Current Search: Micro optics (x)
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(1 - 8 of 8)
- Title
- SELECTIVE MODE EXCITATION IN SPECIALTY WAVEGUIDES USING MICRO OPTICAL ELEMENTS.
- Creator
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Mohammed, Waleed, Johnosn, Eric, University of Central Florida
- Abstract / Description
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Although optical fibers and specialty waveguides are the base of majority of today's telecom and light delivery applications, fabrication deformation, nonlinearity and attenuation limit the bandwidth of the data being transmitted or the amount of power carried by these systems. One-way to overcome these limitations without changing the fibers design or fabrication is to engineer the input light in order to excite a certain mode or a group of modes with unique optical properties. Diffractive...
Show moreAlthough optical fibers and specialty waveguides are the base of majority of today's telecom and light delivery applications, fabrication deformation, nonlinearity and attenuation limit the bandwidth of the data being transmitted or the amount of power carried by these systems. One-way to overcome these limitations without changing the fibers design or fabrication is to engineer the input light in order to excite a certain mode or a group of modes with unique optical properties. Diffractive and micro optics are highly effective for selectively coupling light to specific modes. Using micro optics, mode selective coupling can be achieved through several matching schemes: phase only, phase and amplitude, or phase, amplitude and polarization. The main scope of this work is the design and fabrication of novel optical elements that overcome the limitations of these light delivery systems, as well as the characterization and analysis of their performance both experimentally and using numerical simulation
Show less - Date Issued
- 2004
- Identifier
- CFE0000171, ucf:46163
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0000171
- Title
- DESIGN AND OPTIMIZATION OF NANO-OPTICAL ELEMENTS BY COUPLING FABRICATION TO OPTICAL BEHAVIOR.
- Creator
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Rumpf, Raymond, Johnson, Eric, University of Central Florida
- Abstract / Description
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Photonic crystals and nanophotonics have received a great deal of attention over the last decade, largely due to improved numerical modeling and advances in fabrication technologies. To this day, fabrication and optical behavior remain decoupled during the design phase and numerous assumptions are made about "perfect" geometry. As research moves from theory to real devices, predicting device behavior based on realistic geometry becomes critical. In this dissertation, a set of numerical tools...
Show morePhotonic crystals and nanophotonics have received a great deal of attention over the last decade, largely due to improved numerical modeling and advances in fabrication technologies. To this day, fabrication and optical behavior remain decoupled during the design phase and numerous assumptions are made about "perfect" geometry. As research moves from theory to real devices, predicting device behavior based on realistic geometry becomes critical. In this dissertation, a set of numerical tools was developed to model micro and nano fabrication processes. They were combined with equally capable tools to model optical performance of the simulated structures. Using these tools, it was predicted and demonstrated that 3D nanostructures may be formed on a standard mask aligner. A space-variant photonic crystal filter was designed and optimized based on a simple fabrication method of etching holes through hetero-structured substrates. It was found that hole taper limited their optical performance and a method was developed to compensate. A method was developed to tune the spectral response of guided-mode resonance filters at the time of fabrication using models of etching and deposition. Autocloning was modeled and shown that it could be used to form extremely high aspect ratio structures to improve performance of form-birefringent devices. Finally, the numerical tools were applied to metallic photonic crystal devices.
Show less - Date Issued
- 2006
- Identifier
- CFE0001159, ucf:46849
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0001159
- Title
- ADDITIVE LITHOGRAPHY FABRICATION AND INTEGRATION OF MICRO OPTICS.
- Creator
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Pitchumani, Mahesh, Johnson, Eric, University of Central Florida
- Abstract / Description
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Optical elements are the fundamental components in photonic systems and are used to transform an input optical beam into a desired beam profile or to couple the input beam into waveguides, fibers, or other optical systems or devices. Macroscopic optical elements are easily fabricated using grinding and polishing techniques, but few methods exist for inexpensive fabrication of micro optical elements. In this work we present an innovative technique termed Additive Lithography that makes use of...
