bluuebunny/crossref_metadata_2025 huggingface dataset:
Enhancement of conversion efficiency in second-harmonic generation by a partially coherent source
Authors: Ansari Nadeem A. , McIver J. K. , Zubairy M. S.
Published: February 2023

When a coherent beam is incident on a random phase screen, such as a rotating ground glass plate, the phase fluctuations in the emerging beam tend to decrease the coherence. The coherence properties of the beams generated by such partially coherent sources have been studied extensively in recent years. In this paper, we discuss the effect of degrading the spatial coherence of the pump beam on the conversion efficiency in the second-harmonic process. We consider the situation in which a laser beam whose coherence has been degraded by a random phase screen propagates in a nonlinear medium. We restrict ourselves to the situation where the conversion efficiency is not very large so that the parametric approximation is valid. For the description of the random phase screen we consider two models: (1) a Gaussian Schell-model source1 and (2) a model due to Berry.2 Our results indicate that by an appropriate choice of parameters it should be possible to enhance the conversion efficiency of the second-harmonic beam by a factor of 2, compared to a coherent laser. We also present reciprocity relations between the coherence and intensity distributions of the pump beam in the entrance plane and the second-harmonic beam in the exit plane.
Experimental observation of laser trapping of atoms
Authors: Bjorkholm J. E. , Chu Steven , Ashkin A. , Cable A.
Published: February 2023

We recently made the first observation of the optical trapping of neutral atoms by the forces of resonance-radiation pressure. We present an updated view of our experimental efforts on optical trapping.
Light traps using spontaneous forces
Authors: Pritchard D. E. , Wieman C. E. , Raab E. L. , Watts R. N. , Bagnato V. , Stoner R.
Published: February 2023

We propose several ideas for neutral atom traps which utilize spontaneous light forces produced by static laser beams. Although the “optical Earnshaw theorem”1 would seem to prohibit such traps, the theorem does not apply if the proportionality constant between force and light intensity is made to vary with position. We suggest possible ways to accomplish this: Zeeman tuning the atom’s resonant frequency by applying a changing magnetic field; varying the quantization axis of the system via a magnetic field cork-screw; utilizing optical pumping effects which arise from matrix element imbalances between hyperfine sublevels in certain atoms. These traps are true in the sense that they provide a potential energy minimum in three dimensions, as well as dissipative cooling. Compared with gradient force light traps, these traps are many times deeper, a million times larger, and can be operated cw.
Improved collection powers of an optical Maxwell demon
Authors: Migdall A. L. , Metcalf H. J. , Phillips W. D. , Gould P. L.
Published: February 2023

We present an improvement of our previously proposed optical Maxwell demon1 that captures and cools Na atoms in a gas cell. The intersection of three pairs of orthogonal counterpropagating light beams tuned below resonance provides strong viscous forces on atoms.2 In a vapor cell, it is the ability of atoms to enter this intersection from the outside that allows our demon to collect a high density of cold atoms. The original scheme suffers a reduced collection rate because the 3-D damping region is largely surrounded by a region of 1-D damping produced by only a single pair of beams. This deficiency can be removed by several methods, one of which involves optical pumping. Sodium requires two frequencies to prevent optical pumping and maintain the damping force. If two pairs of beams contain one frequency and the third pair contains the other frequency, the effect of the 1-D damping is reduced while the region of 3-D damping is largely unaffected. Thus, an atom can enter the intersection undeflected by a region containing only a single pair of beams. We present computer analysis and experimental progress.
Short-wavelength limitations of four-wave mixing in gases
Authors: Scheingraber H. , Vidal C. R.
Published: February 2023

In describing four-wave mixing in gases1 it is useful to distinguish three different intensity regimes: small signal limit; onset of saturation; and high intensity saturation. For optimum conditions one should stay in the regime of the onset of saturation where field-dependent changes of the refractive index start to destroy the phase matching condition. In going to shorter wavelengths a number of competing processes have to be considered: sum frequency mixing, such as difference frequency mixing; two-photon absorption; stimulated emission and parametric processes; redistribution of population densities; and field-dependent changes of the refractive index.
Three-Mirror Off-Axis Systems for Laser Applications
Authors: Beckmann Leo H. J. F. , Ehrlichmann Dietmar
Published: February 2023

For the focussing of high power (>5kW) carbon dioxide laser radiation, mirror systems are preferable to lenses. While off-axis paraboloidal mirrors are often suggested for this application, their very small field causes severe alignment problems in practice. A series of all-spherical, off-axis 3-mirror systems has been designed as an alternative, which offers attractive features. The sequence of powers is + - +, and a fourth, flat, mirror can be placed conveniently behind the first, concave, mirror to set the exiting axis parallel or perpendicular to the incoming beam. This leads to four angular configurations (pnpn, nnpn, pppn and nppn) all of which have merits. At speeds of up to f/4, and with a back focus larger than the focal length, these systems are particularly attractive for applications in laser welding, but the excellent performance of the systems pnpn and pppn over field angles of more than 1 degree makes them suitable for other applications as well. Aberration characteristics and their dependence on configuration are discussed. A sample system has been built and tested. It verifies the expected performance and shows practical advantages over a comparable off-axis paraboloid.
General Differential Ray Trace
Authors: Harrigan Michael
Published: February 2023

