bluuebunny/crossref_metadata_2025 huggingface dataset:
Review of Optical-Microwave Interaction Technology
Authors: Yen H. W. , Figueroa L. , Slayman C.
Published: February 2023

Optical photons with energies higher than the bandgap energy of a semiconductor can excite electron-hole pairs in that material. Since the characteristics of almost all semiconductor devices depend heavily on the number of charge carriers available, strong interactions between the performance of the device and the illuminating optical signal can be expected. The use of an optical signal to control solid-state microwave devices has attracted the attention of many researchers recently. It is a promising method of providing high-speed control of microwave signals at relatively high power levels. In addition, it offers the advantages of near perfect isolation between the microwave circuits and the input control signals, resistance to electromagnetic interferences, and savings in space and weight through replacing microwave cables and waveguides by optical fibers.
In0.53Ga0.47As PIN-FET Photo-Receiver for 1.0-1.7µm Wavelength Fiber Optic Systems
Authors: Leheny R. F. , Nahory R. E. , Pollack M. A. , Beebe E. D.
Published: February 2023

Recent interest in long wavelength photo-detectors for fiber optic communications systems operating in the 1.0 to 1.7µm wavelength region has been directed at the possible utilization of a very low capacitance PIN photodiode coupled directly to a low noise FET amplifier.1 We report on the properties of PIN photodiodes fabricated from In0.53Ga0.47AS material which meet the requirements for this PIN-FET photo-receiver application.
Si Detector Array for AlGaAs Laser Array
Authors: Scifres D. R. , Ponce F. A. , Stutius W.
Published: February 2023

Monolithic linear arrays of semiconductor injection laser devices are useful for a variety of applications including transmitting parallel channels of data along an array of fiber lightguides [1], and high-speed beam scan recording on a photoconducting material [2]. These applications, however, require that the light output powers of each laser in the array be very uniform in intensity so that each channel operates with the same signal-to-noise ratio. This places extremely stringent and often unrealistic requirements on the uniformity of lasers in the array. Alternatively, the light output power of each laser in the array can be individually monitored and used to control the laser current, thus holding the light output power constant. In this paper we demonstrate the feasibility of a very simple, low-cost technique for monitoring the light output power level of each laser in a monolithic linear array, thus making the use of a laser array practical in actual systems applications.
Electrooptic Polarization Modulation in Multielectrode AlxGa1-xAs Rib Waveguides
Authors: Reinhart F. K. , Logan R. A. , Sinclair W. R.
Published: February 2023

We report on a single mode rib waveguide (RWG) polarization modulator (POLAM) with a mode power modulation depth ≈ 0.99, an extinction ratio ≥ 27dB, a halfwave voltage Vπ≲ 12.5V at the test wavelength λ = 1.064μm, and a projected insertion loss∠ 1.5dB. The POLAM consists of a RWG formed on AlyGa1-yAs (y= 0.15) single heterostructure waveguide with AlxGa1-xAs (x=0.2) cladding grown on (110) oriented GaAs substrates. The electrodes are separated by about 1.2mm, as discussed below, and consist of a highly conductive low optical loss CdO layer with a gold overlay. Capacitance values of ≈ 0.5pF are estimated per RWG electrode for a two electrode section switch.
Optimization of Bit Rate in Optical Fiber Using Optical Solitons
Authors: Hasegawa Akira , Kodama Yuji , Taha Thiab R.
Published: February 2023

An optical soliton is a stationary nonlinear pulse which propagates in a monomode fiber in the presence of a (anomalons) dispersion. The existence of soliton in a glass fiber was predicted by Hasegawa and Tappert [1] in 1973 and was experimentally demonstrated by Mollenauer et al. [2] in 1980. The balancing power Po for formation of a soliton is inversely proportional to the square of the pulse width 2to and proportional to the group dispersion λ2∂2n/∂λ2 (<0)°, [3], where ωo is the angular frequency of the carrier and S is the cross sectional area of the core.
Integrated In0.53Ga0.47As PIN/FET Photoreceivers for 1-1.7 μm Wavelengths
Authors: Nahory R.E. , Leheny R.F. , Beebe E.D. , DeWinter J.C. , Martin R.J.
Published: February 2023

Since the report of the first In0.53Ga0.47As PIN/FET integrated optoelectronic device1 at the 1980 Integrated Optics Meeting many improvements have been made. Progress in materials and fabrication technology has resulted in increased JFET transconductance values of 50 mS/mm for a gate length of 7 μm, while at the same time maintaining a low dark current PIN photodiode (<100 nA). A wide variety of devices with different doping levels and geometries have been prepared. The characteristics of these devices will be presented and investigations of parameter values required for simultaneous optimization of the PIN photodetector and the coupled JFET will be discussed.
Etched Mirrors, Grooves, and Surfaces for GaInAsP/InP Integrated Optical Devices using Stop-Etch Crystal Planes
Authors: Coldren L. A. , Furuya K. , Miller B. I. , Rentschler J. A. , Dayem A. H. , Mankiewich P.
Published: February 2023