Show moreOptical elements are the fundamental components in photonic systems and are used to transform an input optical beam into a desired beam profile or to couple the input beam into waveguides, fibers, or other optical systems or devices. Macroscopic optical elements are easily fabricated using grinding and polishing techniques, but few methods exist for inexpensive fabrication of micro optical elements. In this work we present an innovative technique termed Additive Lithography that makes use of binary masks and controlled partial exposures to sculpt photoresist into the desired optical surface relief profile. We explore various masking schemes for fabricating a variety of optical elements with unprecedented flexibility and precision. These masking schemes used in conjunction with the additive lithographic method allows us to carefully control the photoresist exposure and reflow processes for fabricating complex aspheric lens elements, including aspheric elements whose fabrication often proves highly problematic. It will be demonstrated that employing additive lithography for volume sculpting followed by controlled reflow can also allow us to fabricate refractive beam shaping elements. Finally we will discuss the dry etching techniques used to transfer these optical elements into the glass substrate. Thus the additive lithography technique will be demonstrated as an inexpensive, high throughput and efficient process in the fabrication of micro optical elements.
Show less - Date Issued
- 2006
- Identifier
- CFE0000914, ucf:46761
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0000914
- Title
- A NEW HYBRID DIFFRACTIVE PHOTO-MASK TECHNOLOGY.
- Creator
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Sung, Jin Won, Johnson, Eric, University of Central Florida
- Abstract / Description
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In the field of photolithography for micro-chip manufacturing, the photo-mask is used to print desired patterns on a proper photo-resist on wafer. The most common type of photo-mask is binary amplitude mask made an opaque layer of chrome. The principle and potential application of hybrid photo-mask with diffractive phase element and binary amplitude is presented in this dissertation paper from both numerical modeling and experimental research. The first important application is the...
Show moreIn the field of photolithography for micro-chip manufacturing, the photo-mask is used to print desired patterns on a proper photo-resist on wafer. The most common type of photo-mask is binary amplitude mask made an opaque layer of chrome. The principle and potential application of hybrid photo-mask with diffractive phase element and binary amplitude is presented in this dissertation paper from both numerical modeling and experimental research. The first important application is the characterization of aberration in the stepper system using hybrid diffractive photo-mask. By utilizing multiple diffractive illumination conditions, it is possible to characterize Zernike wave front aberration coefficients up to any desired order. And, the second application is the use of binary phase grating mask for analog micro-optics fabrication. This approach of using binary phase grating mask for fabricating analog micro-optics turned out to be a very effective alternative for gray-scale mask technology. Since this is a pure phase only mask, it doesn't cause any scattered noise light like half-tone mask and it results in smooth desired resist profile. The benefits and limitations of hybrid diffractive photo-mask approach for both applications are discussed.
Show less - Date Issued
- 2005
- Identifier
- CFE0000350, ucf:46296
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0000350
- Title
- DESIGN AND ASSESSMENT OF COMPACT OPTICAL SYSTEMS TOWARDS SPECIAL EFFECTS IMAGING.
- Creator
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Chaoulov, Vesselin, Rolland, Jannick, University of Central Florida
- Abstract / Description
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A main challenge in the field of special effects is to create special effects in real time in a way that the user can preview the effect before taking the actual picture or movie sequence. There are many techniques currently used to create computer-simulated special effects, however current techniques in computer graphics do not provide the option for the creation of real-time texture synthesis. Thus, while computer graphics is a powerful tool in the field of special effects, it is neither...
Show moreA main challenge in the field of special effects is to create special effects in real time in a way that the user can preview the effect before taking the actual picture or movie sequence. There are many techniques currently used to create computer-simulated special effects, however current techniques in computer graphics do not provide the option for the creation of real-time texture synthesis. Thus, while computer graphics is a powerful tool in the field of special effects, it is neither portable nor does it provide work in real-time capabilities. Real-time special effects may, however, be created optically. Such approach will provide not only real-time image processing at the speed of light but also a preview option allowing the user or the artist to preview the effect on various parts of the object in order to optimize the outcome. The work presented in this dissertation was inspired by the idea of optically created special effects, such as painterly effects, encoded in images captured by photographic or motion picture cameras. As part of the presented work, compact relay optics was assessed, developed, and a working prototype was built. It was concluded that even though compact relay optics can be achieved, further push for compactness and cost-effectiveness was impossible in the paradigm of bulk macro-optics systems. Thus, a paradigm for imaging with multi-aperture micro-optics was proposed and demonstrated for the first time, which constitutes one of the key contributions of this work. This new paradigm was further extended to the most general case of magnifying multi-aperture micro-optical systems. Such paradigm allows an extreme reduction in size of the imaging optics by a factor of about 10 and a reduction in weight by a factor of about 500. Furthermore, an experimental quantification of the feasibility of optically created special effects was completed, and consequently raytracing software was developed, which was later commercialized by SmARTLens(TM). While the art forms created via raytracing were powerful, they did not predict all effects acquired experimentally. Thus, finally, as key contribution of this work, the principles of scalar diffraction theory were applied to optical imaging of extended objects under quasi-monochromatic incoherent illumination in order to provide a path to more accurately model the proposed optical imaging process for special effects obtained in the hardware. The existing theoretical framework was generalized to non-paraxial in- and out-of-focus imaging and results were obtained to verify the generalized framework. In the generalized non-paraxial framework, even the most complex linear systems, without any assumptions for shift invariance, can be modeled and analyzed.
