bluuebunny/crossref_metadata_2025 huggingface dataset:
Dynamics of Atomic Excitations by Chirped Pulses
Authors: Carroll C.E. , Hioe F.T.
Published: February 2023

We have found new analytic results for a wide variety of atomic excitation processes which involve the use of amplitude-and frequency-modulated laser pulses: (1) We have unified all the previously known solutions including those of Rosen and Zener,1 Landau2 and Zener,3 Rabi,4 Bambini and Berman,5 Demkov,6 McCall and Hahn,7 Allen and Eberly,8 and Hioe,9 among others, and have significantly extended it with expressions involving three free parameters and an arbitrary function to an infinite variety of amplitude-and frequency-modulated laser pulses.10 We have found a simple condition which the three essential parameters in the amplitude-and frequency-modulation functions must satisfy in order to achieve a complete population inversion, or to achieve a complete population restoration as in the case of self-induced transparency7 or soliton propagation.
A Study of the Macroscopic Quantum Fluctuations of Stimulated Raman Scattering from a Partially Coherent Source
Authors: Raymer Michael G. , Walmsley Ian A.
Published: February 2023

A pencil shaped region of a Raman-active medium forms a source for Stokes-shifted light via stimulated Raman Scattering (SRS) when driven by an intense laser pulse. Stokes photons are scattered spontaneously at first, and then amplified during propagation through the medium. Since the scattering is initiated by quantum noise, the actual number of photons produced in any given pulse will be highly uncertain, even if the pulse energy of the driving laser is constant1. As the Stokes light propagates through such an extended region, it's coherence properties will be changed. The spatial coherence is determined by the size and shape of the region, which may be characterized by its Fresnel number F, defined as F= A/λSL, where A is the cross-sectional area of the interaction region, which has length L, and λS is the Stokes wavelength. The rate at which the microscopic scatterers (atoms or molecules) are dephased by collisions affects the temporal coherence of the Stokes light, characterised by the temporal coherence parameter Γτ /gL, where Γ is the collisional dephasing rate, τ is the laser pulse duration and g is the steady-state Raman gain coefficient.
Degenerate four-wave mixing of picosecond light pulses in soluble polydiacetylenes
Authors: Dennis W.M. , Blau W. , Bradley D.J. , Schulz R.C. , Rau N.O. , Plachetta C.
Published: February 2023

Optical phase conjugation by degenerate four-wave mixing of picosecond light pulses in polydiacetylene solutions has been observed with reflectivities up to 600%. The coupling mechanisms are ultrafast Kerr-like nonlinear susceptibility and thermally induced refractive index changes.
Large Signal Analysis of Phase Variations and Bistability in Degenerate Four-Wave Mixing
Authors: Tajima Kazuhito , Hsu Hsiung
Published: February 2023

Large signal analyses for degenerate four-wave mixing (DFWM) have been reported for sometime(1-3). It was nevertheless not obvious why, in specific examples(1,2). DFWM exhibits hysteresis and bistability characteristics, whereas in the case of ideal phase conjugation(3), there is no such instability. The objective of this paper is to show that hysteresis and bistability are caused by phase variations in the interaction. These phase variations are detrimental to phase conjugation and may Indeed up-set the basic characteristies of phase conjugation.
Observation of Phase-Sensitive Noise in Sodium Vapor
Authors: Maeda Mari W. , Kumar Prem , Shapiro Jeffrey H.
Published: February 2023

Squeezed states of light exhibit phase-sensitive quantum noise, which can be measured via optical homodyne detection. Squeezed state generation has been predicted in degenerate four-wave mixing, resonance fluorescence, and nonlinear propagation. We report observing phase-sensitive noise via optical homodyning on a cw dye laser beam which has propagated through sodium vapor near the D-lines.
Intermodal Bistability and Bimodality in Coupled-Cavity Semiconductor Lasers
Authors: Lang Robert J. , Yariv Amnon
Published: February 2023

Coupled-cavity semiconductor lasers are known to exhibit bistability under certain circumstances. There are two distinctly different manifestations of bistability; in the first, the laser is capable of exciting the same longitudinal mode at different power and carrier densities (intramodal bistability); in the second, the laser switches between two different longitudinal modes (intermodal bistability). The latter case is the subject of this paper.
Observation of Instabilities and chaos in a single longitudinal, multitransverse mode cw-CO2 laser
Authors: Biswas Dhruba J. , Harrison Robert G.
Published: February 2023

Here we report on the observation of oscillatory instability leading to chaos in, a single longitudinal but multitransverse mode cw-CO2 laser. Particularly significant we find en route to chaos distinct and stable oscillation involving three transverse modes.
Transverse Effects Self-Action Instabilities in the Simultaneous Propagation of Short Different-Wavelength Pulses in Three-Level Absorbers†
Authors: Mattarff F.P. , Harrison George R. , Babuel-Peyrissac J.P. , Marinier J.P. , Bardin C.
Published: February 2023

