bluuebunny/crossref_metadata_2025 huggingface dataset:
Maps of Eta Carina at Six Wavelengths Between 8 and 13 Microns
Authors: Hackwell J. A. , Grasdalen G. L. , Gehrz R. D.
Published: February 2023

During January, 1981, the CT10 4-m telescope was used with a 6-detector bolometer array spectrometer (Gehrz, Hackwell, and Smith, 1976, P.A.S.P., 88, 971) to make maps of Eta Carina simultaneously at wavelengths of 8.1, 8.9, 10.2, 11.3, 12.2 and 13.1 microns, with a 1.8 arcsec FWHM beam. The maps were made using a fast raster scanning method (Grasdalen, et. al. Bull. A.A.S., 11, 712; Hackwell, Grasdalen, and Gehrz, 1982, Ap. J., 252, 250) in which the wobbling secondary mirror is stepped in declination under computer control, while chopping, to produce a scan line. After each scan line, the telescope is stepped by one pixel in right ascension to build a map. The measured intensity of each pixel is taken to be the difference between the signal beam and the displaced reference beam. For this project, we scanned a 32 × 32 raster centered on Eta Carina with a 0.8 arcsec pixel spacing, and an integration time per pixel of 0.4 seconds. Four frames were co-added to reduce high spatial frequency noise due to seeing, giving an overall integration time per pixel of 1.6 seconds and a final signal-to-noise ratio in the brightest regions of 500 at 13.1 microns and 2000 at 11.3 microns. Absolute calibration and beam profiles were determined by mapping standard stars from the list of Elias et. al. (1983 A. J., in press) at the same pixel spacing and chopper throw as for Eta Carina. Our measurements give integrated fluxes which agree well with those determined by other observers (e. g. Gehrz et. al. 1973, Ap. Lett., 13, 89).
Some results of bidimensional spectroscopic observations of solar active regions and flares.
Authors: Caccin B. , Donati-Falchi A. , Falciani R. , Roberti G. , Smaldone L.A.
Published: February 2023

Bidimensional spectroscopy of solar chromospheric structures has been performed at the Sacramento Peak Observatory (SPO) for a collaborative study of active regions and flares together with radio and space-born NASA—SMM observations within the framework of the Solar Maximum Year activities.
Astronomical Data Processing from the MEPSICRON Photon Counter
Authors: Firmani Claudio , Paresce Francesco
Published: February 2023

Very recently a new detector, the MEPSICRON (Microchannel Electron Position Sensor with time resolution), has been developed with the purpose of overcoming the limitations of the sweep read out photocounter. The MEPSICRON works in the photon counting regime and can be described as a position sensitive photomatrix tube. A simple description of this instrument is given by Firmani et al., 1982. The MEPSICRON internal noise is given basically by the shot noise of the photocathode. The electron and ion dark current is very low and in most cases completely irrelevant. The total number of pixels, i.e. the number of spatially resolved locations, is 8×105 for the circular surface of 25 mm of diameter of the tube.
Solar Spectroscopy On Two Dimensional Fields
Authors: Cavallini F. , Ceppatelli G. , Falciani R. , Righini A.
Published: February 2023

Solar spectroscopy on two dimensional fields is strongly needed to obtain a better understanding of the physical processes which take place in chromospheric and photospheric plasmas. Up to now several devices have been used to obtain strictly monochromatic imaging of solar surface, however difficulties arise when the knowledge of the instrumental spectral passband is required for a detailed physical analysis of the images or/and when careful wavelength setting of the passband central peak must be assured at several precise wavelengths (Caccin et al., 1978; Azzarelli et al., 1979; Caccin and Roberti, 1979).
Activities of the modeling working group of the European Cost-216 project
Authors: Lagasse P. , Franssens G. , Vankwikelberge P.
Published: February 2023

Working group I of the European Cost-216 project on optical switching is active in the comparison of numerical methods for the modeling of integrated-optic waveguide structures. The results of a first problem set consisting mainly of the calculation of the modal properties of single and coupled waveguides have now been published.1 The intermediate results obtained in the past year for a second problem set will be presented. This second problem set consists of various integrated-optic waveguide S bends, including features such as offsets. Complete coupler structures, including input and output waveguides are also considered. Results of more than 10 different European groups, using a variety of numerical methods, are currently considered. Probably the most challenging aspect of the exercise is the fact that for most of the problem set accurate experimental results are available. This means that a study is possible of the agreement not only between the various modeling methods, but also between the theoretical and experimental results. In the last case it is interesting to compare both the variation of, for example, the bend loss as a function of radius and the absolute value of that loss. From the results obtained so far, it is obvious that a lot of work remains to be done before the currently available modeling methods can be used as reliable computer-aided design tools.
Single-mode nonlinear polymer channel waveguides using a photopolymer cladding technique
Authors: Ashley Paul R. , Tumolillo Thomas A.
Published: February 2023

Polymer films have been the object of renewed research as organic polymers with large second-order nonlinearities are becoming available. One of the remaining problems for waveguide applications is the development of suitable cladding materials for optical confinement in channel waveguides.1-4 These materials must be capable of being easily fabricated into thin films and patterned for low-loss waveguide construction with design flexibility. Reported here is the fabrication of single-mode channel waveguides/phase modulators using a photopolymer projection printing technique.
Mirror-folded polarization-independent tunable-wavelength filter
Authors: Heismann F. , Divino M. D. , Buhl L. L.
Published: February 2023