Show less - Date Issued
- 2005
- Identifier
- CFE0000513, ucf:46447
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0000513
- Title
- DESIGN AND FABRICATION OF SPACE VARIANT MICRO OPTICAL ELEMENTS.
- Creator
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Srinivasan, Pradeep, LiKamWa, Patrick, University of Central Florida
- Abstract / Description
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A wide range of applications currently utilize conventional optical elements to individually transform the phase, polarization, and spectral transmission/reflection of the incident radiation to realize the desired system level function. The material properties and the feasibility of fabrication primarily impact the device and system functionality that can be realized. With the advancement in micro/nano patterning, growth, deposition and etching technology, devices with novel and multiplexed...
Show moreA wide range of applications currently utilize conventional optical elements to individually transform the phase, polarization, and spectral transmission/reflection of the incident radiation to realize the desired system level function. The material properties and the feasibility of fabrication primarily impact the device and system functionality that can be realized. With the advancement in micro/nano patterning, growth, deposition and etching technology, devices with novel and multiplexed optical functionalities have become feasible. As a result, it has become possible to engineer the device response in the near and far field by controlling the phase, polarization or spectral response at the micro scale. One of the methods that have been explored to realize unique optical functionalities is by varying the structural properties of the device as a function of spatial location at the sub-micron scale across the device aperture. Spatially varying the structural parameters of these devices is analogous to local modifications of the material properties. In this dissertation, the optical response of interference transmission filters, guided mode resonance reflection filters, and diffraction gratings operated in Littrow condition with strategically introduced spatial variation have been investigated. Spatial variations in optical interference filters were used to demonstrate wavelength tunable spatial filters. The effect was realized by integrating diffractive and continuous phase functions on the defect layer of a one-dimensional photonic crystal structure. Guided mode resonance filters are free space optical filters that provide narrow spectral reflection by combining grating and waveguide dispersion effects. Frequency dependent spatial reflection profiles were achieved by spatially varying the grating fill fraction in designed contours. Diffraction gratings with space variant fill fractions operating in Littrow condition were used to provide graded feedback profiles to improve the beam quality and spatial brightness of broad area diode lasers. The fabrication of space variant structures is challenging and has been accomplished primarily by techniques such as ruling, electron beam writing or complex deposition methods. In order to vary the desired structural parameter in a designed manner, a novel technique for the fabrication of space variant structures using projection lithography with a fidelity that rivals any of the current technologies was also developed as a part of this work. The devices exhibit wavelength dependent beam shaping properties in addition to spatial and spectral filtering and have potential applications in advanced imaging systems, graded reflectivity laser mirrors, and engineered illumination. The design, modeling, microfabrication and experimental characterization of space variant micro optical elements with novel optical functionalities are presented.
Show less - Date Issued
- 2009
- Identifier
- CFE0002843, ucf:48066
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0002843
- Title
- Novel Photonic Resonance Arrangements Using Non-Hermitian Exceptional Points.
- Creator
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Hodaeiesfahani, Seyedhossein, Khajavikhan, Mercedeh, Christodoulides, Demetrios, Likamwa, Patrick, Abdolvand, Reza, University of Central Florida
- Abstract / Description
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In recent years, non-Hermitian degeneracies also known as exceptional points (EPs) have emerged as a new paradigm for engineering the response of optical systems. EPs can appear in a wide class of open non-Hermitian configurations. Among different types of non-conservative photonic systems, parity-time (PT) symmetric arrangements are of particular interest since they provide an excellent platform to explore the physics of exceptional points. In this work, the intriguing properties of...