This paper is devoted to understanding the temporal synchronization of the two-color superfluorescence output powers. Following McCall and Feld et al., the monochromatic superfluorescence can be described in terms of a semi-classical propagational model that shares the same equations as Self-Induced Transparency (SIT). Thus it became important to understand double SIT that was discovered by McCall and Hahn (MH) to correctly interpret co-propagating beams with coherent exchange of energy and nonlinear phase evolution. A further motivation would be to elucidate pump and Stokes synchronization as well as pump depletion effect on Stokes buildup in Raman forward amplifier. In this work, we describe how the diffraction affects the longitudinal and transverse reshaping associated affects the simultaneous resonant propagation of two different-wavelength optical pulses in a three-level medium. The pulse lengths are shorter than any of the relaxation times, thus, the interaction is coherent. The material response has an inertial characteristic, which precludes its description with two instantaneous susceptibilities, and requires instead the density matrix formulism. A semi-classical formulism, as introduced by Konopnicki and Eberly (KE), is adopted in which two paraxial Maxwell field equations are closely intertwined in the generalized three-level Bloch equations.
Effects Of Stark Shifts On Two-Photon Sidemode Instabilities
Authors: Ovadia Snlomo , Sargent Murray
Published: February 2023

In a recent paper,1 we considered the stability of single-mode operation in two-photon lasers and two-photon optical bistability.2 The models assumed that two photons of equal or nearly equal frequencies span the atomic two-photon transition, with no resonant intermediate levels. The paper neglects possible Stark shifts of the two levels due to virtual transitions to nonresonant levels and back. For one-photon processes, these virtual transitions can be neglected because they have one nonresonant denominator. They cannot in general be neglected for the two-photon case, however, since all transition probabilities have at least one nonresonant denominator. In this paper we give formulas and illustrations for the two-photon two-level absorption and coupling coefficients including Stark shifts. For vanishing shifts, the coefficients have symmetric spectra that look very similar to their one-photon counterparts, but for nonzero shifts, they have asymmetric spectra with exaggerated resonances. These resonances appear to increase the likelihood of instabilities for certain combinations of pump detuning and Stark shifts.
Stability of Single-Mode Optically-Pumped Lasers
Authors: Dupertuis M.A. , Salomaa R.R.E. , Siegrist M.R.
Published: February 2023

We analyse the probe gain of coherently pumped lasers and perform stability analyses. The usefulness of the dressed atom picture will be illustrated and an application to FIR lasers presented.
Fresnel Lens in Thin Film Waveguides
Authors: Ashley P. R. , Chang W. S. C.
Published: February 2023

Signal processing in thin film waveguides requires the use of diffraction limited aberration-free lenses. A major factor limiting the performance of all the thin film waveguide lenses is the small Δn that can be obtained using existing materials. Currently, only the Geodesic and the Luneberg lenses have been investigated1-4. They are basically thick lenses. At low F-numbers, they have exhibited large aberrations. Corrections for these aberrations are hindered by the difficulties in the fabrication processes for obtaining non-spherical contours.
Channel Waveguide Array Coupled to an Integrated Charge-Coupled Device (CCD)*
Authors: Chen C.L. , Boyd J.T.
Published: February 2023

An optical channel waveguide array coupled to a charge-coupled device (CCD) linear imaging array and integrated onto the same silicon substrate has been fabricated and successfully operated. The channel waveguide array is formed by preferential-etching of V-grooves in the 100 plane of silicon.1 The integrated device differs from slab waveguide-CCD structures2,3 in that the present structure is configured such that an individual channel waveguide is coupled to each array element of the CCD image sensor. The channel waveguide structure thus provides a method for parallel injection of signals into a CCD which eliminates crosstalk due to capacitive coupling associated with high frequency electrical signal injection and which provides greater channel isolation and channel density than a comparable bulk optical wave structure.4
Programable Optical IC Using Bi12SiO20 Crystal
Authors: Hayashi Hideki , Fujii Yoichi
Published: February 2023

In this paper, a new optical IC device, which an arbitrary refractive index distribution pattern can be written in and erased optically, is proposed and some characteristics of this device are experimentally verified. This device utilizes the combination of three physical properties of Bi12SiO20(BSO) crystal: a large electro-optic effect, a strongly wavelength-dependent photoconductivity effect, and a high dark resistivity with long carrier trapping time. These properties of BSO are used in PROM (Pockels Readout Optical Modulator) type memory and display device.(1)(2)
Single Mode Fiber at Zero-dispersion Wavelength
Authors: NiiZeki Nobukazu
Published: February 2023

A single mode fiber with very low loss of 0.5 dB/km at 1.30 μm has been attained. Very low dispersion was experimentally confirmed at 1.29 μm in a 10.4 km fiber system.
Integrated Optics for Wavelength Division Multiplexing
Authors: Nakamura M.
Published: February 2023

Optical wavelength division multiplexing is a method by which optical signals of various wavelengths are multiplexed and transmitted in a single fiber. This should prove useful in high speed digital transmission because of the large transmission capacity achievable without increasing the bit rate. It will also be effective in applications to video services in subscriber loops.1) The feasibility of wavelength division multiplexing transmission has recently been demonstrated by Ishio et al.2) and Sugimoto et al.3). Three optical signals have been multiplexed and demultiplexed using descrete lenses and a CdS prism.
A High Performance Avalanche Photodiode at 1.0-1.7 μm, Compatible with InP/GaxIn1−xAsyP1−y Integrated Optics Technology
Authors: Pearsall T. P. , Dipda E. , Papuchon M. , Roullet G.
Published: February 2023