We demonstrate a 1.55-μm polarization-independent wavelength filter with a 3-dB bandwidth of only 6 Å and an electro-optic tuning range of more than 100 Å. The filter is fabricated on x-cut LiNbO3 and features a novel electro-optic TE ï TM mode converter with electrically adjustable TE–TM output phase.
Reducing radiative loss from intersecting waveguides by fractional doping
Authors: Gill Douglas M. , Agrawal Niraj , McCaughan Leon
Published: February 2023

Intersection waveguides are now a fundamental waveguiding structure for integrated optics. It has, therefore, become essential to find an accurate predictive theory or model for this geometry. Electro-optic switch arrays, for example, have been demonstrated by using this waveguide configuration, but insertion losses limit the performance of large arrays.1 A recently developed theory based on a multiple scattering analysis has, for the first time, correctly predicted both the coupling and the radiative loss behavior for intersecting waveguides.2,3 In this theory radiation loss can be represented by a coupling coefficient between guided and radiation modes of the waveguides. The contribution to this coupling coefficient from the waveguide arms and the intersection region can be made to interfere destructively, dramatically reducing the light coupled from guided to radiation modes.4 By adjusting the permittivity of the intersection region the relative magnitudes of the two coupling coefficients can be adjusted, thereby lending a processing degree of freedom with which to minimize radiative losses without restricting design parameters such as intersection angle.
20-GHz Ti:LiNbO3 optical modulators employing new traveling-wave electrode systems
Authors: Kawano Kenji , Nozawa Toshinori , Jumonji Hiromichi
Published: February 2023

External optical modulators are attractive for high-speed transmission systems. A Ti:LiNbO3 optical modulator1-8 is one of the most feasible among them. However, the realization of both wide-band modulation and low driving voltage remains to be developed.
Semiconductor-grafted integrated optics
Authors: Yi-Yan A. , Chan W. K. , Gmitter T. J. , Seto M.
Published: February 2023

Epitaxial lift-off can be effectively used to transfer thin-film semiconductor layers from their parent substrate to foreign substrates that are not necessarily made of semiconductor material.1 The transferred films are bonded, without glue, to the target substrate by van der Waals forces. The potential of this technique is greatly enhanced by grafting semiconductor layers directly onto substrates with optical waveguide circuits and, additionally, by establishing optical interaction between the two.
Color-center model for second-order optical nonlinearities in germanosilicate optical fibers
Authors: Poyntz-Wright L. J. , Russell P. St. J.
Published: February 2023

Second-order nonlinearities can be induced in germanosilicate (GS) glass fibers in a variety of ways: by coherent superposition of pump and second-harmonic light (a third-order dc polarization Pdc3 is induced that breaks the inversion symmetry1); by excitation poling with blue light and an external dc field,2 Epol; and by strong Epol’s in the absence of light.3 There is as yet no satisfactory agreement over the nature of the underlying alignment process. From related detailed studies of color-center behavior in GS fiber,4 we have formulated a self-consistent model as developed in the following points.
Annealed Erbium-implanted single-mode LiNbO3 waveguides
Authors: Brinkmann R. , Buchal Ch. , Mohr St. , Sohler W. , Suche H.
Published: February 2023

We report the first Erbium-doped single-mode LiNbO3 waveguides, which are promising candidates for optical amplifiers and lasers in the 1.5 < λ < 1.6μm wavelength range.
1.3-μm InGaAs/GaAs interdigitated metal–semiconductor–metal photodetectors
Authors: Jagannath C. , Masum Choudhury A. N. M. , Elman B. , Armiento C. A.
Published: February 2023

The development of monolithic optoelectronic integrated circuits (OEICs) are of considerable interest because these components are expected to offer increased reliability, lower cost, and higher speed than their hybrid counterparts. Of particular interest in future broadband communication systems is the integration of long-wavelength (1.3–1.6 μm) optoelectronic devices with high-speed electronic circuits. Recent advances in heteroepitaxial growth of lattice-mismatched materials has made it possible to grow epitaxial InGaAs on GaAs substrates. This technology offers the possibility for fabrication of InGaAs interdigitated metal–semiconductor–metal (IMSM) photodetectors, operating at a wavelength of 1.3 μm, on GaAs substrates.1 Compared with lattice-matched growth on InP, growth on GaAs offers the potential for exploiting the mature GaAs electronics technology in the development of monolithic receiver OEICs. IMSM photodetectors have a planar geometry that simplifies integration with GaAs MESFETs. Monolithic integration, however, requires that the epitaxial InGaAs be able to withstand MESFET processing such as high-temperature anneals used to activate ion-implanted layers.
Solitons in coupling structures
Authors: Wabnitz S.
Published: February 2023

In addition to the interest in them for coding information in high-bit-rate time-division multiplexed optical communication systems, solitons are attractive for use in all-optical processing devices. Indeed, the uniform phase shift of solitons has been exploited for femtosecond pulse self­switching in fiber interferometers.
Four-channel wavelength demultiplexer using polymer microstructure waveguides
Authors: Wang M. R. , Chen R. T. , Sonek G. J. , Jannson T.
Published: February 2023