This talk will describe how to trace exact differential skew rays. They are fundamental to the complete first-order characterization of general optical systems and the propagation of non-Gaussian beams through such systems.
Comprehensive Theory of Primary and Secondary Color Correction of Arbitrary Optical Systems
Authors: Herloski Robert
Published: February 2023

A method of calculating and correcting primary and higher order chromatic aberrations of arbitrary optical systems is discussed. This method uses Buchdahl’s chromatic aberration theory [1] to calculate the exact chromatic aberration coefficients (axial and lateral color of any order) of a given optical system, with no restriction on element thickness or spacing. This theory is rewritten so that the color correction problem is approximated by a series of homogeneous linear equations, which can be solved by graphical or linear algebraic techniques. This formulation gives a lens designer the ability to easily and systematically choose glasses that can potentially correct the chromatic aberrations of a complex lens system. Several design examples are given that illustrate the application of this method to lens systems with finite element thicknesses and separations. It is shown that this method can directly accommodate diffractive optical elements (DOE’s) and that DOE’s can be used to correct higher order chromatic aberrations of lens systems that could not otherwise be corrected.
Correction of Fifth-Order Aberrations with an Enhanced Version of the Adaptive Method
Authors: Hull C. C.
Published: February 2023

A modified version of the Adaptive Method has been used to reduce the fifth order aberrations of two designs; one a high aperture IR triplet and the other a Retrofocus photographic lens. It was found that the designs with reduced fifth order aberrations had strong curvatures to affect this correction which were not present to such a great extent in the final balanced designs. Damped least squares optimization lead to a better solution, and with a faster rate of convergence, for the IR triplet but did not show the same advantage for the Retrofocus lens which had a starting design which more closely approximated the final lens form.
Practical Lens Design Using a Global Method
Authors: Kuper Thomas G. , Harris Thomas I. , Hilbert Robert S.
Published: February 2023

We apply the Global Synthesis® (GS) optimization algorithm to a locally optimized, wide angle mapping lens patent (59 variables), and achieve twice the patent's as-built performance. Results are also given for the application of GS to the 1994 IODC lens design problem.
SVD, Transformations, and the Search for a Better Minimum
Authors: Loomis John S.
Published: February 2023

Singular Value Decomposition (SVD) is the method of choice for solving ill-conditioned systems of linear This paper will give geometrical interpretations of SVD as applied to the problem of optical design. Although these interpretations suggest an orthogonalization of variables and defects, we will show that such orthogonalization is not appropriate for most optical design problems. A simplified set of transformations, however, does provide insight on some of the classic problems of lens design. Finally, we will present some current work on curvilinear “valley” following methods and show their application to optical design.
Design of Depolarizers for Space-Borne Instruments by Birefringent Polarization Ray Tracing
Authors: McClain Stephen C. , Chipman Russell A.
Published: February 2023

Depolarizers have been designed using birefringent ray tracing. Their purpose is to increase the radiometric accuracy of space-borne instruments, such as radiometers and spectroradiometers, by reducing the linear polarization sensitivity induced by the optical system.
Use of Expendable Aspherics to Improve the Convergence of Iterative Lens Design
Authors: Rosete-Aguilar M. , Maxwell J.
Published: February 2023

The principal problem in iterative lens design methods is the requirement to find paths in multidimensional parameter space between where you are and where you would like to be. There are no restrictions on the tricks that may be employed to seek out useful paths and one method that may be used to improve the navigational process is to employ aspheric surfaces as a temporal expedient and to treat the aspheric coefficients as aberrations. The application of this method to a specific case is given and the value of the method for more general use is discussed.
Modelling of Diffractive Optics
Authors: Farn Michael W.
Published: February 2023

Methods used in analyzing surface-relief diffractive optics (a.k.a., binary optics) are described, both theoretically and by design example. Special emphasis is given to the issue of diffraction efficiency.
Iterative Methods for the Kinoforms Synthesis
Authors: Khonina S. N. , Kotlyar V. V. , Nikolsky I. V. , Philippov S. V. , Soifer V. A.
Published: February 2023

Three iterative algorithms for calculating kinoforms are discussed: 1) an algorithm for calculating kinoforms with quantized phase forming radially symmetric images, 2) an algorithm for calculating formers of Gauss-Hermite's and Gauss-Leguerre’s modes in required diffraction orders, 3) an algorithm for calculating formers of reference wavefronts. The results of computer-aided simulation are given.
Verification of a MTF Linear Model and Application for Error Budget Allocation
Authors: Kuo Chai-Pei , Figoski John W.
Published: February 2023