Show moreIn recent years, non-Hermitian degeneracies also known as exceptional points (EPs) have emerged as a new paradigm for engineering the response of optical systems. EPs can appear in a wide class of open non-Hermitian configurations. Among different types of non-conservative photonic systems, parity-time (PT) symmetric arrangements are of particular interest since they provide an excellent platform to explore the physics of exceptional points. In this work, the intriguing properties of exceptional points are utilized to address two of the long standing challenges in the field of integrated photonics- enforcing single mode lasing in intrinsically multimode cavities and enhancing the sensitivity of micro-resonators.In the first part of this work, I will describe how stable single mode lasing can be readily achieved in longitudinally and transversely multi-moded microring cavities through the systematic utilization of abrupt phase transitions at exceptional points. This technique will be first demonstrated in a parity-time laser that is comprised of a gain cavity coupled to an identical but lossy counterpart. A detailed study of the behavior of this system around the exceptional point will be presented. Furthermore, we report the first experimental realization of a dark state laser in which by strategically designing the spectral locations of exceptional points, widely tunable single-mode lasing can be attained even at high pump levels. Despite the presence of loss in such open laser systems, the slope efficiency remains virtually intact. Our results demonstrate the potential of exceptional points as a versatile design tool for mode management in on-chip laser configurations.In the second part of my dissertation, I will show how the exceptional points and their underlying degeneracies can be used to significantly boost the intrinsic sensitivity of microcavities. I will demonstrate the enhanced sensitivity in a binary PT-symmetric coupled cavity arrangement that is biased at an exceptional point. Then I will report the first observation of higher-order exceptional points in a ternary parity-time symmetric microring laser system with a judiciously tailored gain-loss distribution. The enhanced response associated with this ternary system follows a cubic root dependence on externally introduced perturbation, which can in turn be detected in the spectral domain. Using such arrangements, more than one order of magnitude enhancement in the sensitivity is observed experimentally. These results can pave the way towards improving the performance of current on-chip micro-cavity sensors.
Show less - Date Issued
- 2017
- Identifier
- CFE0006947, ucf:51627
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0006947
- Title
- Design, Development, and Testing of a Miniature Fixture for Uniaxial Compression of Ceramics Coupled with In-Situ Raman Spectrometer.
- Creator
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Jordan, Ryan, Orlovskaya, Nina, Kwok, Kawai, Ghosh, Ranajay, University of Central Florida
- Abstract / Description
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This thesis is about the design, development and integration of an in-situ compression stage which interfaces through the Leica optical microscope coupled with a Renishaw InVia micro-Raman spectrometer. This combined compression stage and Raman system will enable structural characterization of ceramics and ceramic composites. The in-situ compression stage incorporates a 440C stainless steel structural components, 6061 aluminum frame, a NEMA 23 stepper motor. Two load screws that allow to...
Show moreThis thesis is about the design, development and integration of an in-situ compression stage which interfaces through the Leica optical microscope coupled with a Renishaw InVia micro-Raman spectrometer. This combined compression stage and Raman system will enable structural characterization of ceramics and ceramic composites. The in-situ compression stage incorporates a 440C stainless steel structural components, 6061 aluminum frame, a NEMA 23 stepper motor. Two load screws that allow to apply compressive loads up to 14,137 N, with negligible off axis loading, achieving target stresses of 500 MPa for samples of up to 6.00 mm in diameter. The system will be used in the future to study the structural changes in ceramics and ceramic composites, as well as to study thermal residual stress redistribution under applied compressive loads. A broad variety of Raman active ceramics, including the traditional structural ceramics 3mol%Y2O3-ZrO2, B4C, SiC, Si3N4, as well as exotic materials such as LaCoO3 and other perovskites will be studied using this system. Calibration of the systems load cell was performed in the configured state using MTS universal testing machines. To ensure residual stresses from mounting the load cell did not invalidate the original calibration, the in-situ compression stage was tested once attached to the Renishaw Raman spectrometer using LaCoO3 ceramic samples. The Raman shift of certain peaks in LaCoO3 was detected indicative of the effect of the applied compressive stress on the ceramics understudy.
Show less - Date Issued
- 2019
- Identifier
- CFE0007824, ucf:52809
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0007824