Wavelength-division multiplexing and demultiplexing is recognized as a powerful means for increasing the channel density and bandwidth of data transmission and processing systems.1 Herein, we report on the development of a new four-channel integrated-optic wavelength-division demultiplexer, using multiplexed waveguide holographic gratings patterned on a locally sensitized single-mode polymer (photo-lime gelatin) microstructure waveguide.
Polarization anisotropy of a 1.52-μm InGaAs/InP multiple quantum-well waveguide absorption modulator
Authors: Pappert S. A. , Orazi R. J. , Vu T. T. , Clawson A. R. , Lin S. C. , L Yu P. K.
Published: February 2023

Optical waveguide modulators operating at 1.5-μm wavelength are important optoelectronic devices that can be used to extend the bandwidth-distance capacity of optical fiber transmission systems. Multiple quantum-well (MQW) absorption type waveguide modulators fabricated in InP substrates and operating near 1.5-μm wavelength have been demonstrated1-4 by using various material and growth systems. Previous experimental work on 1.5-μm MQW waveguides has primarily examined the modulation performance of TG polarized light (light polarized parallel to the MQW layers); not as much attention has been paid to the TM polarization. For an InGaAs/InAlAs MQW waveguide modulator, the polarization dependence of the electroabsorption has been reported5 with similar modulation performance for both polarizations. In this paper an In0.53Ga0.47As/InP (from nowon referred to asInGaAs/InPridge-waveguide MQW absorption modulator is described at an operating laser wavelength of 1.52 μm. In contrast to previous work5 the modulation performance of the TM polarization is found to be superior to that of the TE mode. Experimental data showing optical absorption saturation of this device for both polarizations is also presented.
Interferometric technique for accurate measurement of the mode indices of channel waveguides
Authors: Hussell Christopher P. , Ramaswamy Ramu V. , Srivastava Ramakant
Published: February 2023

An accurate measurement of the difference in the propagation constant between two modes is essential in the design of several devices. For example, tapered velocity couplers1 or cross couplers2-4 require adiabatic transitions, and an accurate knowledge of the propagation constant of each of the two individual waveguides is, therefore, necessary. Prism couplers are often used for measurement of the mode indices to moderate accuracies. However, buried guides cannot be characterized by using the prism coupler. In this paper we demonstrate the use of a Mach-Zehnder interferometer to measure differences in mode indices between modes in different waveguides with an accuracy of 1 x 10-4 or better. The technique can also be used to determine absolute value of the mode index in cases where waveguides near cutoff are available on the same substrate.
In-line flexural wave optical modulator, filter, and frequency shifter in dual-core fiber
Authors: Sabert H. , Dong L. , Russell P. St. J.
Published: February 2023

A component vital to the successful implementation of single-mode fiber signal processing and communications systems is an integrated in line Bragg cell that can function as a modulator, SSB frequency shifter, and tunable WDM tap. A number of reported devices1,2 go toward achieving this goal, the most efficient to date being the flexural-wave modulator in a dual-mode single-core (DMSC) fiber developed by Kim et al.2 In their device the LP11 and LP01 normal modes (NMs) of the DMSC structure are coupled together by an acoustic flexural wave whose wavelength matches the intermodal beat period. Launching light into the even mode results in a frequency-shifted signal in the odd mode. In practice, however, it is difficult to excite just one NM, and a frequency-shifted signal in the LP11 mode is not appropriate for efficient pigtailing to a single-mode fiber. The dual-core (DC) device we have developed avoids these problems by permitting low-loss fusion splicing of a single-mode fiber to either core and having negligible intrinsic coupling. This is achieved by designing the DC to be phase velocity mismatched to such a degree that the NMs of the DC coupler are almost identical to the modes of each core in isolation. Provided that there is sufficient overlap of the modal fields, distributed feed-forward NM (and hence intercore) coupling will be achieved3 in the presence of a flexural wave at the correct frequency. We fabricated two different DC fibers, DC1 and DC2, with experimentally determined beat lengths of 0.43 mm and 1.205 mm, respectively at λ = 1μm. Flexural waves were excited by using fused silica horns bonded to the DC fibers with glass solder. The intrinsic coupling in DC1 was too small to measure with our setup, and 8.5% acousto-optical coupling was obtained at 4.6 MHz and 962.5 nm. The instrinsic coupling of the DCS was approximately 4%, and 100% (and beyond) acousto-optical coupling was achieved at 560 kHz and 1.064 μm. The length of DC fiber in each case was 30 cm. Both devices were widely tunable. The results of a heterodyne experiment with DCS, illustrated in Fig. 1, are presented in Fig. 2. The high intrinsic coupling of DC2 meant that the carrier was not fully suppressed, and the 9 cm of fiber on the opposite side of the horn meant that sideband suppression was not perfect. We believe that with additional development the modulator has considerable potential as a practice device.
The meeting problem set
Authors: Hawkins Raymond J.
Published: February 2023

To stimulate and facilitate comparisons of various numerical techniques, the subcommittee on modeling, numerical simulation, and theory prepared a set of waveguide modeling problems. A summary of submitted results will be presented.
Finite-element full vectorial analysis of anisotropic optical waveguides
Authors: Zoboli Maurizio , Bassi Paolo , Lubian Nicola , Someda Carlo G.
Published: February 2023

