1117/12.2074964

KEYWORDS: Reliability, Coating, Optical fibers, Fiber optics, Fiber coatings, Structured optical fibers, Glasses, Mathematical modeling, Finite element methods, Optoelectronics

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An updated version of the paper with revised references has been published The review part of the paper addresses analytical (mathematical) modeling in structural analysis in fiber optics engineering, mostly fiber optics interconnects, and deals with optical fibers subjected to thermal and/or mechanical loading (stresses) in bending, tension, compression, or to the combinations of such loadings. Attributes and significance of predictive modeling are indicated and discussed. The review is based mostly on the author’s research conducted at Bell Laboratories, Physical Sciences and Engineering Research Division, Murray Hill, NJ, USA, during his tenure with this company, and, to a lesser extent, on his recent work in the field. The addressed structures include, but are not limited to, optical fibers of finite length: bare fibers; jacketed and dual-coated fibers; fibers experiencing thermal loading; fibers soldered into ferrules or adhesively bonded into capillaries; as well as the roles of geometric and material non-linearity; dynamic response to shocks and vibrations; and possible applications of nano-materials in new generations of coating and cladding systems. The extension part is concerned with a novel, fruitful and challenging directionprobabilistic design for reliability (PDfR) of opto-electronic and photonic products, including optical fibers and interconnects. The rationale behind the PDfR concept is that there is no such thing as zero probability of failure, that the difference between a highly reliable product and an insufficiently reliable product is “merely” in the level of the never zero probability of its failure and that when the operational performance of the product is imperative, the ability to predict, quantify, assure and, if possible and appropriate, even specify its reliability is highly desirable. Accordingly, the objective of the PDfR effort is to quantify the likelihood of an operational failure of a material, device or a system, including the field of fiber optics.

Proceedings Article | 13 March 2015 Paper

Ephraim Suhir

Proceedings Volume 9363, 93630P (2015) https://doi.org/10.1117/12.2074963

KEYWORDS: Gallium nitride, Silicon carbide, Diamond, Temperature metrology, Interfaces, Assembly equipment, Thin films, Annealing, Polishing, Lithium

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Simple, easy-to-use and physically meaningful analytical models have been developed for the assessment of the combined effect of the lattice and thermal mismatch on the induced stresses in an elongated bi-material assembly, as well as on the thermal mismatch on the thermal stresses in a tri-material assembly, in which the lattice mismatched stresses are eliminated in one way or another. This could be done, e.g., by using a polished or an etched substrate. The analysis is carried out in application to Gallium Nitride (GaN)-Silicon Carbide (SiC) and GaN-diamond (C) filmsubstrate assemblies. The calculated data are obtained, assuming that no annealing or other stress reduction means is applied. The data agree reasonably well with the reported (available) in-situ measurements. The most important conclusion from the computed data is that even if a reasonably good lattice match takes place (as, e.g., in the case of a GaN film fabricated on a SiC substrate, when the mismatch strain is only about 3%) and, in addition, the temperature change (from the fabrication/growth temperature to the operation temperature) is significant (as high as 1000 ̊C), the thermal stresses are still considerably lower than the lattice-mismatch stresses. Although there are structural and technological means for further reduction of the lattice-mismatch stresses (e.g., by high temperature annealing or by providing one or more buffering layers, or by using patterned or porous substrates), there is still a strong incentive to eliminate completely the lattice mismatch stresses. This seems to be indeed possible, if polished or otherwise flattened (e.g., chemically etched) substrates and sputter deposited GaN film is employed. In such a case only thermal stresses remain, but even these could be reduced, if necessary, by using compliant buffering layers, including layers of variable compliance, or by introducing variable compliance into the properly engineered substrate. In any event, it is expected that strong adhesion could be achieved by using an appropriate fabrication technology, so that no GaN film cracking would be possible, if the film is in tension, or delamination buckling could occur if the film is in compression. The developed models can be used to assess the possibilities and opportunities associated with GaN materials technology.