A linear relationship between the MTF degradation and the wavefront variance has been developed for small wavefront error perturbation. A sensitivity coefficient can then be defined to aid both the design and error budgeting process. For error budgeting, this coefficient is applied to predict change in performance of a nearly diffraction-limited optical imaging system due to manufacture and assembly errors. This leads to a fast and accurate way to create an error budget and explore ideal distribution of individual terms. A CODE V verification model will be presented to show the range of wavefront error that this MTF linear degradation model applied. Further, an example of an error budget spread sheet will illustrate how this model is used to determine the best distribution of error allocations.
Calculation of 3-Bar Resolution from OTF Data: Possible Problems
Authors: Rogers John R.
Published: February 2023

The resolution of 3-bar targets is an established criterion for the quality of optical systems; however, most optical design programs calculate the OTF function rather than the 3-bar resolution. In order to be able to predict the resolution of a system before it is built and experimentally tested, a conversion of the OTF data to resolution data would be useful. This paper deals with the problems associated with this conversion. A calculation method is given which correctly accounts for the following properties of 3-bar imaging: square-wave vs. sine-wave object; finite vs. infinite number of cycles in the pattern; linear systems theory vs. non-linear film behavior.

It is shown that the use of a threshold function for the MTF can lead to incorrect results, since the threshold function method does not take the shape of the MTF curve into account. Furthermore, it is shown that when 3-bar resolution is measured using the ANSI standard resolution chart, the resolution of a particular pattern may be significantly affected by the presence of neighboring patterns. It is seen that the use of highly non-linear film for resolution testing can lead to inaccurate measurements.
Tolerant Design of Planar Optical Interconnections
Authors: Jahns Jürgen
Published: February 2023

For interconnection and sensor applications the use of conventional optomechanical packaging results in problems because of its bulkiness, the difficulty to achieve tight and stable alignment, and cost. Planar optics is an approach to solve the packaging problem by integrating free-space optical systems on single substrates. By using lithographic fabrication techniques for the microoptics, high alignment precision, mechanical and thermal stability are achieved. For practical applications, it is necessary to consider the influence of substrate variations like thickness tolerances and wedges between the substrate surfaces or the influence of wavelength variations on the performance of a system. In particular, it is of interest to design the optical system in such a way that it becomes insensitive to tolerances of the substrate parameters or the wavelength of the light.
2D Fiber Connector Based on Refractive and Diffractive Optics for Intracomputer Communication
Authors: Lalanne Philippe , Kufner Maria , Kufner Stephan , Chavel Pierre
Published: February 2023

A 2D monomode fiber connector based on monolithic integration of micromachined holes and microlenses is proposed. Combined with diffractive optics, this device shows fanout flexibility.
Low-Cost Integrating Sphere for Uniform Illumination
Authors: Ducharme Alfred D. , Boreman Glenn D. , Daniels Arnold , Grann Eric B.
Published: February 2023

A design for an inexpensive integrating sphere for use as a uniform source of illumination in the visible spectrum is presented. The design was realized and the fabrication process is outlined, detailing important considerations for assuring uniformity. The performance of the completed sphere is given as a measure of the uniformity of the radiance at the exit port.
Design of Optoelectronic Devices for Hidden and Internal Observation
Authors: Anitropova Irina L. , Bronstein Igor G. , Krilov Victor M.
Published: February 2023

A brief description of the design method for miniature lenses for optoelectronic devices is presented. The main principle, which was used for optical design here is the combining of optical elements for achieving different technical characteristics using one basic objective only. For example, when combining eight different optical elements, having as basic three-lens objective with removed forward entrance pupil, one can get a lenses family with angular fields 40, 50, 60, 70, 90 и 114 angular degrees, which correspond to the size of receiver’s diagonal for modem CCD receivers, such as 1/3”, 1/2” и 2/3". Aperture number is not less than F2 for all lenses. Examples are given.
Design of a Re-Imaging Cassegrain Bifocal Lens with Hybrid Elements for High Resolution Night Surveillance Applications
Authors: Kaneko Keiichiro , Dereniak Eustace L.
Published: February 2023

A design of a narrow field of view (FOV) lens for night viewing has been considered. The lens is a re-imaging Cassegrain bifocal system with hybrid elements and has a resolution of 0.0875 (mrad). The advantages of this design include the following: no large refractive element, fewer refractive elements (three germanium lenses), no stow space for removed lenses or mirrors, only one moving group to change the field of view. The narrow FOV is 0.95 (deg) and the spectral region used for the system is 8.5 pm to 12.5 µm. Noise Equivalent Temperature Difference (NETD) is calculated based on the assumption that the imaging system has an uncooled staring array detector.
Near-Field Stray Light Rejection Techniques for the Moderate Resolution Spectroradiometer (MODIS)
Authors: Kampe Thomas U. , Waluschka Eugene
Published: February 2023

Near-field scattered light, due to ghost images produced from multiple reflections or due to scatter off optical surfaces, will contribute to background noise. This background noise can reduce contrast and blur edge transitions. These sources of background noise cannot be compensated for since they are scene-dependent. High-performance remote sensing instruments, such as the Moderate Resolution Imaging Spectrometer (MODIS), have strict systems-level radiometric performance criteria, such as transient response and stray light, which demand that background noise sources be well controlled. This paper discusses design challenges brought on by these requirements and subsequent modifications and analysis techniques used to minimize ghosting for the MODIS instrument.
A method of evaluating and tolerancing interferometer designs
Authors: Michaloski Paul , Kulawiec Andrew , Fleig Jon
Published: February 2023