The GaxIn1−xAsyP1−y lattice-matched quaternary alloy system is particularly promising both for the development of integrated optical circuits realized on InP substrates, and the utilization of these circuits in fiber optic communication systems in the 1.30-1.35/um low-loss, zero dispersion spectral window. The complete optical communication system is composed of an emitter, transmission medium and receiver. Although considerable attention has been paid to the development of new luminescent sources1 and optical waveguides2 near the 1.3/um regime of the optical spectrum, there has been no equivalent development of a detector suitable for optical signal processing in this spectral region. In this paper we present the Ga0.47In0.53As homojunction avalanche photodiode, the first photodiode fully integrable with sources and waveguides on InP substrates. With a direct bandgap at 1.7 um, this photodiode is sensitive to radiation from nearly any proposed GaxIn1−xAsyP1−y luminescent device which can be grown lattice-matched on InP. Operating at room-temperature, these photo-detectors have a dark-current level three orders of magnitude less than that of germanium photodiodes (which show a similar spectral response, but which cannot in any case be grown on InP).
Monolithic Integration of LOC-DBR Lasers and Optical Components
Authors: Shams M. K. , Namizaki H. , Wang S.
Published: February 2023

Monolithically integrated GaAs-(GaAl)As optical circuits have been reported by Merz et al.[1] who integrated an etched-reflector laser and a detector, and Aiki et al.[2] who made a frequency multiplexer by single-chip integration of several DFB lasers. Reinhart et al. have also demonstrated a sophisticated LPE process which is capable of fabricating complex integrated optical circuits [3].
Twin-Guide Laser Monolithically Integrated with Amplifier or Detector
Authors: Kishino K. , Suematsu Y. , Utaka K. , Kawanishi H.
Published: February 2023

An integrated twin-guide(ITG for short) laser consists of an active waveguide-layer for the laser oscillation, the light amplification and the detection etc., and an external passive waveguide through which the laser light is coupled amoung elements to each other [1]–[4]. Thus it is possible to integrate monolithically many optical elements by such structure.
A Movie on the Visualization by Fluorescence of the Electrically Controlled Optical Directional Coupler
Authors: Papuchon M. , Puech B. , Puech C. , Ostrowsky D.B.
Published: February 2023

High performances electrooptically controlled optical directional couplers have already been realized in several laboratories using electrooptical crystals like LiTaO3 or LiNbO3 and Niobium or Titanium in diffusion to create the waveguides (1, 2, 3, 4). In parallel we have developped in our laboratory a technique called "visualization by fluorescence" to display the guided energy in optical waveguides with low as well as high refractive indices.
Optically-Controlled Two Channel Integrated-Optical Switch
Authors: Cross P. S. , Schmidt R. V. , Thornton R. L.
Published: February 2023

An integrated optically-controlled, four-port bistable switch based on a waveguide directional coupler is demonstrated. The two usable output ports allow functions such as remote optical switching to be performed.
Electrooptic Scanning of Light Coupled from a Corrugated LiNbO3 Waveguide
Authors: Hong C. S. , Yariv A.
Published: February 2023

Periodic perturbations of dielectric waveguides have been used extensively for reflection [1], output coupling [2], and Bragg deflection [3,4]. In the latter case Bragg diffraction of light from a variable wavelength acoustic wave was used for scanning the optical beam [4].
Loss Measurements in Diffused LiNbO3 Waveguides
Authors: Kaminow I. P. , Stulz L. W.
Published: February 2023

The insertion loss, L = −10 log T, is an important characteristic of any optical waveguide device; it is especially important for resonator devices.1 The small losses in diffused LiNbO3 strip guides have been difficult to measure because of the poor reproducibility of input/output coupling with prisms or polished end-faces. Cleaving the end-faces of properly oriented and sufficiently thin LiNbO3 substrates is a quick and convenient means for preparing reproducible surfaces.2
A Novel Leaky-Wave Strip Waveguide Directional Coupler
Authors: Hu E-W. , Peng S.T. , Oliner A. A.
Published: February 2023

A new type of directional coupler for integrated optics is presented here which looks like the ordinary strip waveguide type of directional coupler but which operates on a different coupling mechanism. As shown in Fig. 1, the coupler consists of two strip waveguides placed on a thin film on a substrate, where the two strips couple to each other over a given length. However, its operation allows a greater separation between the two strips than is present in the customary coupler.
Length Optimization of an S-Shaped Transition Between Offset Optical Waveguides
Authors: Marcuse D.
Published: February 2023

It is often desirable to connect two waveguides of an integrated optical circuit. An obvious solution to this connection problem is shown in Fig. 1a where two waveguides are joined by a slanted straight transition. Aside from the disadvantage of the two sharp tilts in the resulting waveguide, there may be an additional problem with this structure arising from the fact that waveguides for integrated optics are often fabricated with the help of an electron microscope. The electron microscope is used to make the mask that, in turn, is needed for the photolitographic process used to produce the actual waveguide circuit. Some electron microscopes operating under computer control are only able to write vertical or horizontal lines, slanted lines must be approximated by staircase curves. The waveguide of Fig. 1a would thus assume the shape shown in Fig. 1b. In the following discussion we shall always assume that only staircase curves can be produced.
Holograms Recorded and Read-out with the Evanescent Field of Guided Waves
Authors: Lukosz W. , Wüthrich A.
Published: February 2023