The finite-element method (FEM), although in principle being powerful for analyzing numerically optical waveguides, can in practice be limited by several factors. It is well known that its scalar versions are often not accurate enough, particularly if we are dealing with anisotropic media. If one exploits a vector functional, the number of triangular elements in the mesh can become an unacceptable limiting factor when the computer memory is not large enough. At the same time, fine details of the mesh can play an important role, but their careful preparation on a large computer can imply an unacceptably large waste of time and money.
Theoretical aspects of intermodal couplers in photosensitive optical fibers
Authors: Ouellette François
Published: February 2023

When a Ge-doped fiber is irradiated with intense visible light launched simultaneously in two different modes, the beating of the modes induces a permanent refractive-index grating through the photosensitivity of the fiber.1,2 This grating subsequently permits mode coupling at the irradiation wavelength between the two writing modes but also between other modes at different wavelengths, provided that phase matching is satisfied i.e., that the beating period of the modes is the same as that of the grating.3 The refractive-index change for this type of grating is not a constant across the core of the fiber but depends on the transverse coordinates τ and ϕ. From the expression of the coupling coefficient, we find that mode coupling is permittted only if the modes satisfy specific selection rules. For example, a grating written with the x-polarized LP01 and LP11even modes has a cos ϕ dependence and will not couple the x-polarized LP01 and LP11odd modes at a wavelength different from the irradiation wavelength, since the x- and y-polarized LP11even modes have slightly different propagation constants. This is true even in a circular fiber, where one must consider the exact nondegenerate EH and HE modes. Therefore the mode coupling depends on the polarization and on the wavelength of the incident light. Mode coupling can also be allowed between modes having a different transverse profile from that of the writing modes, and there are different possibilities of obtaining phase-matched mode coupling in the IR (e.g., at diode laser wavelengths) when using a grating written with visible light around 500 nm, where the photosensitivity of the fiber is strongest.3 Mode coupling is also allowed if the refractive-index change is constant across the core but only between modes having the same value of l, i.e., they have the same angular dependence. It is therefore possible to induce an intermodal coupler by externally exposing the fiber to periodic UV light, as was done for Bragg gratings.4
Basic operation mechanisms of phase-front accelerators
Authors: Chan H. P. , Chung P. S. , Pun E. Y. B.
Published: February 2023

Although branching waveguides are essential components in integrated-optical systems, devices using Y junctions suffer from radiation losses, particularly abrupt-bend structures with relatively large branching angles. Tsutsumi et al. showed that the transmitted power will deteriorate rapidly as the branching angle increases above 1°, owing to the strong mode conversion between guided and radiation modes.
Properties of quasi-phase-matching lithium niobate waveguides
Authors: Laurell F. , Webjörn J. , Arvidsson G.
Published: February 2023

Quasi-phase-matching channel waveguides have been fabricated in LiNbO3. The fabrication procedure is based on outdiffusion-induced periodic domain inversion followed by waveguide fabrication by the annealed proton exchange technique.1 Such waveguides have previously been used for second harmonic generation1 and we now report further investigations of their properties.
All-optical phase modulation in PTS-polydiacetylene waveguides
Authors: Thakur M. , Krol D. M.
Published: February 2023

Polydiacetylenes are well known as materials having large nonresonant third-order susceptibilities. We have measured phase changes in PTS-polydiacetylene channel waveguides as a function of optical intensity using Mach-Zehnder interferometric method. The results are highly encouraging in terms of all-optical device applications of the material.
Integrated-optic laser fabricated by field-assisted ion exchange in neodymium-doped soda-lime silicate glass
Authors: Sanford N. A. , Malone K. J. , Larson D. R.
Published: February 2023

The use of rare-earth doped optical fibers for amplifier media and specialty lasers has recently attracted considerable attention.1 Integrated optics offers a natural extension to the concepts of rare-earth doped waveguide technology with the advantage of multiple device fabrication of planar and channel structures on a single substrate. Ion implantation has been used to form a waveguide laser in Nd:YAG.2 Silver ion exchange was demonstrated to produce waveguides in lithium-silicate laser glass3 but laser action was not reported.
Neodymium-doped silica optical waveguide laser on silicon substrate
Authors: Hibino Yoshinori , Kitagawa Takeshi , Shimizu Makoto , Sugita Akio , Ohmor Yasuji
Published: February 2023

Recently, we have demonstrated cw lasing of a Nd-doped silica waveguide fabricated on Si substrates.1 Compared with fiber lasers,2 the waveguide lasers on Si substrates have the advantage for integration of optical and electrical components. In this paper we examine lasing characteristics of the Nd-doped waveguide lasers to show the possibility of laser-diode (LD) pumping.
Single-mode Ti-diffused optical strip guides and lasers in Nd:MgO:LiNbO3
Authors: Brinkmann R. , Sohler W. , Suche H. , Wersig Ch.
Published: February 2023

For the first time, to our knowledge, fluorescence and laser oscillation in Ti-diffused waveguide structures in Nd:MgO:LiNbO3 samples are reported. The Ti-indiffusion technique was used to study an alternative to the proton exchange technique which has been applied for the recent development of the first guided wave laser in LiNbO3.3Ti-doped amplifier and laser structures would be compatible to the numerous Ti-diffused devices in LiNbO3 already developed.
Four-channel wavelength-division multiplexers based on elliptical Bragg reflectors
Authors: Kazarinov R. F. , Henry C. H. , Shani Y. , Kistler R. C.
Published: February 2023