The fabrication of integrated devices and the efficient mass fabrication of even single devices on GaInAsP/InP DH wafers suffers from the dependence on substrate cleaving to form all mirror surfaces. We have developed wet and dry etching procedures that for the first time provide reproducible, high quality planar facets on DH wafers. As discussed in preliminary reports,1,2 these procedures make use of etchants that effectively stop at certain desired crystal planes, thus providing extremely smooth and planar surfaces. Previous device work with etched facets3-5 has not made use of this property although crystallographic etches have been previously explored.6,7
Influence of Hot Carriers on 1.3 μm InGaAsP Light Emitting Devices
Authors: Leheny R.F. , Nahory R.E. , Shah J. , Temkin H. , DiGiovanni A.E.
Published: February 2023

We report the measurement of significant carrier heating in double-heterostructure InGaAsP/InP 1.3 μm light emitting diodes (LED s) and discuss our results in terms of the processes which have been proposed to explain the performance characteristics of LED's and lasers fabricated from this alloy material. In particular, Auger recombination1-3 and intervalence band absorption4 are two mechanisms which have been separately proposed to explain the temperature dependence of threshold and quantum efficiency for lasers and the sublinear output variation with drive current for LED's. A common feature of each of these mechanisms is the generation of hot carriers having an energy of approximately Eg with respect to the band edge (see Fig. 1a). Our results5 demonstrate that indeed hot carriers are being generated and in sufficient numbers to maintain the entire free carrier system at an elevated temperature with respect to the lattice.
Coherent Optical Communication
Authors: Midwinter J E
Published: February 2023

Virtually all fibre transmission systems up to the present have used simple intensity modulation of the transmit laser, most frequently in the form of binary ON/OFF modulation. At the receiver, incoming optical power has been converted directly to photocurrent in a photodetector. Such receivers typically operate with sensitivities of 2000 photons/bit for 1E-9 bit error rates at 1300 or 1500nm wavelength, approximately 20dB away from the theoretically ideal photodetector performance. The only technique that has succeeded in closing this gap to date is that of the coherent system, using an optical local-oscillator at the receiver to operate with a photo-detector mixer in heterodyne or homodyne mode. Apart from the receiver, the transmitter design must be radically changed also and, ultimately, the technology seems likely to lead to new ways of using light for communications.
Multimode Lightwave Components with 2-D Arrayed Planar Microlens
Authors: Oikawa M. , Iga K. , Misawa S.
Published: February 2023

There has been a problem on the mass-productivity of lightwave components, since very precise optical alignment and coupling are required. In order to overcome this problem, we proposed stacked planar optics1 where lightwave circuits are integrated with 2-D arrayed configuration by stacking 2-D array of optical devices and planar microlenses2. In this paper we describe, first, a newly developed 2-D array of planar microlens with reasonable size and N.A. applicable to wide variety of lightwave technical fields, and second, present some measured optical characteristic and finally demonstrate a branching component by the use of a microlens array.
Integrated Optic Switching Circuit Using Ti:LiNbO3 Waveguide Network
Authors: Nakajima H. , Sawaki I. , Seino M. , Asama K. , Horimatsu T. , Murakami K.
Published: February 2023

Previously we have developed a bipolar-voltage-controlled optical switch using Ti:LiNbO3 intersecting waveguides [1]. Figure 1 shows the schematic structure and typical modulation characteristics of bipolar-voltage-controlled optical switch (bipolar switch) fabricated in Z-cut Ti:LiNbO3. The bipolar switch has the advantage of reduced switch element length and simplified multichannel integration compared with Δβ-reversal type directional coupler switch [2].
Acoustooptic Interaction in A LiNbO3 Spherical Waveguide
Authors: Li Q. , Tsai C.S. , Sottini S. , Lee C.C.
Published: February 2023

Recent progress on both fabrication techniques and performances of optical waveguides and individual active devices have been most significant. Nevertheless, undesirable performance of the present planar waveguide lenses remains to be one of the major obstacles toward eventual realization of planar integrated optic modules and circuits for wideband signal processing applications. The present planar waveguide lenses suffer from undesirable performance characteristics that include small light beam aperture, high optical loss, critical tolerance in lens placement and separation, and long focal length. Large focal length will result in a large substrate size and, thus, high optical through-put loss, severe waveguide scattering, and high ultimate cost. In this paper we report on a LiNbO3 spherical waveguide structure that simultaneously serves to guide, collimate, and focus the light beams.
Three Channels Buried Crescent InGaAsP Laser with 1.51 μm Wavelength on Semi-insulating InP
Authors: Koren U. , Arai S. , Tien P. K.
Published: February 2023

Laser diodes operating at the 1.5 μm wavelength region can find important applications for long distance optical fiber communication systems. In this letter we report a recently developed three channels buried crescent (TCBC) laser structure operating at 1.51 μm wavelength. This laser structure is similar to structures reported earlier1,2 for 1.2-1.3 μm wavelength operation, but with some modifications necessary to achieve good performance at 1.51 μm wavelength. In the present structure two additional channels are etched on both sides of the laser waveguide channel before the Liquid Phase Epitaxy (LPE) growth process. Because of rapid LPE growth at the edges of these channels, the growth rate is reduced at the central laser waveguide channel. This is important for achieving better control over the thickness of the 1.51 μm InGaAsP active region which has higher growth rates than the 1.3 μm InGaAsP layers.3
Initial Characterization of an Electrooptic Grating Multiplier
Authors: Verber C. M. , Kenan R. P. , Busch J. R.
Published: February 2023