We report the experimental realization of holograms recorded and read-out with the evanescent field of a mode propagating in a planar waveguide as reference wave. We also present a theory of the diffraction efficiencies of this new type of holograms, which we have proposed earlier [1].
Optical Propagation in Bragg Fibers*
Authors: Yeh Pochi , Yariv Amnon , Marom Emanuel
Published: February 2023

Confind lossless propagation of optical waves in cylindrical Bragg fibers with a low refractive index core is proposed and analyzed. Prospective applications are presented.
Narrow-Channel Double-Current-Confinement CSP Laser and Effect of the Current Distribution on its Performance
Authors: Chen Chung-Yih , Wang Shyh
Published: February 2023

Among the various lasers being developed, the CSP laser [1] and the BH laser [2] (or the improved version SBH laser [3]) are considered to possess outstanding features for use as coherent sources. In the case of CSP laser, the lasing mode is stabilized by modal discrimination between fundamental and higher order modes provided by the coupling loss in the shoulder region. As a result, the active and cladding layer thicknesses (referred to as d and t, respectively) are crucial parameters to the performance of the CSP laser. In fact, the value of d should be less than 0.1μm and t should be within 0.3 to 0.4μm, as pointed out in Ref. [1]. Meanwhile, the semiconductor laser with stripe width less than carrier diffusion length has not been extensively studied although narrow stripe lasers have been shown to increase mode stability and to exhibit two-lobed far field pattern.
Room-Temperature Operation of GaInAsP/InP Integrated Twin-Guide Lasers with First-Order Distributed Bragg Reflector
Authors: Utaka K. , Suematsu Y. , Kobayashi K. , Kawanishi H.
Published: February 2023

Stable-single-longitudinal-mode lasers in the wavelength region of 1.0~1.7μm, such as distributed Bragg reflector (DBR) lasers1),2) and distributed-feedback (DFB) lasers 3), are very interesting for the low-loss optical communications4) and the integrated optics in that wavelength region. In order to realize an effective DBR laser, it is essential to introduce a low-loss waveguide on which distributed Bragg reflectors are fabricated with first-order gratings. An integrated twin-guide structure5) is one candidate for this purpose6), since gratings can be fabricated on its low-loss output guide.
GaAs-(GaAl)As Double-Heterojunction Injection Laser with a Pillbox Resonator
Authors: Liao Andrew Shuh-Huei , Wang Shyh
Published: February 2023

Pillbox resonator(1) is among one of the earliest circuit components suggested for integrated optics and considered especially useful in wavelength multiplexing. However, before such integrated optical circuits can be realized, certain features associated with a curved waveguiding structure must be understood and thus they can be either overcome or utilized. One obvious problem is the excess loss caused by radiation and scattering in a curved guide. This problem has been studied(1-3) both theoretically and experimentally, and is well understood. An equally important but more complex problem is the coupling between a curved and straight guide. This latter problem has not been extensively stuided.
High-Output Power InGaAsP Strip-Buried-Heterostructure Lasers
Authors: Wright P. D. , Nelson R. J. , Barnes P. A.
Published: February 2023

Strip-buried-heterostructure (SBH) lasers fabricated from GaAlAs for use at 0.88 μm have been shown to possess many desirable properties.1,2 In the present work we describe the first demonstration of an InGaAsP SBH laser for use at 1.3 μm. The long wavelength SBH laser retains the desirable properties of the GaAlAs device including stable-fundamental-mode operation, linear light-current characteristic, high output power and a narrower beam divergence than for simple buried heterostructure (BH) lasers.3 In addition to these excellent properties the InGaAsP SBH laser is shown to be capable of a maximum power output at least twice as high as comparable GaAlAs SBH lasers1 without the occurrence of catastrophic mirror damage.
High Quantum Efficiency Waveguide Coupled Photodetectors on Silicon Substrate
Authors: Yao S. K. , August R. R.
Published: February 2023

The advantage of building integrated optical devices on silicon substrate is to utilize the superb electronics properties of silicon. Of particular importance is the possibility of constructing various types of photodetectors which are directly coupled to the optical circuitry monolithically, because photodetectors are required in nearly every integrated optics applications. Waveguide coupled photodetectors on silicon substrate have been reported before both as photodiode array1 and as CCD array.2 In this paper, we report the experimental result of a high quantum efficiency waveguide coupled photodetector using controlled chemical etch profile for reproduceable efficient waveguide/detector coupling. In addition, the optical waveguide used is the widely accepted 7059 glass/SiO2/Si structure rather than the KPR photoresist1,2. Furthermore, we have shown that the waveguide/detector transition structure employed is compatible to the construction of a very high density (4 micron periode) detector array, which is often needed for certain applications such as the integrated optical spectrum analyzer.3,4
AℓxGa1-xAs/AℓyGa1-yAs Heterostructure Lasers Grown by Molecular Beam Epitaxy
Authors: Tsang W. T.
Published: February 2023

Molecular beam epitaxy (MBE)1 is a crystal growth technique that is most suitable for the preparation and integration of opto-electronỉc devices. It not only permits the growth of very high quality large area (can be as large as 4 in2) uniform and smooth layers with precisely controlled thicknesses and chemical compositions, it also allows selective area growth of patterned multilayer structures with specific material compositions,2,3 and writing of epitaxial line structures with lengthwise varying thickness, chemical composition, and controlled thickness profiles.4 With MBE, very low current-threshold AℓxGa1-xAs/AℓyGa1-y As double-heterostructure (DH) lasers have also been prepared covering the active layer thickness from ~ 300 Å to 4000 Å5,6 and the lasing emission wavelength from 8900 Å to 7200 Å.
Influence of Growth Conditions on The Threshold Current Density of Double Heterostructure Lasers Prepared by Molecular Beam Epitaxy
Authors: Cho A. Y. , Casey H. C. , Radice C. , Foy P. W.
Published: February 2023