Combiners and splitters for WDM have been made by various implementations. A favored approach using bulk optics has been to fabricate a miniature spectrometer with a blazed grating.1,2 An integrated version of this device was demonstrated by Valette.3
Acoustic-mode analysis of multilayered structures
Authors: Armenise Mario N. , Passaro Vittorio M. N. , Impagnatiello Fabrizio
Published: February 2023

The acousto-optic transducer (AOT) is a fundamental component of a number of hybrid circuits for optical computing and optical signal processing. The grating created by the surface acoustic wave (SAW) in an AOT generates Bragg diffraction of an incident optical wave, and the intensity of the diffracted wave is proportional to the product of the incident light intensity and the power of the acoustic wave. This fundamental property of AOTs is widely used for spectral analysis and correlation of wide-band signals. Therefore, the theoretical analysis of an AOT involves both the optical and acoustic modal investigation. In most applications the role of the optical mode analysis is predominant over the acoustic mode analysis because the SAW propagation speed does not depend on the acoustic frequency, as occurs in the LiNbO3 devices.
Characteristics of low-propagation-loss LiTaO3 optical waveguides proton exchanged in pyrophosphoric acid
Authors: Li Yu-Shan , Yuhara Toshiya , Tada Kunio , Sakaguchi Yasuyuki
Published: February 2023

Proton-exchanged LiTaO3 waveguides1 fabricated by both simple one-step proton exchange2 and similar proton exchange followed by annealing3 in benzoic acid were reported to have a negligible decrease in the r33 electro-optic coefficient. It was also reported that the propagation loss was reduced in pyrophosphoric acid proton-exchanged LiNbO3 waveguides.4
Measurement of the electrically induced refractive-index change in silicon for wavelength λ = 1.3 μm by using a Schottky diode
Authors: Evans A. F. , Hall D. G.
Published: February 2023

Silicon is a centrosymmetric crystal, so it does not exhibit a Pockels (linear electro-optic) effect. It does, however, exhibit a free-carrier effect in which both the real and the imaginary parts of the refractive index are changed when carriers are introduced either through doping or injection. Demonstrations of the use of the free-carrier effect in silicon include direct amplitude modulation from carrier injection in a forward biased p-i-n (Ref. 1) or MIS (Ref. 2) diode as well as amplitude modulation from a phase shift in a 2 × 2 switch3 and an interferometric modulation scheme.4 These investigations required large current densities (greater than 100 A/cm2) to achieve modulation of 10%-60%. Furthermore, the size of the real index change was not reported.
Large refractive-index change by carrier injection in multiquantum-well waveguides
Authors: Tanaka Kazuhiro , Wakao Kiyohide , Fujii Takuya , Soda Haruhisa , Yamakoshi Shigenobu
Published: February 2023

Devices using refractive-index change such as lasing wavelength selection1 or conversion2 are indispensable to establish wavelength-division optical systems. For these devices, layers whose refractive index changes greatly are favorable to obtain large operating wavelength width.
Computer-aided analysis of semiconductor lasers-MINILASE
Authors: Song G. Hugh , Hess Karl
Published: February 2023

Stimulated by recent developments in optical communication technology, we have developed a versatile two-dimensional simulator for various types of semiconductor lasers for both steady state and transients. The simulator, called MINILASE, is capable of spectral analysis of single and multiple quantum-well lasers and also analyzes the internal two-dimensional temperature distribution as well as current flow and optical intensity patterns.
Two-dimensional analysis of InGaAsP/InP intentionally reverse-biased buried heterostructure lasers
Authors: Seki Shunji , Yamanaka Takayuki , Kurumada Katsuhiko
Published: February 2023

InGaAsP/InP buried-heterostructure (BH) laser diodes play a significant role in long-haul optical transmission systems. Recent requirements for InGaAsP/InP lasers with light output of more than tens of milliwatts have led to the need for BH structures that have an ultimately low leakage current under high-current operation. Although the current leakage mechanism in conventional BH structures of which buried region consists of p-n-p-n structure has been extensively studied,1 the basic design principles for lowering leakage current under high-current operation have not been clarified yet.
Numerical analysis of the absorption and refractive index in arbitrary semiconductor quantum-well structures
Authors: Nakamura Kenji , Shimizu Akira , Fujii Kazuhito , Koshiba Masanori , Hayata Kazuya
Published: February 2023

We present a numerical method for the analysis of the absorption spectrum and the refractive index in semiconductor quantum-well structures (QWSs) with arbitrary potential profiles. The validity of the method is confirmed by comparing the numerical results for a rectangular quantum well (QW) with the experimental results. We also demonstrate the noteworthy results for an asymmetric double-QW structure.
Rare-earth-doped fibers
Authors: Snitzer Elias
Published: February 2023

With the availability of compact high brightness laser diodes as pumps and low loss glasses as the hosts for rare earths, a significant new category of lasers has emerged. The small diameters for single mode fibers gives high thermal gradients that readily dissipate any heating so as to allow CW operating for outputs as high as several watts. The greatest attenuation has been given to erbium in silica operating at 1.53-1.55 μm as an optical amplifier for communications. It gives gains approaching 40 dB, gain coefficients greater titan 5 dB/mW for pumping at 0.98 or 1.47 nm, and saturation outputs of 18 dBm in fibers that are readily compatible with commercial fibers. In a double clad silica fiber, Nd at 1.06 μm can give an efficiency greater than 50% when pumped with a high output multiple stripe laser diode. In silica, laser emission has also been obtained from Pr, Sm, Ho, Tm and Yb. The lower energy phonon spectra of heavy metal fluorides has allowed for significant population in energy levels that are quenched in silicates, thereby giving additional laser transitions. Particularly striking in this regard are Ho and Tm which lase at shorter wave lengths than the pump by up-conversion through stepwise absorption of successive pump photons. Tm can lase at 455 and 480 nm when pumped with 640-690 nm radiation. Energy transfer between ions has been used for fluorescence sensitization, terminal state depletion and up-conversion. The configurations for laser oscillators, amplifiers, and super-luminescent sources will be discussed.
Optical fiber components
Authors: Hill K. O. , Johnson D. C. , Bilodeau F. , Malo B.
Published: February 2023