We have suggested a variety of planar integrated optical matrix-vector and matrix-matrix(1) multipliers based upon the successive diffraction of an optical beam to produce an analog intensity which is proportional to the product of the two diffraction efficiencies. The active elements employed in these devices are pairs of cascaded electrooptic grating modulators. In particular the so-called "herringbone" configuration, in which two modulators share a common spine, is a particularly compact and self-aligned structure. We report the first data characterizing such a structure and show how, on the basis of this data, the electrode design can be improved to reduce crosstalk and to improve dynamic range. We then indicate how the improved herringbone electrode can be used in a matrix-vector multiplier employing the engagement architecture(2).
Self-sustained Picosecond Pulse Generation in a GaAlAs Laser at an Electrically Tunable Repetition Rate
Authors: Lau K.Y. , Yariv A.
Published: February 2023

Picosecond pulse generation from semiconductor lasers at high repetition rate is generally accomplished by two different means: mode-locking or direct electrical excitation. The shortest ever pulses of below lps was generated from a passively mode-locked GaAlAs laser [1], while active mode-locking produces somewhat longer optical pulses. The pulse repetion rate of the mode-locked laser is determined by the length of the external cavity and cannot be varied easily. The rather critical optical alignment necessary for operating the laser in an external cavity makes these mode-locked semiconductor lasers somewhat inconvenient in practical applications. A second means of picosecond pulse generation is by directly pumping the laser with intense, short electrical pulses [2,3] or by large amplitude sinusoidal current modulation [4,5]. Optical pulses generated by such means have pulse widths in the vicinity of 15-35 ps. This scheme requires an external RF source for exciting the laser. In this work, we will show that by using a state-of-the-art high speed laser in the optoelectronic feedback configuration shown in Fig. 1, highly stable optical pulses (with jitters of <10fs), with pulse widths between 10 and 20 ps can be generated, with a very high repetition rate from 1 5GHz which can be electrically tuned. This scheme has the advantage of eradicating the necessity of any external RF drive and/or sensitive optical alignment.
Design, Fabrication and Characterization of Horn Antennas in Ti-indiffused LiNbO3 Channel Waveguides*
Authors: Rediker R. H. , Lind T. A. , Becker R. A. , Johnson L. M.
Published: February 2023

This paper reports the first measurements of the far-field "antenna" patterns of integrated-optics horns both as receivers and transmitters and compares the experimental results with near-field mode patterns and with theory. Horn "antennas" in LiNbO3 are useful for matching field patterns of components being coupled to single-mode LiNbO3 waveguides and for increasing the collection efficiency of the wavefront sensor described below. These measurements also further the basic understanding of the operation of these horns.
Depolarization in Glass Waveguides
Authors: Garmire E. , Honda K.
Published: February 2023

We report depolarization in glass channel waveguides due to deviations in waveguide sidewalls. The measurement of depolarization is of concern for integrated optics devices such as beam splitters which use isotropic materials in applications requiring polarization preservation.
Use of Ti-indiffused LiNbO3 interferometric modulators for high-voltage transient measurements
Authors: Thayer D. , Graser M. , Virchow C. , Gallegos C. , Becker R. A. , Leonberger Fred J.
Published: February 2023

We report a study of the high-voltage capability and electrooptic linearity of Mach-Zehnder interferometric modulators. These properties are important for determining modulator performance limits for numerous signal-processing applications. Here the properties are evaluated in the context of one such application, the measurement of fast high-voltage (>100-V, ~300-ns) transient signals whose amplitudes cover several orders of magnitude. The key results of this study are the demonstration of both a high degree of linearity (<1 % deviation) and a very high-voltage capability (7 × 105 V/cm) for LiNbO3 guided-wave interferometric modulators. To our knowledge this is the first report of both of these modulator properties. We also describe an observed decrease in throughput and modulation depth at very high electric fields, which is attributable to optical mode attentuation effects.
Serrodyne frequency translation with high side-band suppression
Authors: Johnson L. M. , Cox C. H.
Published: February 2023

Guided-wave optical frequency shifters are being developed for a variety of applications. Some systems, such as the phase-nulling optical fiber gyroscope, require only moderate frequency shifts of up to several megahertz but with high side-band suppression. Serrodyne frequency translation is attractive for these applications. Here we present experimental results on a Ti:LiNbO3serrodyne frequency translator which utilizes a single-polarization waveguide design and a specialized sawtooth drive circuit. Overall side-band suppression of 42 dB was achieved for frequency shifts up to 40 kHz. This is the highest known overall side-band suppression yet reported for such a device.
Experimental investigation of stress in ion-exchanged glass waveguides
Authors: Brandenburg A.
Published: February 2023