The effect on threshold current density Jth of the use of an air-lock sample exchange mechanism, substrate preparation, and Al source purity was investigated for GaAs-Al0.27Ga0.73As double heterostructure (DH) lasers grown by molecular-beam epitaxy (MBE). The importance of having an airlock sample exchange can be illustrated by the improvement of threshold current density as a function of the number of runs after the growth chamber is opened to atmosphere for oven refilling. Usually the threshold current density Jth is more than four times higher than that of wafers grown by liquid phase epitaxy on the first run, and then Jth improves to about 1.5 times higher on the third and fourth runs. Finally, Jth on the fifth and later runs is comparable to that for wafers grown by LPE. Also, care must be taken in substrate selection and preparation and in the use of Al free of undesirable impurities. The detailed sample preparation and the analysis of the Al source will be discussed. Figure 1 shows the temperature-time cycles used to grow the DH lasers. Broad-area lasers with cavity lengths between 400 to 500 μm having Jth of 1.25×103, 1.16x103, 1.04×103 A/cm2 for active layer thickness of 0.22, 0.16 and 0.10 μm respectively have been achieved. For a cavity length of 570 μm, the wafer with 0.1 μm active layer gave Jth as low as 910 A/cm2. These DH lasers have been fabricated as proton bombarded stripe-geometry lasers (12 μm × 380 μm) and have a room temperature threshold current of 80 mA. The desirable features of molecular beam epitaxy are the capability of growth over a large substrate area (4 cm x 2.5 cm) and the reproducibility of this growth technique.
Analysis and Design of Blazed Dielectric Gratings
Authors: Tamir T. , Chang K.C.
Published: February 2023

Dielectric gratings that convert surface waves into beams (or vice-versa) can couple energy from the optical waveguide equally well into both the regions above and below the grating. However, because a single beam is usually needed, this results in a coupling efficiency loss of about 50%. Such a loss can be substantially reduced by "blazing” the grating, i.e., choosing a suitable asymmetric profile that couples energy mostly into only one of the two regions. Although considerations are available(1-4) for constructing specific dielectric gratings with good blazing properties, the general problem of designing highly efficient gratings has not been fully resolved.
Recent Developments in Guided Waves Optical Roatation Sensors
Authors: Arditty Herve
Published: February 2023

Passive optical rotation sensors making use of guided-waves-optics are being investigated as potentially low-cost, high-sensitivity alternatives to laser-gyroscopes. After a review of recent work in this area, an experiment demonstrating quasi-photon-noise-limited sensitivity and stability of a fiber-optics sagnac interferometer is reported. Integration of the sensor on LiNbO3 is described.
Linear Interferometric Modulator for Electromagnetic Field Detection
Authors: Bulmer C. H. , Burns W. K. , Moeller R. P.
Published: February 2023

An electro-optic modulator is well suited for the detection of electromagnetic radiation. Bassen and Peterson1 used a bulk electro-optic crystal modulator to detect radiation collected at a dipole antenna, which is connected to electrodes on the crystal faces. Burns et al.2 have developed a polarization-independent interferometric channel waveguide modulator, in which the output decreased quadratically with voltage. Replacement of the bulk crystal with an integrated optical modulator of this type should produce a smaller detector, with a shorter dipole, operable over a wide dynamic range and having optical input and output through single-mode fibers.
Optical Scattering Phenomena in LiNbO3 Waveguides
Authors: Vahey David W.
Published: February 2023

The attractiveness of performing acoustooptic spectrum analysis using integrated optical circuitry is well documented in the literature(1,2), and considerable research has been performed to perfect and integrate the various components of such circuitry.(3,4,5,6) Our concern is with the waveguide, and in particular with the reduction of system noise associated with waveguide scattering. Special attention has been given to waveguides formed in LiNbO3 substrates by Ti diffusion and to "in-plane" scattering events in which both incident and scattered photons are confined to discrete modes, but propagate in different directions in the plane of the waveguide. This type of scattering is associated with the detection of spurious optical signals which can limit the dynamic range of a spectrum analyzer.(7,8)
Electrooptical Channel Waveguide Matrix Switch Using Total Internal Reflection*
Authors: El-Akkari F.R. , Chang C.L. , Tsai C.S.
Published: February 2023

High-speed low-drive power guided-wave optical matrix switches should perform various functions in future wideband multichannel integrated and fiber optic systems. An integrated optical switching matrix (network) was first described by Taylor(1) and a 4x4 switching network was later realized in a LiNbO3 substrate using five stepped Δβ reversal directional-coupler switches(2) by Schmidt.(3) In this paper we will report on an electrooptical channel waveguide matrix switch which utilizes total internal reflection (TIR) in a Y-cut LiNbO3 substrate. We will first present the performance characteristics of a basic channel waveguide TIR switch which is an improved version of the one we reported earlier.(4) We will then describe the design, fabrication, measurement technique, and the performance characteristics of a 3x3 and a 4x4 integrated switching matrices consisting of such basic TIR switches.
Development and Applications of High-Speed InP Optoelectronic Switches*
Authors: Leonberger F. J. , Moulton P. F.
Published: February 2023