The design of the optics for interferometers can often be performed on standard design software with simple assumptions about the laser feed, viewing systems and the surface under test. The problem is that these assumptions quickly become inadequate when modeling perturbations to the system. Yet one of the advantages of using the standard design software is the ease that these perturbations can easily be introduced to the model. The need to examine such perturbations as alignment errors, optical fabrication errors, thermal effects and propagation errors due to non­null test surfaces led to the development of a simple method for evaluating and tolerancing interferometers. The following covers the method of the analysis, along with its advantages and disadvantages. The method is applied to the analysis of a form measuring phase interferometer designed to test the cylindricity of mechanical parts and the predicted performance is compared to experimental results.
Current Developments in GRADIUM® Glass Technology
Authors: Hunter Boyd V. , Tyagi Vineet , Tinch David A. , Fournier Paul
Published: February 2023

Many improvements have been made in LightPath’s products since the public offering. The manufacturability of the initial GSF glasses has been improved, thus improving repeatability and mechanical properties. We have demonstrated the ability to make a profile to match the prescription rather than adapt an existing profile to a design (although making a custom profile must be justified by volume). We continue to improve our modeling of the profiles to make theory and reality coincide. For example, in early 1997, profile release 97-2 provided statistically based profile definitions of standard profiles.
Aberration balance in error functions calculated analytically
Authors: Bociort Florian
Published: February 2023

Progress in global optimization methods and the availability of fast computers have lead in the past few years to increasingly powerful lens design software that is capable to detect multiple local minima corresponding to given system specifications. However, there is still no known technique to determine whether the local minimum having the lowest value of the error function among those already detected is indeed the global minimum, especially if the number of optimization variables is large. While this continues to be a very difficult problem, in this paper we present a new technique of optical system analysis which may shed some new light on this issue.
Global optimization with escape function
Authors: Isshiki Masaki
Published: February 2023

In the optimization of lens design, the damped least squares method (DLS) allows us to find a solution easily, but it corresponds to a local minimum of the merit function which happens to lie near the starting design. There must be many other solutions in the wider area, some of which can be much better than the first solution. When the design falls into a local minimum, it is almost impossible with DLS to get out of that trap to find other solutions, because the control of damping factor forces the design to remain within that trap.
Global and Multi-objective Optimization for Lens Design by Real-coded Genetic Algorithms
Authors: Ono Isao , Kobayashi Shigenobu , Yoshida Koji
Published: February 2023

Local search methods have been traditionally used in lens design. They have a serious problem that the quality of lenses found by them heavily depends on starting points. Recently, several global optimization methods for lens design have been proposed(1-5),(8). Of these studies, Betensky(1) and Chen, et al.(2) have proposed methods based on bit-string genetic algorithms and the DLS method. However, all conventional local and global methods for lens design do not explicitly handle plural criteria. Therefore, a lens designer must usually find an appropriate starting point and a proper tradeoff-ratio among plural criteria by trail and error.
Global optimization of zoom lenses
Authors: Yabe Akira
Published: February 2023

Escape function is defined as where x: Variable vector on parameter space u: Position vector of a local minimum H and W: Escape parameters.
Aberration polynomial fitting and MTF based optimization for general optical systems
Authors: Wang Yongtian , Tang Xingui , Li Lin
Published: February 2023

Although there are different ways to implement MTF optimization1,2 in an optical design program, a common requirement of them is to express the wave-aberration as a polynomial in the exit pupil coordinates. While in-depth studies have been carried out for polynomial fitting for rotationally symmetric optical systems3,4, few publications can be found on the subject for general systems without symmetry. A simple scheme is developed for the efficient and accurate determination of the coefficients of a Zernike wave-aberration polynomial for a given object point and a general optical system. It enables rapid evaluations of MTF related image criteria such as the variance of the wave-aberration difference function, which is used as the merit function in damped-least-squares MTF optimization for nonsymmetric systems.
TIMMI 2 a combined astronomical MIR Camera, Spectrometer, and Polarimeter for ESO
Authors: Dietzsch Eberhard
Published: February 2023

In the mid-IR (MIR) region there is often an excess radiation due to circumstellar or diffusely distributed interstellar matter and there are distinguished diagnostic spectral features. These bear information on the chemical and physical nature of the intervening solid particles (refractory materials and ices) and are indicative of the presence of shock fronts, e.g. In case of comets, information on the dust production rate and physical properties of cometary nuclei can be derived. From all these fields there is a strong need for mid-infrared imaging, as well as spectroscopic and polarimetric observations with high spatial and spectral resolution of objects such diverse as from solar system bodies, as e.g. comets, to active galactic nuclei. All this refers to the spectral regions at the 10 and 20-µm band, the astronomical N- and Q-bands corresponding to the atmospheric windows ranging from 7.5 to 13.3µm and 16 to 24µm respectively.
Refractive elements in spectrographs
Authors: Hopkins George W.
Published: February 2023