Ion exchange in glass often produces stress in the glass surface. This is well known from potassium-sodium exchange, which is used for strengthening glass.1−3
Diffused channel glass waveguide optical splitters
Authors: Cline Terry W.
Published: February 2023

Diffused channel waveguides in planar glass substrates have been fabricated by groups in many countries.1-5 A process for making multimode waveguides with propagation losses of <0.05 dB/cm and fiber-waveguide coupling losses of ~0.25 dB/connection is reported here. The structure and properties of straights, 1×2, and 1×16 optical splitters are described.
Performance and reproducibility of Mach-Zehnder interferometer arrays in Ti: LiNbO3 operating at wavelengths from 0.458 to 3.39 μm
Authors: Rediker R. H. , Lind T. A.
Published: February 2023

Integrated guided-wave optical devices formed from Ti:LiNbO3 are being investigated for measurement and/or analog processing of optical wave fronts. An integrated optical device consisting of an array of interferometers and straight wave guides for wave front measurement is the first such device whose performance is being evaluated.’ Concepts on how to vary the phase contour and/or the intensity contour (apodize) of the wave front are under study. In analog processing high accuracy in the output (to up to three significant figures) is desirable. Thus uniformity and reproducibility are of paramount importance. This paper reports on this uniformity and reproducibility obtained for wave front measurement sensors. To show the applicability of Ti:LiNbO3 for analog processing throughout its transparent range of ≈0.4-4.0 μm, wave front measurement sensors have been fabricated for GaAs lasers (0.82 μm), IR He–Ne lasers (3.39 μm), and argon lasers (0.458 μm).
Narrow-Line width, Electro-Optically Tuned, Parallel Coupled Waveguide Laser
Authors: Korotky S.K. , Eisenstein G. , Heismann F. , Veselka J.J. , Marcatili E.A.J.
Published: February 2023

Single-frequency, narrow-linewidth, tunable lasers are required in applications such as spectroscopy, sensing, and coherent optical communications. We have previously proposed1 combining a semiconductor gain medium with titanium diffused lithium niobate (Ti:LiNbO3) waveguide devices to form compact lasers that permit electro-optic control of the output characteristics. This possibility was first demonstrated by actively mode-locking such a hybrid device1. Here we report the demonstration of the single-frequency and narrow-linewidth oscillation of a new InGaAsP-Ti:LiNbO3 extended cavity laser. The versatility and potential of this approach is illustrated by the integration on the single lithium niobate crystal of a parallel coupled cavity to assist the single longitudinal mode and narrow-linewidth operation, electro-optic elements for tuning the resonant frequencies of the cavities, and an external phase modulator for encoding data.
Titanium/Magnesium Double Diffusion Method For Efficient Fiber-LiNbO3 Waveguide Coupling
Authors: Komatsu K. , Kondo M. , Ohta Y.
Published: February 2023

Efficient fiber-waveguide coupling is indispensable in
LiNbO3 waveguide devices such as phase modulators for PSK
coherent systems. To reduce fiber-waveguide coupling loss, several
investigations, that try to optimize Ti diffusion parameters, have
been reported1)2). However, in these investigations,
fiber-waveguide-fiber insertion loss has been limited to 1 dB, because
of the asymmetry of the waveguide depth mode. Thus, the depth index
profile symmetrizing is essential to reduce fiber-waveguide coupling
loss.
Electron-beam microfabrication of optical gratings on polydiacetylene
Authors: Chen Y. J. , Carter G. M. , Brown S. W. , Sonek G. J. , Ballantyne J. M.
Published: February 2023

There has been an increasing interest in polydiacetylenes as nonlinear waveguide materials. Although a number of crystal growth techniques can be used to process the polydiacetylene polymers into a planar waveguide form (e.g., the Langmuir-Blodgett multilayer deposition technique and shear growth technique1), there is a lack of fabrication methods to create optical components in these guides. We report the successful fabrication of optical grating structures by direct electron-beam writing on the polymer. The technique can also be used for microfabrication of other integrated optics components, e.g., channel waveguides.
Design trade-offs for high-performance phase modulators in LiNbO3
Authors: Auracher Franz , Noll B.
Published: February 2023

Due to recent success in optical heterodyne transmission experiments there is increasing interest in high-performance phase modulators. We have, therefore, performed calculations on the optimum design of Ti-diffused LiNbO3-waveguide modulators. We have considered traveling wave modulators in c- and y-cut crystals with symmetric and asymmetric coplanar electrodes (Fig. 1). As the calculations show that the asymmetric electrodes on c-cut crystals with TM-like excitation yield the best performance the results are given for this case.
Self-calibrated measurement of picosecond semiconductor laser pulse duration with internally generated second harmonic emission
Authors: Liu J. M. , Chen Y. C.
Published: February 2023

Ultrashort optical pulse generation with semiconductor lasers is currently of interest for such applications as high-bit-rate optical communications and very fast data processing. In the picosecond regime, the most commonly used technique of pulse duration measurement is the nonlinear intensity autocorrelation technique involving phase-matched second harmonic generation in a nonlinear optical crystal, such as a LilO3 crystal.
Far-field and spectral control of laser diode arrays using injection locking
Authors: Abbas G. L. , Chan V. W. S. , Fugimoto J. G.
Published: February 2023