Monomode optical fiber components are required to perform many functions, including bi-/multi-furcation, filtering, polarizing and wavelength-dependent routing of optical signals, in the sophisticated optical communication network topologies that are emerging.
Integration of fiber components and amplifiers
Authors: Payne D. N.
Published: February 2023

Summary not available at time of publication.
Chirped Bragg optical fiber filter with 22-nm bandwidth
Authors: Farries M. C. , Ragdale C. M. , Reid D. C. J.
Published: February 2023

Future optical communication requires low loss fiber filters for wave length division multiplexing and rejection of unwanted pump light from fiber amplifiers. Some are currently available based on interference filters1 or rare earth doping.2 Efficient optical fiber reflection filters can be made by fabricating a Bragg grating on a polished fiber by two beam interference and then etching the grating into the fiber.3
In-fiber acousto-optic frequency shifter
Authors: Patterson D. B. , Digonnet M. J. F. , Liu A. C. , Kino G. S. , Khuri-Yakub B. T.
Published: February 2023

An all-fiber frequency shifter has been developed, based on acousto-optically induced intermodal coupling in a dual-mode fiber at 1.3 μm. We have incorporated several design variations on earlier device configurations1-3 which provide a more robust modulator with the potential for greater spurious signal suppression.
Localized surface plasmons for waveguide polarizers
Authors: Bloemer Mark
Published: February 2023

Passive polarizers are standard components in bulk and guided-wave optical systems. Guided-wave polarizers include metal/dielectric overlays,1 anisotropic crystals,2 and proton-exchanged waveguides.3 Here we report experimental results of a passive guided-wave polarizer by using surface-plasmon modes localized in small Ag particles.
Beam-propagation method for anisotropic optical waveguides
Authors: Bassi P. , Tartarini G. , Zoboli M. , Di Pasquale F.
Published: February 2023

The beam-propagation method (BPM) is a widespread tool to model isotropic optical devices. Here, an extension of the BPM to study propagation in anisotropic media with nondiagonal dielectric permittivity tensor £ is proposed. The main features of the present approach compared with others1,2 lie in the possibility to study contemporaneously the three coupled components of the electric field

E
¯

(allowing application to nonaxial propagation) and to analyze structures with different ordinary and extraordinary index variations. Starting from the vector Helmholtz wave equation (i.e., assuming

∇
⋅

E
¯

=
0

) and letting the dielectric tensor ε
r
= ε
m
0I + Δε = (n
m
0I + Δn)2 (where n
m
0 = (n
o
0 + n
e
0))/2 and Δn
ij
≪n
m
0 is assumed), tensorial phase factor, corrector and propagator terms can be separated in the expression of

E
¯

with the same formal procedure used in isotropic media.3 The field propagated over Δz in the unperturbed region is then corrected by exp(−jk0ΔnΔz), which carries out the components coupling owing to both anisotropy and non-homogeneity. The choice of a constant and appropriate value nmo, involving the assumption of an isotropic, homogeneous substrate, is necessary to fulfill matricial algebra requirements in separating tensorial propagator and corrector terms.
Impurity-induced layer disordering of quantum-well heterostructures for integrated optoelectronics
Authors: Paoli Thomas L. , Thornton Robert L
Published: February 2023

Impurity-induced layer disordering is potentially an enabling technology for economically integrating optical and electronic devices. We will review the application of layer disordering as an optoelectronic processing technology, review some basic optical and electronic devices successfully integrated with this technique, explore the advantages and limitations, and conclude with a vision of some directions in which this technology may evolve in the future.
Lateral bandgap engineering using shadow masked growth
Authors: Demeester P. , Zhu Y. , Moerman I. , Buydens L. , Lootens D. , De Vlaeminck K. , Van Daele P. , Baets R.
Published: February 2023

The fabrication of photonic integrated circuits requires the integration and optical coupling of waveguiding devices with different bandgaps. Recently, there has been much interest in obtaining this integration in a single growth step. One of the possibilities is to use quantum-well devices and locally change the thickness (or bandgap) by patterning the substrate.1 This paper describes the use of shadow-masked growth to obtain lateral bandgap engineering.2
Recent progress in high-silica planar lightwave circuits
Authors: Okamoto Katsunari
Published: February 2023

High silica glass planar circuits (Planar Lightwave Circuits: PLCs) are circuits that integrate fiber-matched silica waveguides on silicon substrate to provide an efficient means of interaction for the guided-wave optical signals. These circuits include FDM filters for extracting a specific optical signal from multiple signal channels and 8 148 8 matrix switches with thermo-optic (TO) switching elements. Silica waveguides are fabricated with a combination of Flame Hydrolysis Deposition (FHD) and Reactive Ion Etching (RIE). Since a waveguide structure is well defined, device performance can be predicted quire precisely by the numerical simulation and the desired circuits are fabricated with high precision and reproducibility.
Loss reduction of ion-exchanged glass waveguide Y-junction
Authors: Nakama Kenichi , Kobayashi Shigeru , Hashizume Hideki , Seki Masafumi
Published: February 2023