A spectrograph design was needed for an application in medical optics. Requirements for resolution were modest, cost was to be minimized, and every photon was precious. The initial design used a concave, aberration-corrected, holographically recorded, diffraction grating. This design cost too much and collected too few of the precious photons. Several design forms, which use refractive optics with a planar diffraction grating, were investigated. The design that was chosen and built uses two aspheric glass lenses, one for collimating and one for focusing, together with a planar diffraction grating.
A Hyperspectral Imaging Sensor for the Coastal Environment
Authors: Fisher John , Antoniades John , Rollins Chris , Xiang Lian
Published: February 2023

Space-borne remote sensing of the coastal environment has driven the development of hyperspectral imaging sensors with both high SNR and demanding image quality over a broad spectral range. Coastal scenes are characterized by the low albedo water adjacent to high albedo white sandy beaches, which drives optical specifications (fig.1) such as throughput, scattered light, and spectral channel cross-talk due to keystone distortion. Polarization insensitivity is also important for accurately fitting the measured radiance with algorithms for atmospheric correction. The design pursued by Navy EarthMap Observer (NEMO) Satellite Program is that of a three-mirror anastigmat (TMA) telescope followed by a common entrance slit to separate visible-near infrared (VNIR) and shortwave infrared (SWIR) imaging spectrographs. The telescope and VNIR spectrometer are shown in figure 2, with SWIR spectrograph and fold mirrors omitted for clarity.
Wide-Angular Zoom Lens with Removed Forward Entrance Pupil
Authors: Livshits-Anitropova Irina L. , Russinov Michael M. , Bronchtein Igor G.
Published: February 2023

In Russia television systems for security, hidden and internal (connected with fiber cables) observation, based on using CCD-cameras are especially booming.
Catadioptric Relay for Dual DMD Projectors
Authors: Caldwell J. Brian
Published: February 2023

A nearly diffraction limited catadioptric relay system is described which enables the use of very compact projection lenses with dual DMD projectors.
Optical material model statistical quality-of-fit evaluation method
Authors: Komiski Ronald J.
Published: February 2023

In order to design a refractive optical system, the lens designer needs to know at the wavelengths the system will operate the index of refraction of the materials that are going to be used for the elements. If the specifications of the design require high performance (e.g., diffraction-limited performance over an extended spectral band) then the optical dispersion of the material must be known to a high degree of accuracy. Visible wavelength band lens designs that use optical glasses can satisfy this need because the characteristics of optical glasses are established and well documented over the usable spectral band by the glass manufacturer (typically 0.40 to 2.3 microns). High-accuracy requirements for dispersion characteristics can present challenges to lens designers that have to develop high-performance designs when the design specifications rule out the use of optical glasses.
An Interferometer System Scheme for the Fast Measurement of Small Displacement
Authors: Li Ruiming , Aruga Tadashi
Published: February 2023

Various methods of absolute displacement measurement by means of optical interferometers have been presented in recent years[1] [2] [3]. The existing methods are generally feasible in low speed measurement cases. However, in some high speed measurement cases, one can find hardly a suitable technique if the measurement accuracy requirement is high. The speed limitation in the absolute displacement measurement interferometers is mainly due to the usage of slow modulation(or scanning) technique. It is difficult to improve the present modulation techniques for the fast measurement. Here we propose an interferometer system scheme and explore a new absolute displacement measurement principle by doing the numerical study. According to the numerical study, the scheme proposed provides the possibility to acquire quickly the absolute displacement measurement data within a small displacement range.
Optical Design Software for the Analysis of Thermal Effects
Authors: Li Lin , Wang Xuan , Wang Yongtian
Published: February 2023

Most optical systems are generally used in normal conditions, that means, in normal temperature and pressure. But some optical systems, for example, those specially used in remote satellite or in aerospace, may be affected by the thermal effects caused by the environmental temperature variation. Some deviations will take place in the refractive indices, curvatures, element thicknesses and airspaces of these systems due to the great variation and difference in temperature, pressure and radiation, and certainly the image quality of the systems will be also not as good as that before. Therefore, when we design these systems, the most important thing is to eliminate the thermal effects caused by the environmental temperature.
Use of SRS polarization spectral time gate for creation of lidar receiving systems
Authors: Bespalov Victor G. , Krylov Vitaly N. , Staselko Dmitry I.
Published: February 2023

We suggest using the SRS amplifier in the lidar receiving system, which will provide amplifying of weak coherent signal, its spectral discrimination and time gating, as well as polarization study at the same time.
Monolithic GaAs Circuit Elements for Integrated Optics*
Authors: Blum F. A. , Campbell J. C.
Published: February 2023