The coupled-stripe diode laser array offers improved power and reduced beam divergence over conventional devices.1,2 However, operation of these arrays in a single longitudinal mode with simultaneous control of the far-field emission pattern has proved difficult. In addition to longitudinal modes, coupling of the multiple-emitting stripes in these devices produces transverse supermodes, each exhibiting different far-field behavior. One approach to this problem has been to control the supermode oscillation and thereby determine the far field. Previous researchers have demonstrated the use of an external grating cavity to obtain far-field tuning.3 Recently, injection locking has emerged as a promising technique for simultaneous spectral and far-field control.4
Monolayer detection with guided wave coherent anti-Stokes Raman scattering
Authors: Hetherington W. M. , Koenig E. W. , Van Wyck N. E. , Fortenberry R. M. , Stegeman George I. , Seaton C. T.
Published: February 2023

Nonlinear spectroscopy has become a very powerful tool for studying vibrational and electronic transitions in molecules.1 In particular, coherent anti-Stokes Raman scattering (CARS) has been predicted2 and demonstrated experimentally3 to be a very efficient process when performed with guided waves. We report experiments in which guided wave CARS was used to detect and identify monolayers of TiO2 on a Nb2O5 film surface.
Measurements of switching transients in high-speed semiconductor lasers
Authors: Tucker R. S. , Wiesenfeld J. M. , Downey P. M. , Bowers J. E.
Published: February 2023

Recent developments in high-speed semiconductor lasers with bandwidths approaching 20 GHz (see, for example, Ref. 1) offer the possibility of digital transmission at data rates in the 10–20-Gbit/s range. The modulation characteristics of these high-speed lasers are usually evaluated by small-signal measurements. However, the switching behavior under large-signal conditions determines the ultimate limits on high-speed digital modulation. Turn-on and turn-off delays, for example,2 can lead to intersymbol interference at high bit rates while overshoot and ringing give rise to undesirable frequency chirp.3
Ultrahigh-speed parametric modulation schemes of semiconductor lasers
Authors: Iga K. , Koyama F.
Published: February 2023

Since Ikegami and Suematsu1 reported the existence of resonancelike phenomena in direct semiconductor laser modulation, it has been assumed that the maximum modulation frequency is approximately the resonancelike frequency fr. Some other modulation methods, however,2–4 are hoping to achieve fast switching beyond the resonancelike frequency fr as schematically shown in Fig. 1. The maximum modulation frequencies for these schemes were preliminarily calculated using simple rate equations.5 The purpose of this paper is to clarify the ultrahigh-speed modulation capability of parametric modulation of semiconductor lasers.
High-sensitivity planar InGaAs avalanche photodiodes with preferential lateral extended guard ring for Gbit/s-range communication
Authors: Taguchi K. , Torikai T. , Sugimoto Y. , Makita K. , Ishihara H. , Fujita S.
Published: February 2023

InGaAs/InP avalanche photodiodes (APDs) are the most promising detectors for long-wavelength optical fiber communication systems.1–3 Moreover, planar APDs with a successful guard ring (GR) are demanded for practical use. This paper reports a newly developed planar InGaAs APD with a preferential lateral extended guard ring (PLEG).
An InP/InGaAsP/InGaAs avalanche photodiode exhibiting a gain-bandwidth product of 60 GHz
Authors: Holden W. S. , Campbell J. C. , Ferguson J. F. , Dental A. G. , Jhee Y. K.
Published: February 2023

Previously we reported on the pulse1 and frequency response2 of InP/InGaAsP/InGaAs avalanche photodiodes with separate absorption, grading, and multiplication regions (SAGM-APD). In this paper we describe several modifications we have made to the device structure, shown schematically in Fig. 1, to achieve significant improvement in both the frequency and pulse response. The changes include (1) reduction of the total depletion width to decrease the transit time of the free carriers, (2) use of low-resistance substrates to reduce the RC time constant, (3) introduction of an additional transition layer to eliminate effectively hole trapping at the heterojunction interfaces, and (4) increasing the carrier concentration in the multiplication region to reduce avalanche buildup time.
Low-Drive-Voltage GaAs/AIGaAs Quantum Well Waveguide Phase Modulators
Authors: Zucker J. E. , Hendrickson T. L. , Burrus C.
Published: February 2023

There has been much recent theoretical (1-3) and experimental (4-8) interest in the electrooptic effect in quantum well heterostructures. The size of the change in refractive index Δn and its quadratic dependence on applied electric field yield an advantage for quantum well phase modulators over bulk semiconductor devices in both power consumption and device length. We have shown that propagation loss and residual intensity modulation are minimized in quantum well phase modulators by operating below the bandedge at large wavelength detuning Δλ
X
from the excitonic absorption peak (8). At Δλ
X
= 400 Å, the propagation length required for pi phase shift