Y-junctions are important as switches,1 modulators,2 and power dividers.3 Ion-exchanged glass waveguide power dividers using Y-junctions are attractive because of their low loss, low cost, and mass productivity. One problem of such structures is radiation loss at the junction. Many theoretical and experimental studies have been done on this problem.1-3 Here we report a loss reduction method of buried single-mode Y-junctions made by a two-step thermal ion-exchange process,4 modified mask patterns in order to reduce the radiation loss, and fabrication results.
A novel waveguided polarization mode splitter using refractive index changes induced by superlattice disordering
Authors: Suzuki Yasuhiro , Iwamura Hidetoshi , Miyazawa Takeo , Mikami Osamu
Published: February 2023

One of the key devices in the monolithically integrated coherent receiver for polarization diversity systems is the semiconductor guided- wave polarization mode splitter. Several devices reported so far,1,2 however, require high accuracy in fabrication and/or tuning electrodes for adjusting the coupling length because directional couplers are used as a key element.
Optical wavefront phase tilt measurement and correction using AlGaAs integrated guided-wave components
Authors: Lau S. D. , Donnelly J. P. , Wang C. A. , Goodman R. B. , Rediker R. H.
Published: February 2023

An integrated optical system that produces a flat-phase output wavefront, independent of phase and power variations along the input wavefront, is proposed for use at GaAs laser wavelengths. A basic module of this system is shown in Fig. 1. Development of optical antennas for efficient input and output coupling is in progress.1 We report here the performance of the interferometer/phase-modulator feedback loop used to measure and correct the phase difference between adjacent outputs.
Modeling of III–V electronic and optoelectronic devices: an overview
Authors: Snowden Christopher M.
Published: February 2023

The rapid progress in fabrication techniques and subsequent performance of electronic and optoelectronic devices has stimulated the need for models that can give physical insight and accurately represent the operation of these devices. The advances in semiconductor device modeling have been equally dramatic, with the advent of new modeling techniques and improved numerical methods. The complexity and computationally intensive nature of physical models for III-V semiconductor devices has meant that equivalent circuit models dominate engineering design and characterization. Equivalent circuit model element values are generally obtained by fitting the circuit dependence to measured data This has been very successful for small-signal microwave operation. In contrast, large-signal equivalent circuit models require extensive measurements over a wide range of bias conditions, signal amplitudes, embedding impedances and frequencies to obtain a reliable element values. This has led to increased interest in using physical device models that are intrinsically capable of representing DC, transient, and large-signal (nonlinear) operation. Further, the introduction of new highly efficient modeling techniques has permitted physical models to be used for computer-aided design in a predictive role, for some microwave devices (MESFETs and HEMTs).1,2
Analysis of gain coupled DFB lasers
Authors: Buus J. , David K. , Morthier G. , Baets R.
Published: February 2023

Gain coupled distributed feedback lasers have recently received both experimental1 and theoretical2 attention. This structure offers a number of potential advantages such as: increased yield of single mode lasers (due to lifting of the degeneracy present in index coupled structures), reduced longitudinal spatial holeburning (due to a flat intensity profile), and reduced feedback sensitivity. It is the objective of this paper to present analytical results for a number of important device properties, these results are of significant interest for the design of gain coupled DFB lasers.
Two-dimensional simulation of vertical-cavity surface-emitting lasers
Authors: Matsumoto Masayuki
Published: February 2023

Recently intense research efforts have been made on the experimental realization of vertical-cavity surface-emitting lasers (VCSELs) with low threshold currents and moderate output powers.1 To design the laser resonators with good electrical and optical properties, supportive simulation studies will be of much help.2,3
8 GHz electro-optic polymer Mach-Zehnder modulator
Authors: Girton D. G. , Kwiatkowski S. L. , Lipscomb G. F. , Lytel R. S.
Published: February 2023

An electro-optic (EO) Mach-Zehnder modulator was fabricated from polymer materials and tested at frequencies up to 8 GHz. The device was fabricated on a Si wafer using conventional IC manufacturing equipment. Separate 50 87 microstrip electrodes were designed over each arm of the Mach-Zehnder device. Three polymer layers were deposited as shown in Fig. 1: a hard acrylate cladding layer, followed by an EO polymer from Akzo Research, bv,1 then another cladding layer. The waveguides were photobleached2 using an IC mask aligner, and microstrip electrodes was formed by gold plating. The active polymer layer was poled3 through the cladding at 70 V/ 109m for 1 min on top of a 120°C hot plate, and waveguide end faces were prepared by cleaving.
Light-controlled optical modulators using crystalline organic waveguides
Authors: Lam Juan F. , Tangonan Gregory L.
Published: February 2023

Summary not available at time of publication.
Bragg grating add-drop optical multiplexers tor InP-based optoelectronic integrated circuits
Authors: Ragdale C. M. , Reid D. C. J. , Robbins D. J. , Allen R. W. , Carter A. C. , Forbes N. W. , Charles P. , Reid T.
Published: February 2023