Realizing the ultimate potential of fiber optical communications technology for the rapid processing and transmission of information requires development of integrated optical circuits (IOC's). Reliable cost-effective techniques for the fabrication of transmitters and receivers containing lasers, waveguides, modulators, switches, couplers, and photo-detectors must be developed. The most promising emerging technology for IOC's is the formation of optical microcircuitry in the III-V semiconductor materials system (GaAs and its ternary alloys with Aℓ, In, etc.). A program for the development of a GaAs IOC transmitter such as shown in Figure 1 is being carried out. This IOC transmitter is to consist of a monolithic surface laser whose output is coupled into patterned channel waveguides. Modulation and switching of the radiation occur in the waveguide circuit and are controlled separately. These structures are to be fabricated monolithically on a single semiconductor chip with each device amenable to integrated, low-cost manufacture. The waveguide outputs of the IOC transmitter will be coupled to single mode optical fibers which form a transmission cable.
Investigation of GaAs/GaAlAs Waveguide Lasers with Second Order Distributed Feedback
Authors: Alferov Zh. I. , Gurevich S.A. , Kuchinsky V.I. , Mizerov M.N. , Portnoy E.L. , Reich M.E.
Published: February 2023

The interest to second order DFB semiconductor lasers is due to the difraction grating imbedded on the waveguide laser surface serving not only as a resonator, but also serving for the first order narrow-directed output of generated radiation, the latter being perpendicular or at a small angle to the active layer plane [1,2]. However, such radiation output not only improves the radiative device characteristics, but also helps to obtain direct experimental information about the physical processes in DFB lasers. A good example of this is the experimental discovery of a new type of distributed feedback in a multimode active waveguide – skip DFB generation – which is stipulated by grating coupling of radiation from a mode with one transverse number back into the mode with another transverse number[3].
Focal Properties of Uncorrected Geodesic Waveguide Lenses*
Authors: Vahey D. W. , Verber C. M. , Wood V. E.
Published: February 2023

In recent years a number of researchers have developed a wide variety of lenses for integrated optics.1 We report on our efforts to extend this area of research to the applications stage by evaluating the quality of geodesic waveguide lenses and using such lenses to perform one-dimensional Fourier transformations.
Switched Directional Coupler with Stepped Δβ-Reversal
Authors: Kogelnik H. , Schmidt R. V.
Published: February 2023

It has been proposed1,2 that optical directional couplers with dielectric waveguides fabricated in electro-optic material and controlled by an applied electric field can serve as amplitude modulators or as switches of information-carrying optical channels. In principle, the switching function can be obtained by control of either the coupling (κ) between the two waveguides or of the difference Δβ in the two propagation constants (phase mismatch), but it was soon recognized3-6 that the control of phase mismatch is preferable as it requires drive voltages that are about 2 orders of magnitude smaller. Recently, Papuchon et al7 and Campbell et al8 have reported the first implementations of such devices using diffused strip guides in LiNbO3 and metal-gap strip guides in GaAs, respectively. These first devices may perform well as amplitude modulators, but it still appears difficult to produce optical switches that can meet the stringent cross-talk requirements demanded by the various communication systems, namely some 25 to 70 decibels depending on the application. One of the reasons for this difficulty is the fact that the Δβ-switched directional coupler allows the electrical adjustment of only one of the two switching states. As a step toward easing this difficulty, we propose here a modified switched coupler configuration, which allows the electrical adjustment of both switching states. This property is obtained by constructing a coupler consisting of two sections with phase mismatch Δβ of opposite sign.
Planar Branching Networks for Multimode and Monomode Glass Fiber Systems
Authors: Auracher F. , Boroffka H. , Kersten R. Th.
Published: February 2023

In glass fiber communication systems the need arises for distributing optical signals from one incoming to several outgoing glass fibers. Very little has been published /1/ with regard to this problem. If the coupling problem of monomode glass fibers to strip waveguides is solved satisfactorily such distribution networks can be realised by means of integrated optical components, i.e. either by means of directional couplers or by simple branching waveguides together with tapers. In the case of multimode glass fibers with core dimensions typically around 100 μm the standard processes for integrated optics are no longer well suited if one tries to butt join the glass fiber to the integrated optical strip waveguide. The strip waveguide would then have to be ≈ 100 μm thick which is difficult to achieve with the standard processes for waveguide fabrication in integrated optics, namely sputtering, evaporation or ion implantation. Also the standard photoresists required for pattern definition are only usable up to it ≈ 5 μm thickness.
Low-loss Infrared Guiding in Metal-Dielectric Waveguides
Authors: Garmire E. , McMahon T. , Bass M.
Published: February 2023

The low infrared loss of TE modes in planar metallic waveguides has already been pointed out.1 Our interest is to develop low-loss infrared two-dimensional waveguides. As a first step in this development, we consider the infrared losses in a rectangular metallic waveguide of height a and width b. The loss induced by the metallic sidewalls is high, unless the waveguide is very wide.
Self-Imaging in Homogeneous Optical Waveguides
Authors: Ulrich R.
Published: February 2023