(

l
π

≡

λ

2
Δ
n

)

in a leaky waveguide structure containing two quantum wells was found to be 4.25 mm for a transverse field 9.5 × 10 4 V/cm (8). In this letter we show that much shorter device lengths l
π
can be acheived in a waveguide structure containing a larger number of quantum wells. For the same transverse field and detuning Δλ
X
we obtain l
π
= 220 μm. In addition, we demonstrate that the drive power required to produce a pi phase shift can be significantly reduced via the quadratic effect by appropriate DC biasing of the quantum well waveguide phase modulator. In this way, large phase shifts are obtained in lengths on the order of 100 μm for voltages under 5 V.
Temperature Dependence in GaAs/AlGaAs Multiple Quantum Well Waveguides
Authors: Chen Y. J. , Sonek G. J.
Published: February 2023

Opto-electronic devices, utilizing multiple quantum well (MQW) structures with room temperature excitonic resonances, have many performance advantages over conventional devices.1 Up to now, nearly all reported MQW devices are based on the resonant absorptive effect. These MQW devices are quite efficient and require very low electrical/optical operating power. Heating has not been a problem. However for complex applications which utilize high density of QW devices, operating at ultra-high data rate and/or under delicate detuning condition for feedback effects, the heating effect should not be overlooked. We report on a detailed experimental study of the temperature dependent (TD) optical properties of a GaAs/AlGaAs MQW waveguide near room temperature. We utilized a grating structure on the waveguide to couple into the waveguide modes, allowing us to study both dispersive and absorptive optical properties of the MQW waveguide.
Waveguide Modulator for Argon Laser consisting of Vapor-grown Single-crystal ZnSe on GaAs substrates
Authors: Jupina M.H. , Kim B.G. , Garmire E. , Shibata N.
Published: February 2023

We are investigating the possibility of waveguide modulators at argon laser wavelengths using ZnSe grown by OMVPE on GaAs substrates. The geometry of our preliminary device is shown in Figure 1. A single crystal film 8 um thick of ZnSe (n = 2.72) was grown on a buffer of ZnS0.08Se0.92 (n = 2.70) grown on [100] GaAs. This formed a planar waveguide for Argon laser light of dimension comparable to light guided from a single mode fiber. Parallel stripe electrodes of Au were vacuum deposited to form contacts (unannealed) to the semi-insulating ZnSe waveguide (resistivity was measured as 109 ohm-cm). The electrodes were 75 um apart. A short waveguide 0.635 mm in length was cleaved and argon laser light was focussed into and out of this guide with microscope objectives. The relative intensity of the guided light was monitored on a silicon detector. The initial devices were planar waveguides; lateral confinement was not required because of the short length of the sample and wide electrode spacing.
Bend Losses of Miniature Single Mode GaAs/AlGaAs Waveguides
Authors: Takeuchi Hiroaki , Oe Kunishige
Published: February 2023

Recently, much research has been performed on III-V semiconductor optical waveguides for application in optical monolithic integration. To realize effective monolithic integration of waveguides with active devices, such as lasers and modulators, the waveguides must be single mode, and the cross-sectional dimensions must be reduced. Therefore, strip-loaded miniature waveguides with strong optical confinement are very appropriate for this purpose. We have already reported a low-loss strip-loaded single-mode waveguide with a GaAs/AlGaAs double heterostructure1). This study describes bend losses in GaAs/AlGaAs miniature single-mode waveguides.
A Focusing Grating Coupler for Polarization Detection
Authors: Ura Shogo , Sunagawa Hiroshi , Suhara Toshiaki , Nishihara Hiroshi
Published: February 2023

A focusing grating coupler (FGC) is an attractive component in integrated optics, since it operates for both lens and waveguide-air interface. By using the FGCs, we reported several integrated-optic devices such as integrated-optic disk pickup [1]. In this paper, we propose and demonstrate a novel FGC having polarization detection function. This FGC is the key component for optical integration of magneto-optical (MO) disk pickup.
Diffusion of Protons in H+: LiNbO3 Waveguides from a Melt of Limited Volume
Authors: Vohra Sandeep T. , Mickelson Alan R.
Published: February 2023

Proton exchanged LiNbO3 optical waveguide fabrication [1] has attracted considerable attention because of the ease of fabrication, relatively low temperatures at which it can be carried out, large index difference (Δn ~ 0.12) it produces and the high optical damage threshold of the resulting guides. Several authors [2-3] have reported the diffusion analysis of such proton exchanged guides by measuring the depth of the waveguide d, as a function of exchange time t and then assuming the linear relationship d = [4D(T)t]1/2 to deduce the effective diffusion coefficient D(T). Such a linear diffusion relationship, which takes into account the constancy of proton concentration in the melt as the diffusion proceeds, predicts that the amount of protons in the crystal should increase linearly as a function of square root of exchange time. This would be the case if the melt is of 'infinite' volume.
Use of Integrated Guided-Wave Optics to Measure and/or Process Optical Wavefronts with High-Temporal Resolution*
Authors: Rediker R. H. , Lind T.A. , Burke B.E. , Zollars B. G.
Published: February 2023