We have recently reported the design and operation1,2 of guided wave InP based Optoelectronic Integrated Circuit (OEIC's) for optical subscriber access links. OEIC technology has the potential for achieving the functionality required in such optical terminals at low cost, as all components, and their optical interconnections, are fabricated monolithically. Our current subscriber access chip incorporates a wavelength duplexer, to coarsely separate the 1300nm and 1550nm spectral windows. As the optical access network matures extra capacity will be required for bidirectional or distributive optical circuits. Such circuits are likely to be separated by WDM or dense WDM techniques. In this paper we present results on the design and fabrication of Bragg grating optical 'add-drop' multiplexers compatible with our demonstrated OEIC subscriber access circuits. Optical filter/multiplexer bandwidths in the range > 5nm to <0.1 nm are likely to be required to separate coarse WDM through dense WDM channels.
Autocorrelation using quasi-phase-matching waveguides
Authors: Webjörn Jonas , Galvanauskas Almantas
Published: February 2023

Autocorrelation of optical pulses by generation of second harmonic (SH) is a well established technique for picosecond and subpicosecond pulse duration measurement.1 Until now only bulk crystals have been used and the phase-matching has been achieved by birefringence. The disadvantages are that the materials for such autocorrelators must be chosen with high enough birefrigence rather than with the highest non-linearity. This leads to that low SH conversion efficiency is a problem when measuring autocorrelation traces of semiconductor laser pulses with rather low peak power.
Numerical modeling of deeply etched semiconductor rib waveguides with large mode size: comparison with experimental results
Authors: Chung Youngchul , Dagli Nadir
Published: February 2023

Semiconductor rib waveguides with large mode sizes are highly desirable for compatibility with single mode optical fibers. Although the favorable modeling tool is the beam propagation method (BPM) of various forms,1–3 BPM is not always efficient due to large computational window size needed for accurate modeling of such structures. In this paper, an explicit-finite-difference-BPM3 employing a non-uniform-mesh is used to study such structures and numerical calculations are verified by experimental results.
Numerical study of the quasi-transverse-electric mode in optical waveguide with saturable nonlinear rectangular core
Authors: Fernandez F. A. , Ettinger R. D. , Davies J. B. , Rahman B. M. A.
Published: February 2023

In the very topical problem of nonlinear waveguide analysis, progress has been reported using the finite element method,1–3 mainly in ID. Two-transverse-dimensional nonlinear modal analysis using finite elements4 or alternative methods5 requires greater sophistication, and we have shown6 that adaptive techniques are essential. This paper reports an accurate study of an important canonical problem, namely a rectangular dielectric waveguide with nonlinear core. Using fully vectorial analysis, we consider here the fundamental mode. We shall show the effect of a non-Kerr type constitutive relationship, where various amounts of saturation are introduced. The variation of spotsize and of effective index as a function of total power is plotted from small to extremely high powers to show interesting global features for the first time.
Numerical modeling of two parallel waveguides decoupled by antiresonance of the intermediate region
Authors: Bassi P. , Di Pasquale F. , Zoboli M. , Capobianco A. , De Angelis C. , Galtarossa A. , Someda C. G.
Published: February 2023

The question whether two parallel waveguides, separated by a finite spacing, can be decoupled by a suitable distribution of the refractive index, as a function of the transverse coordinates, in the intermediate region,1 has been solved analytically2 as follows. Such a requirement can never be satisfied by scalar waves, but can be satisfied if the vector nature of e.m. waves is properly accounted for.
Bending characteristics of ARROW
Authors: Chu S. T. , Huang W. P. , Chaudhuri S. K.
Published: February 2023

Since the introduction of the antiresonant reflecting optical waveguides (ARROW),1 extensive research has been devoted to the investigation of this novel way of guiding optical power.2,3 Aside from the ease of fabrication and low loss, the ARROWS provide strong confinement of optical power in the core region, so that one can stack the ARROW together to form waveguide arrays.2 The core dimension and refractive index of the ARROW can also be made similar to that of the optical fiber to obtain very good coupling efficiency at the fiber and integrated optical component interface. Low loss propagation only occurs when the interference layer is at its optimum thickness for antiresonance, consequently, the propagating characteristics in the ARROW are very sensitive to changes in polarization and wavelength and they can be readily implemented in a number of integrated components, such as sensors and polarization splitters. Because the propagation characteristic in the ARROW depends so strongly on the layer thickness of the interference layer, slight deviations in its dimensions or properties from the optimum design, for example, waveguide bends, may drastically affect the propagation characteristics in the waveguides. This behavior can be exploited and used in sensors. The purpose of the paper is to analyze the propagation characteristics at the ARROW bends.
Monolithic 0.85-μm mode-locked semiconductor laser arrays
Authors: Derickson D. J. , Morton P. A. , Jia G. , Geels R. S. , Bowers J. E. , Thornton R. L.
Published: February 2023

Mode-locked semiconductor lasers have produced ultra-short pulses in external cavity configurations by both active and passive methods. Recently, progress has been made1–3 in combining all of the required components into a single monolithic mode-locked device. These devices operated at repetition rates above 15 GHz at 1.3 μm and 1.55 μm wavelengths. Formany applications such as electrooptic sampling, A/D converters, and OTDRs, lower repetition rates are usually necessary. The devices studied in this work have a repetition rate of 5.5 GHz at a lasting wavelength of 0.85 μm.