Proceedings Article | 24 September 2013 Paper

Photovoltaic reliability engineering: quantification testing and probabilistic-design-reliability concept

Ephraim Suhir, Laurent Bechou, Alain Bensoussan, Johann Nicolics

Proceedings Volume 8825, 88250K (2013) https://doi.org/10.1117/12.2030377

KEYWORDS: Reliability, Photovoltaics, Solar cells, Phase modulation, Manufacturing, Physics, Humidity, Phase only filters, Accelerated life testing, Finite element methods

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Proceedings Article | 11 March 2013 Paper

Buckling conditions for a dual-coated optical fiber

Ephraim Suhir

Proceedings Volume 8621, 86210Z (2013) https://doi.org/10.1117/12.979767

KEYWORDS: Coating, Glasses, Optical fibers, Fiber coatings, Interfaces, Structured optical fibers, Composites, Temperature metrology, Thermography, Reliability

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Proceedings Article | 24 February 2010 Paper

Fiber optic interconnects: physical design for reliability

E. Suhir

Proceedings Volume 7607, 760717 (2010) https://doi.org/10.1117/12.846605

KEYWORDS: Optical fibers, Fiber optics, Optical coatings, Silica, Reliability, Cladding, Polymers, Mechanics, Fiber coatings, Glasses

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Proceedings Article | 28 February 2006 Paper

Fiber optics structural mechanics and nanotechnology-based new generation of fiber coatings

E. Suhir

Proceedings Volume 6126, 612606 (2006) https://doi.org/10.1117/12.661295

KEYWORDS: Optical fibers, Optical coatings, Fiber optics, Glasses, Polymers, Reliability, Mechanics, Fiber coatings, Structured optical fibers, Polymer optical fibers

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This paper consists of two parts - review and extension. The review part deals with typical fiber optics structures (bare, single- and dual-coated fibers; fibers experiencing low temperature micro-bending; fibers soldered into ferrules or adhesively bonded into capillaries; role of the non-linear stress-strain relationship, etc.) subjected to thermally induced and/or mechanical loading in bending, tension, compression, or to various combinations of such loadings. The emphasis is on the state-of-the-art in the area of optical fiber coatings and the functional (optical), mechanical and environmental problems that occur in polymer-coated or metallized fibers. The solutions to the examined problems are obtained using analytical methods (predictive models) of structural mechanics. The review is based primarily on the author's research conducted at Bell Laboratories, Murray Hill, NJ, during his eighteen years tenure with this company. The extension part addresses a new generation of optical fiber coatings and deals with the application of a newly developed (by the ERS/Siloptix Co.) nano-particle material (NPM) that is used as an attractive substitute for the existing optical fiber coatings. This NPM-based coating has all the merits of polymer and metal coatings, but is free of their shortcomings. The developed material is an unconventional inhomogeneous "smart" composite material, which is equivalent to a homogeneous material with the following major properties: low Young's modulus, immunity to corrosion, good-to-excellent adhesion to adjacent material(s), non-volatile, stable properties at temperature extremes (from -220°C to +350°C), very long (practically infinite) lifetime, "active" hydrophobicity - the material provides a moisture barrier (to both water and water vapor), and, if necessary, can even "wick" moisture away from the contact surface; ability for "self-healing" and "healing": the NPM is able to restore its own dimensions, when damaged, and is able to fill existing or developed defects (cracks and other "imperfections") in contacted surfaces; very low (near unity) effective refractive index (if needed). NPM can be designed, depending on the application, to enhance those properties most important. NPM properties have been confirmed through testing. The tests have demonstrated the outstanding mechanical reliability, extraordinary environmental durability and, in particular applications, improved optical performance of the light guide.

Proceedings Article | 11 March 2003 Paper

Accelerated life testing in photonics packaging: its objectives, role, attributes, challenges, pitfalls, predictive models, and interaction with other accelerated stress categories

Ephraim Suhir

Proceedings Volume 4947, (2003) https://doi.org/10.1117/12.476691

KEYWORDS: Reliability, Accelerated life testing, Manufacturing, Photonics, Humidity, Physics, Finite element methods, Data modeling, Laser welding, Semiconductor lasers

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Proceedings Article | 7 June 2002 Paper

Accelerated life testing (ALT) in microelectronics and photonics: its role, attributes, challenges, pitfalls, and interaction with qualification tests

Ephraim Suhir

Proceedings Volume 4703, (2002) https://doi.org/10.1117/12.469620

KEYWORDS: Reliability, Accelerated life testing, Manufacturing, Photonics, Microelectronics, Humidity, Nondestructive evaluation, Finite element methods, Data modeling, Physics

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