When an object is placed against one end of an optical waveguide, a real optical image (self-image) of it may be formed at the other end under certain conditions (Fig. 1). In wave-optical terms, these conditions require the phase differences ψjk=(βj−βk)L between any two excited modes at the end of the guide to be integral multiples of 2π. Here, βj denotes the propagation constant of the j-th mode, and L is the length of the guide. Under these conditions, the interference of the modes in the exit plane of the waveguide is the same as in the entrance plane, and a real image is formed. While it is long known that such an image transmission is possible with guides having a square-law index profile, the imaging property has recently also been demonstrated for planar guides with homogeneous refractive index.1,2 The planar guide provides only one-dimensional (line ↔ line) imaging in the same sense as a cyclindrical lens. The corresponding two-dimensional (point ↔ point) imaging is possible with dielectric guides of rectangular or square cross-section. In the present paper, these self-imaging processes in guides of homogeneous index are discussed theoretically, and experimental results are presented illustrating this phenomenon.
Wave Characteristics of Bends in Dielectric Guides
Authors: Heiblum M. , Harris J. H.
Published: February 2023

Bends play a central role in the design of integrated optical systems, for example in isolation of the output arms of a directional coupler, modulator, or switch. Introduction of a bend in a guide results in a redistribution of energy toward the outside of the bend as well as continuous radiation from the structure. There are also transition losses at input and output planes of the bend. Approximations for the radiation losses for bends, described geometrically as arcs of circles, have been obtained previously for arcs of large radius of curvature.1 More recently it has been shown2 that the application of conformal transformations to the analysis of waveguide bends can lead to relatively simple approximate expressions for guide parameters for arcs of arbitrary radius of curvature. In this paper we present numerical results obtained from the conformal-transformation based analysis on a guide formed by a step increase in refractive index over a region of arbitrary thickness, and on a guide generated by a single step change in refractive index when the surface of the higher index region is convex. As a result of a logarithmic conformal transformation W=RℓnZ/R, the boundaries of a guide with arcs as boundaries in the x-y plane become parallel straight lines in the u-v plane. The index of refraction varies as n exp(u/R) in the transverse direction (u) and remains constant along the coordinate v which is the direction of propagation in the transformed planar configuration, and nor mal to u. The terms W and Z in the above transformation represent the complex values u+iv and x+iy respectively and R is the radius of some circle in the x-y plane.
Recent Development On High Power Infrared Waveguide Modulators*
Authors: Cheo P. K. , Wagner R.
Published: February 2023

This paper presents the latest development on the high-power infrared waveguide modulator which takes the advantages of both the integrated optics and microwave microstrip technologies. When fully developed this subcarrier broadband traveling-wave waveguide modulator will be the first practical thin-film device to be used in the high-resolution optical imaging radar system. Recently several significant advances have been made on this modulator device, particularly in the area of improving the waveguide quality, which is essential for both the optical and microwave performance. This paper discusses the fabrication techniques that yield low-loss GaAs single-crystal thin-slab waveguides with an electro-optic interaction length greater than 3 cm. Also discussed in this paper is the optical transmission characteristics. We have obtained more than 3 watts transmitted CO2 laser power in a Gaussian beam through a 2.8 cm long (excluding the lengths of couplers) metal claded waveguide modulator having a thickess of ≃25 μm, by using a 6 watts CO2 laser as the input.
Visualization of Integrated Optical Microcircuits by Fluorescence
Authors: Roy A.M. , Sejourne-Puech B.
Published: February 2023

In parallel to the important progress made in many laboratories (1,2) in the realization of microstructures for integrated optics, we have developed a method to visualize optical fields propagating in these structures, based on the examination of the fluorescence emitted by a film deposited on these guides (3).
Second Harmonic Generation in Composite Waveguides
Authors: Zernike F.
Published: February 2023

Second harmonic generation in optical waveguides has been demonstrated using (1) a nonlinear guide and substrate,1 (2) a nonlinear guide on a linear substrate,2 (3) a linear guide on a nonlinear substrate with the harmonic coupled back into the guide,3 and (4) a linear guide on a nonlinear substrate with the harmonic generated as Cerenkov radiation.4
Channel Waveguide Electrooptic Devices for Communications and Information Processing
Authors: Taylor H. F. , Martin W. E. , Caton W. M.
Published: February 2023

Wide bandwidth and improved switching are expected to be the most important advantages of using integrated optics components and single- mode fibers for Navy communications. It was recognized several years ago that the practical realization of these advantages would require a sizable research and development effort. A program was initiated to solve the critical problems in several areas: injection laser sources, waveguide couplers, modulators, switches, electronic drivers, and receivers. Progress in each of these areas is described below.
Corrugated Grating Coupled Devices and Coupling Coefficients
Authors: Zory P.
Published: February 2023

Marcuse has used local normal mode theory to calculate general expressions for the coupling coefficients (distributed leakage - DL and distributed feedback - DFB) for asymmetric slab waveguides with corrugated core boundaries.1 This approach and in general most approaches to this problem2,3,4 do not give one much feeling for the workings of the diffraction process and are limited in their ability to handle deep and/or metallic groove configurations where higher order diffraction effects can be important.5 In this paper, a simple ray optics6 technique is outlined which can be used to find approximate values for coupling coefficients in such configurations. In essence, the corrugated waveguide is separated into a planar waveguide and a diffraction grating and each problem is solved separately. The individual solutions are then combined in a manner consistent with the bounce picture of mode propagation. The validity of the technique is proven in the shallow dielectric groove domain by comparing closed form expressions for the DL and DFB coefficients of a sinusoidally corrugated waveguide to the numerical results given in references 2, 3 and 4.
Evaluation of Large-Area GaAsP Heterostructure Waveguides for 1.06 μm and 0.905 μm Wavelengths*
Authors: Sopori B. L. , Chang W. S. C.
Published: February 2023