The performance and reproducibility of Mach-Zehnder interferometer arrays of Ti: LiNbO3 and their use in measuring optical wavefronts were reported at the 1986 IGWO conference.1 This paper reports on arrays with improved uniformity and reproducibility. Measurements have been made with near three-significant-figure precision which is desired in some applications. The outputs of the arrays were coupled to a CCD imager and the input wavefront was measured as a function of time with a resolution as short as 200 nsec which was limited by the speed of the control circuitry of the CCD. These results indicate that large arrays of optical waveguide components can be use to process (e.g. focus) as well as measure optical wavefronts with high temporal resolution.
Multichannel Integrated Optic Device Modules in LinbO3 for Digital Data Processing*
Authors: Tsai C. S. , Zang D. Y. , Le P.
Published: February 2023

Numerous LinbO3-based integrated optic (IO) devices that utilize electrooptic (EO) or acoustooptic (AO) effect in either planar or channel waveguides have been constructed in recent years for future applications in optical communication and RF signal processing systems. However, most of these IO devices utilize a single or a small number of light sources and are, therefore, best suited to applications that involve a relatively small number of channels. In the meantime, it is of increasing interest to make IO devices that utilize a large number of light sources such as the diode laser array so that the very large channel capacities that are inherent in the diode laser, the optical fiber, and the photo-detector arrays may be conveniently expolited. Recently, successful fabrication of microlenses and microlens arrays (using the TIPE technique) [1] and channel-planar composite waveguides (using the TI process) [2] in LinbO3 has enabled us to construct a number of multichannel IO device modules. These device modules have been used to perform RF spectral analysis and analog computing [3,4]. In this paper, two such TIPE microlens-based multichannel device modules that were constructed most recently are reported. These two device modules represent the highest degree of integration that has been accomplished thus far, and are being used to carry out a variety of digital data processing and computing experiments.
Amplification of High Repetition Rate Picosecond Pulses Using An InGaAsP Traveling-Wave Optical Amplifier
Authors: Eisenstein G. , Wiesenfeld J. M. , Tucker R. S. , Raybon G.
Published: February 2023

Traveling wave (TW) optical amplifiers with high CW gains and wide band widths have recently been demonstrated at both 1.5 μm [1] and 1.3 μm [2] wavelengths. The use of optical amplifiers in ultra-high bit rate systems, such as those using optical time division multiplexing [3], requires knowledge of their gain characteristics for short (picosecond) optical pulse inputs. The amplification of short pulses has been demonstrated previously in various experiments using both GaAlAs and InGaAsP amplifiers [4-8]. All reported experiments used pulse repetition rates below 100 MHz. Moreover, only one past experiment [8] used an InGaAsP TW amplifier, but the pulses used were not very short (45-90 ps). We report here on the use of a 1.3-μm TW optical amplifier for amplification of picosecond pulses at a high repetition rate. We demonstrate distortionless amplification of 12-ps pulses at a repetition rate of 4 GHz. The amplifier gain was measured to be ~ 10 dB, corresponding to a chip gain of 21 dB, at a facet peak output power of 0.25 W.
Laser Micro-Fabrication of Ti:LiNbO3 Waveguide Devices
Authors: Krauss T. , Oprysko M.M. , Grebe K. , Fan B. , Speth A.
Published: February 2023

The processing of Ti-indiffused lithium niobate devices is not unlike the processing of semiconductor devices.1 The procedure involved to fabricate a waveguide in lithium niobate include: deposition of a blanket film of Ti, coating with resist, exposure through a mask, development of the resist, etching of the Ti and finally diffusion in a controlled atmosphere. The steps of delineating the waveguide features is time-consuming and is usually gated by the mask. This is especially true when the active area of research is usually the geometry of the guides themselves, i.e., the branching angles, radius of curvature, distance between guides, etc. A method using laser microfabrication techniques2,3 which eliminates many of these processing steps and makes possible the rapid design and fabrication of waveguide structures in LiNbO3 has been developed.
Experimental Characteristics of a Multiple-Quantum-Well-Coupled Nonlinear Directional Coupler
Authors: Keyworth B.P. , Cada M. , Glinski J.M. , SpringThorpe A.J. , Mandeville P.
Published: February 2023

Experimental results with a simple all-optical nonlinear directional coupler are reported. The element was fabricated by Molecular Beam Epitaxy (MBE) and is composed of two Al.18Ga.82As waveguides of 1.85-μm thickness, coupled through a 0.948-μm-thick MQW. The MQW consists of 30 periods of alternating 10.6-nm GaAs and 21-nm Al.33Ga.67As layers. The waveguides are planar without any lateral confinement. The whole structure was grown on a GaAs substrate and is buffered on both sides by a 2.05-μm-thick layer of Al.72Ga.28As composition. The structure is illustrated in Figure 1.
Nonlinear Optical Effects in Channel Waveguide Devices Fabricated in Semiconductor-Doped Glass
Authors: Banyai W.C. , Finlayson N. , Brown F. , Seaton C.T. , Stegeman G.I. , Cullen T.C. , Ironside C.N.
Published: February 2023