High-speed InP optoelectronic switches have been developed for analog signal processing applications. Switches of this type were originally demonstrated in Si (Ref. 1,2) and GaAs (Ref. 3) and have been used for a number of signal generation and processing applications.4 These previously reported devices had a relatively high on-state impedance and/or their laser drivers had a low duty cycle. The InP switches reported here overcome these problems and hence they are better suited for some important analog processing functions than either the Si or GaAs switches. The InP switches have typically a 30-psec rise time and have been used to generate a train of 70-psec-wide pulses at 900 MHz and to accurately sample an rf signal at 275 and 550 MS/s.
Characteristics of (GaAℓ)As Injection Lasers Operating with an Optical Fiber External Resonator
Authors: Figueroa L. , Lau K. , Yen H.W. , Yariv A.
Published: February 2023

The operation of injection lasers with an external optical cavity has become an important subject because it can lead to the generation of short optical pulses at Ghz rates. Potential applications for such pulses are optic logic circuits and the phase locking of microwave semiconductor sources. Conventional external cavities, composed of lenses and mirrors, are bulky and difficult to align. In this talk we report the characteristics of a novel external cavity configuration which is mechanically stable and simple to construct. The external cavity consists of a piece of multimode graded index fiber with both ends cleaved. One end of the fiber is coated with a thin layer of Au to form a reflector. A spherical lens (typically 80-100 µ in radius) is formed on the other end of the fiber. By aligning the lase(1) to the lens end of the fiber we have obtained laser oscillation in the composite cavity whose threshold was typically 6-10% less than without the fiber resonator. The light output vs. current is shown in Figure 1.
A Linear Total Internal Reflection Spatial Light Modulator and its Application in Optical Information Processing
Authors: Flores L. N. , Hecht D. L. , Johnson R. V. , Nafarrate A. , Sprague R. A. , Turner W. D.
Published: February 2023

A TIR (Total Internal Reflection) linear spatial light modulator having over five thousand resolvable elements was recently developed for laser printing applications.1,2,3 This device has similarity to many of the integrated optics concepts currently being pursued in that a fringing electric field in an electro-optic crystal is used to modulate light in the vicinity of the crystal surface. This paper describes the operation of this device and shows how it can be used in coherent optical processing.
High Power Butt Coupling of Diode Lasers to LiNbO3 Waveguides With Coupling Efficiencies Greater Than 65%*
Authors: Hammer J. M. , Botez D.
Published: February 2023

Butt coupling efficiencies as high as 78% and averaging over 65% have been observed in coupling light from constricted double heterostructure large optical cavity lasers (CDH-LOC)(1) to both Ti-LiNbO3(2) and Nb-LiTaO3(3) optical waveguides. Power levels in the waveguide of 13 mW (cw) and 27 mW (5 μs 5% duty cycle pulses) have also been observed. These are the highest reported efficiencies and powers coupled by any means from diode lasers to LiNbO3 waveguides. The observations support the theory relating beam waist size to coupling efficiency(4) at very high waveguide powers and coupling efficiencies.
High Efficiency Single-Mode Fiber to Ti:LiNbO3 Waveguide Coupling at λ=1.32μm
Authors: Alferness R. C. , Ramaswamy V. , Divino M. D. , Buhl L. L.
Published: February 2023

As a result of the significant progress in Ti:LiNbO3 waveguide device research in the last several years, these devices now show great promise for use in high data rate lightwave systems as well as for signal processing applications. Guided-wave modulators, switches and filters with impressive figures of merit have now been demonstrated in several laboratories. However, the practicality of these devices for systems applications is frequently questioned because devices reported to date have relatively high insertion loss and low fiber-waveguide coupling efficiency. Clearly, for the full potential of these devices to be realized, low waveguide loss and efficient fiber-waveguide coupling are essential. Currently, the lowest reported fiber-waveguide-fiber insertion loss for a 1 cm long straight Ti:LiNbO3 waveguide is 2.5-3.0 dB for λ=1.15μm and λ=.6328μm2, respectively.3 Much poorer results have been previously achieved for waveguide circuits, e.g., directional couplers, required for devices. By carefully selecting diffusion conditions to enhance the match between fiber and waveguide modes, we have achieved fiber-waveguide-fiber insertion loss as low as 1 dB for a 1.3 cm long straight Ti:LiNbO3 waveguide and 1.65 dB for a 2 cm long directional coupler for λ=1.32μm.
Chemically Etched Conical Microlenses for Coupling Single Mode Lasers into Single Mode Fibers
Authors: Eisenstein G. , Vitello D.
Published: February 2023

Coupling efficiency between single mode laser diodes and single mode fibers can be greatly increased by using lensing schemes to match their respective modes. Various such schemes have been reported [1-8]. Among these, microlenses formed out of the fiber itself are solid and have stable optical properties. The best results demonstrated have been achieved using complicated techniques to control the lens radius of curvature and to ensure that the lens is aligned with the fiber core.
Optical Second Harmonic Generation in Crystal Cored Fibers
Authors: Nayar B K
Published: February 2023