The successful performance of large-area GaAs/GaAs1-xPx heterostructure waveguides, as demonstrated earlier, at 10.6 μm wavelength has prompted us to investigate the propagation characteristics of these waveguides at 1.06 μm and 0.905 μm wavelengths.1,2 To be useful at these wavelengths, it is necessary to reduce the film thickness to 1-2 μm and ensure good surface quality at both air/film and film/substrate interfaces. Further, in order to be useful at 0.905 μm, the band-edge absorption must be reduced. Addition of phosphorus into GaAs epitaxial film is expected to reduce the band-edge absorption by shifting the absorption edge to a shorter wavelength. However, the effect of strain induced by lattice mismatch between the film and the substrate may tend to broaden the absorption edge.
Grating Coupled GaAs/GaAℓAs Ring Laser
Authors: Scifres D. R. , Burnham R. D. , Streifer W.
Published: February 2023

We report output coupling of guided modes in an electrically pumped GaAs/GaAℓAs ring laser. The device which utilizes a grating coupler1-5 has the advantages of low laser threshold, which is characteristic of diode ring lasers, and of highly collimated, polarized output beams.
Radio Aperture Synthesis
Authors: Sramek R.A.
Published: February 2023

The history of radio astronomy is very much a history of the pursuit of higher resolution. The angular scale of cosmic radio emission ranges from tens of degrees in the continuum emission of our Galaxy down to submilliarc-second structure in the cores of distant radio galaxies and quasars. Single apertures observing at centimeter wavelengths can only provide resolution of a few arc-minutes. Radio astronomers quickly turned to interferometer arrays to study the more compact cosmic radio sources [1-6].
Improving on Pinholes in Stellar Interferometers
Authors: KenKnight Charles
Published: February 2023

We want to improve imaging through the turbulent atmosphere. At the entrance pupil the object spectrum is color dependent, but the projection of the atmosphere is barely so. This situation is reversed in the focal plane, so the optimum approach measures the atmosphere with a broad band of light in the pupil such that the object is sensed as little as possible. Then the object information is extracted from the focal plane (F.P.) measures. Nevertheless, simultaneous measures with two first-rate area detectors are expensive, so we here emphasize what can be done with one F.P. area detector.
Adaptive Optics in Radio Astronomy
Authors: Cornwell T.J.
Published: February 2023

Adaptive optical imaging systems [1-8] have not made a significant impact in optical astronomy but, in the guise of selfcalibration or hybrid mapping [13-19], have revolutionised both very long baseline radio interferometry, in that true image formation was made possible, and short baseline interferometry, dramatically improving the dynamic range attainable. Unfortunately, radio astronomers tend to use their own specialised jargon and to publish in their own journals; for this reason specialists in other fields may not be aware of recent work. In this review paper I will attempt to explore the concepts common to all "adaptive opticians" and to translate unfamilar jargon.
Data Analysis for the Space Telescope
Authors: Albrecht R.
Published: February 2023

This paper addresses the problems of analysis of large volumes of multidimensional data using the example of the data analysis facility currently being developed at the Space Telescope Science Institute.
Two-Dimensional Image Reconstruction Algorithms
Authors: Fienup J.R.
Published: February 2023

In both optical and radio astronomy, sometimes one can accurately obtain the modulus of the Fourier transform of an image, but not the Fourier phase. In order to obtain an image then it becomes necessary to solve the Fourier phase retrieval problem. Since the autocorrelation can be computed as the Fourier transform of the squared Fourier modulus, the problem is equivalent to reconstructing an image from its autocorrelation.
An Astronomical Image Processing System for Arizona State University
Authors: Whitmore Bradley C. , Wyckoff Susan , Wehinger Peter A.
Published: February 2023

We have recently acquired a DEC VAX 11/730 computer with partial support from an International Halley Watch grant from NASA/JPL. The VAX 11/730 has a 1 Mb CPU with a floating-point processor. We hope to expand the CPU to 4-5 Mb in the next year. Peripherals include two disk drives: DEC RL02 (10.4 Mb) and an R80 (121 Mb). The VAX/VMS Version 3.1 operating system takes up about 25 Mb on the R80 disk drive. Fortran 77 has. also been added. System up-dates and software drivers are added via a TU58 tape cassette drive. At present, we have one 9-track tape drive, a Kennedy Model 9100, which runs at 75 inch/sec on 800 or 1600 bpi. We have two VTl00's with Retrographics (emulating the Tektronix 4010). An LA120 (Decwriter III) serves as a operating console and printer (180 characters/sec). In addition, we have a Versatec V-80 printer-plotter.