Optical Second Harmonic Generation (SHG) has been reported in planar waveguides, using waveguide dispersion to phase match the fundamental and Second Harmonic (SH) modes1-6. The optimum waveguide dispersion is generally achieved by the correct choice of waveguide dimensions. In practice however the inability to maintain uniform guide dimensions has limited the useful interaction length for SHG to less than 2 cms.
Doubly Degenerate Four-Wave Mixing in Optical Waveguides
Authors: Lattes A. , Gabriel C. , Haus H. A.
Published: February 2023

A TM wave excited in a Ti indiffused waveguide in LiNbO3 was observed to change into TE at the waveguide output within times of the order of tens of seconds after "turn-on". The waveguides were fabricated in x cut y propagating LiNbO3 and were single mode at the frequency of interest. The observations were made with λ = 6328 Å radiation at power levels of the order of 40 μw. The rate at which the changes take place is a function of the input power and it is not observed at very low power levels. An initial TE-excitation does not change into TM. In the simplest context, the phenomenon is tied to the well known "optical damage" in LiNbO3. The explanation of the effect is complicated by the fact that the TE and TM waves are greatly phase-mismatched and no efficient coupling ought to occur between them.
External Cavity Controlled Operation of a Semiconductor Diode Gain Element in Series with an Optical Fiber*
Authors: Rediker R. H. , Schloss R. P. , Mooradian A. , Welford D.
Published: February 2023

The series combination of a semiconductor-diode gain element (a diode laser whose end facets have been antireflection coated) and an optical fiber has been placed inside an external cavity as illustrated in Fig. 1. The external cavity operated with an output at a single wavelength whose width was less than the 1.7 × 10–5-nm resolution of the scanning Fabry-Perot interferometer used. The spectrum illustrated in Fig. 2 is for a multimode optical fiber inside the cavity. When a grating in the Littrow configuration is used as one of the cavity end reflectors, the spectral line can be tuned. Other elements such as a polarizer can also be placed inside the cavity at the fiber output to select the polarization of this output. With proper alignment of the elements inside the cavity, temporally stable operation of the external cavity output is obtained— there are no spikes or fluctuations within the 225 MHz bandwidth of the detection circuit, there is negligible modal noise as measured on a sprectrum analyzer, and the drift in output which occurs over the order of several minutes is consistent with thermal variations expected in the experiment.
Relation of Carrier-Induced Index Change to the Development of Feedback Noise in Diode Lasers
Authors: Fye D. M.
Published: February 2023

Recent experimental studies of feedback-induced noise in single-mode diode lasers have revealed that weak feedback can induce the generation of sidebands separated by 1-3 GHz from the primary optical mode [1,2]. An interesting but unexplained observation was that, for external cavities longer than several millimeters, the sideband frequency did not depend on the length of the optical feedback path. The new analytical and numerical results reported in this paper indicate that feedback-induced high frequency intensity pulsations in single mode diode lasers are caused by the carrier-dependent modal refractive index of the laser cavity. These results fully explain the above observations and establish a simple, yet general, framework for understanding the origin of feedback noise in diode lasers coupled to external cavities of arbitrary length.
Longitudinal Mode Spectra of Diode Lasers
Authors: Streifer W. , Scifres D. R. , Burnham R. D.
Published: February 2023

Among the many factors(1) considered as influencing the longitudinal mode spectra of diode lasers are inhomogeneous broadening(2), lateral charge inhomogeneity(3), intensity induced longitudinal charge periodicity(4) and spontaneous emission driving the longitudinal modes(5). Our results show that spontaneous emission suffices to explain the experimental results for well-behaved homogeneously broadened lasers operating in a single transverse mode. These include spectral envelope narrowing which occurs as a laser is pumped from well below to well above threshold and the differences between real refractive index and gain-guided lasers.
Controllable Single Mode Operation in a Twin-mesa GaAs-(AlGa)As Laser Integrated with a Passive Waveguide
Authors: Zong-yao Xiao , Pen-nian Shen , Hui-zhen Pan
Published: February 2023

Single-mode optical fiber communication systems demand lasers to operate in a single longitudinal and fundamental transverse mode. Therefore, various single-mode lasers have recently been studied and fabricated(1), and the stable single-mode operation for a laser under high speed modulation has been realized by means of optical injection locking(2). This paper describes a twin-mesa GaAs-(AlGa)As laser integrated with a passive waveguide, which can be controllablly ocsillated in a single longitudinal and fundamental transverse mode with a Δλ of about 1-1.6 Å.
A Novel Multilayer Avalanche Photodetector for Low Noise Applications
Authors: Capasso F. , Tsang W. T. , Hutchinson A. L. , Williams G. F.
Published: February 2023

A large ionization rates (α,β) difference is an essential requirement for a low noise avalanche photodiode (APD). Unfortunately most III-V semiconductors have α≃β.
Novel High Speed Silicon Photodetector With Tunnel-barrier Layers.
Authors: Thaniyavarn Suwat , Gustafson T.K.
Published: February 2023

We demonstrate a new type of high speed silicon photodetector having a symmetric Metal/Tunnel-oxide/Silicon/Tunnel-oxide/Metal structure. A schematic cross-section of the device is illustrated in Figure (1). A silicon dioxide layer of approximately 45-60 angstroms is thermally grown on a lightly-doped P-type silicon wafer. A top view (Figure (2)) shows the aluminum electrodes forming an interdigital pattern over the relatively large circular active region (150 micrometers in diameter), while keeping junction capacitance small so that it does not limit the response speed of the detector (1-3). Both electrodes and the gaps are 5 micrometers wide.
Passive Guided-Wave Optical Components
Authors: Kobayashi Morio , Takata Hisao
Published: February 2023

This paper reviews the state-of-the-art for passive guided-wave optical components except for semiconductor components for optical communication systems in Japan. Bulk optical, microoptic and guided-wave optical components have been researched and developed so far. Bulk optical and microoptic components have been successfully made mainly for multimode transmission systems. Some of multimode guided-wave components have been studied to ease fabrication. Much effort has been made to single mode guided-wave components, but they have not yet been put to practical use. Here, isolators, modulators, switches, demultiplexers and star couplers are discussed.
InP Electro-Optic Directional Coupler Switch
Authors: Menigaux L. , Carenco A. , Linh N.T.
Published: February 2023

The properties of the GaInAsP/InP material system have been extensively explored and applied to a wide range of optoelectronic devices which could be used for 1-1.6μm optical fiber communications. Very recently, measurement on bulk InP has revealed an electro-optic effect of the same order of magnitude as that present in GaAs1. We have taken advantage of this property to fabricate another InP guided-wave device, an electro-optic directional coupler (EDC).
Time-Integrating Correlator Using Guided-Wave Anisotropic Acoustooptic Bragg Diffraction and Hybrid Integration*
Authors: Liao K. Y. , Lee C. C. , Tsai C. S.
Published: February 2023

Time-integrating correlation using bulk-wave isotropic acoustooptic (AO) Bragg diffraction has become a subject of great interest because of its applications in radar signal processing and communications.(1) Some encouraging results with the experiments which utilize guided-wave isotropic Bragg diffraction was reported earlier.(2) Subsequently, hybrid and monolithic structures for integrated optic implementations were suggested.(3,4) In a conventional configuration that utilizes either bulk-wave or guide-wave isotropic Bragg diffraction, a pair of imaging lenses and a spatial filter are used to separate the diffracted light beam from the undiffracted ligth beam. In this paper we report on a new and novel hybrid structure which utilizes guided-wave anisotropic Bragg diffraction involving te0 and tm0 modes in a Y-cut LiNbO3 waveguide. This new structure can conveniently incorporate a thin-film polarizer to separate the diffracted light from the undiffracted light prior to detection and, therefore, eliminates the need of imaging lenses and spatial filter. As a result, the acoustooptic time-integrating correlator (AOTIC) is not only much smaller and capable of providing superior performance figures, but also easier to be implemented in integrated optic format.
Performance of a Serrodyne Optical Frequency Translator
Authors: Wong K.K. , Wright S. , De La Rue. R.M.
Published: February 2023

There is considerable interest in the use of optical fibres as sensors(1), in which the propagation of light in the fibre is perturbed by some external influence. A homodyne interferometer is often used to convert a velocity perturbation into an intensity change. However, there are considerable advantages in using heterodyne techniques to translate the phase change to some intermediate frequency, including a greater sensitivity and the prospect of a digital output(2).
Optically Induced Refractive Index Change in Ti:LiNbO3 Strip Waveguides - Simple Quantitative Determination Using an Integrated Optical Directional Coupler.
Authors: Hoffmann D. , Langmann U.
Published: February 2023

Optical damage in LiNbO3crystals - i.e. refractive index change after exposure to laser radiation - is well-known as a phenomenon impairing the operation of integrated optical (i.o.) devices. Previous work aimed at directly measuring the build-up of the associated electric field with an external probe /1/. Schmidt et al. /2/ observed optically induced cross-talk in LiNbO3i.o. directional couplers. The new technique investigates the shift of the directional coupler switching characteristic at 1.06 μm wavelength after precedent exposure to radiation of 633 nm wavelength.
Single-Mode GaInAsP Optical Waveguides*
Authors: DeMeo N. L. , Leonberger F. J. , Groves S. H.
Published: February 2023

There is considerable interest in the development and applications of GaInAsP/InP sources and detectors. However, there has been no report to date of single-mode guided-wave optical components in this materials system. Such guided structures are necessary to develop contemplated monolithic structures where on-chip waveguiding is used to switch, modulate or direct light between sources and detectors. We report here the fabrication and testing of the first single-mode GaInAsP optical waveguides. The devices fabricated are rib guides formed on low-concentration LPE layers grown on InP substrates. The propagation loss is found to be 1.7 cm−1 at 1.3 µm and 2.3 cm−1 at 1.15 µm for layers with a 0.99-µm bandgap. While these losses are not as low as the 0.5 cm−1 value obtained for oxide-confined GaAs guides,1 the values are comparable to those obtained for single-mode heterostructure GaAlAs waveguides,2 and are the initial measurements of below-band-edge absorption in GaInAsP.
Temperature Dependence of Threshold Current and Efficiency of GaInAsP/InP Long-Wavelength Lasers Related to Intervalence Band Absorption and Other Nonradiative Carrier Leakage and Recombination
Authors: Suematsu Yasuharu , Asada Masahiro
Published: February 2023

The temperature dependence of the threshold current and the efficiency of GaInAsP/InP lasers was discussed including all possible mechanisms which can cause the strong temperature dependence of the threshold current. It was shown that the break in the temperature-threshold curve is mainly due to the intervalence band absorption. The influence of laser parameters is discussed.