We have observed strong fluence-dependent transmission effects in Ka+/Na+ ion-exchange channel waveguide devices fabricated in semiconductor-doped glass. Single channels, directional couplers and asymmetric Mach-Zehnder interferometers were investigated.
High-Speed Ti:LiNbO3 Switch/Modulators: Recent Advances and Applications
Authors: Korotky Steven K.
Published: February 2023

High-Speed Ti:LiNbO3 phase, amplitude, and intensity modulators and space switches provide unique capabilities in optical communication and signal processing. We review progress on these devices including the areas of specialized designs, theoretical understanding, experimental system demonstrations, and possible uses.
Optical Switch Arrays in LiNbO3, Status Review and Prospects
Authors: Thylen Lars
Published: February 2023

Integrated optics devices inLiNbO3have reached a significant maturity in recent years, reflected in the emerging commercial availability of devices such as modulators and switches. The applications for these devices range from high speed modulation in coherent and noncoherent systems, receiver chips in coherent systems, sensors and instrumentation to photonic switching and signal processing. Switches, in particular, are important components, due to the basic character of the switching function in time and space. This paper treats reported switch arrays, as well as some demonstrated applications; prospects for further deveploment are briefly discussed.
Very Low Loss Waveguides and Efficient Modulators in InGaAsP/InP
Authors: Bourbin Y. , Enard A. , Blondeau R. , Rondi D. , Papuchon M.
Published: February 2023

Since III-V material have many applications in the field of optoelectronic components, low loss waveguides and low drive voltage modulators are considered to be key components for many future systems. Up to now, many efforts on material elaboration and technology have led to interesting waveguide characteristics (ref [1], [2], [3]) on ridge structures and on buried ones (ref [4]) with best reported propagation losses on the order of 0.4 dB/cm at 1.55 μm wavelength. Here we report on an improvement of those values (0.18 dB/cm) observed on 30.5 mm long straight waveguides and on the observation of linear and quadratic electrooptic modulation performed with those buried structures.
Fabrication methods for producing periodically domain-inverted waveguides in lithium niobate for second harmonic generation
Authors: Webjörn Jonas , Laurell Fredrik , Arvidsson Gunnar
Published: February 2023

The first demonstrations of frequency doubling in periodically domain-inverted LiNbO3 waveguides have recently been reported /1,2/. We discuss fabrication methods, the mechanisms involved in domain inversion, and suggest possible improvements in the fabrication process. The technique allows the possibility of generating blue light, by frequency doubling of semiconductor lasers, in a more efficient manner, i.e. guided to guided interaction.
Laser-Assisted Fabrication of Optical Waveguides in Gel-Silica Glasses
Authors: Miliou A. , Srivastava R. , Ramaswamy R. V. , Slocumb R. W. , Chia Taipau , West J
Published: February 2023

We report a technique for fabricating waveguides in gel-silica glasses by local densification of the substrate glass surface by a focussed laser beam. This is the first time that waveguides in pure silica have been fabricated! The advantages of the technique include the simplicity, amenability to complete automation, pattern delineation without recourse to photolithography and potential for fiber compatibility and monolithic integration.
Grating Assisted InGaAsP/InP Vertical Co-directional Coupler Filter
Authors: Alferness R. C. , Koch T. L. , Buhl L. L. , Storz F. , Heismann F. , Martyak M. J. R.
Published: February 2023

Presently there is great interest in lightwave networks based upon wavelength division multiplexing techniques. Such systems, as well other applications such as noise filters for optical amplifiers, will require compact, possibly tunable wavelength filter devices. In addition, further benefits may result if these devices could be monolithically integrated with photodetectors or optical amplifiers. Toward that goal we have demonstrated, for the first time, a wavelength selective coupler based upon forward coupling between nonidentical, vertically stacked InGaAsP waveguides on InP using an etched corrugated layer for phase matching. We have achieved a bandpass filter response with a 3 dB bandwidth (full width at half maximum) of 65Å with an interaction length of only 1.0 mm using a grating period of 14.4 μm.
Voltage-Length Product for Modal Evolution Type Digital Switches
Authors: Burns W. K.
Published: February 2023

The digital optical switch recently reported by Silberberg, et. al.1 has reactivated interest in devices that achieve switching via the evolution of normal mode shape in a waveguide branch, rather than the interference of normal modes in a directional coupler or a Mach-Zehnder interferometer. The active element of the digital switch, an active waveguide branch, was demonstrated by Burns, et. al.2 in a three port configuration. Our interest here is to develop an expression for the voltage-length product of an active waveguide branch, so that performance comparisons between the modal evolution devices and modal interference devices can be made. To do this we will utilize the analytic solution for normal mode coupling in specifically shaped waveguide branches3. This approach has two advantages: 1) It is an analytic solution and does not require computer analysis, and 2) the shaped branch assumed represents the optimum shape in that it is a minimum length structure for a given amount of mode conversion, i.e. it is the best you can do for a minimum voltage-length product. Finally we will compare the calculated V-L product with experiment.
BPM Anaiysis of SHG in Form of Cerenkov Radiation
Authors: Fujiwara T. , Izutsu M. , Murata H. , Tanabe Y. , Sueta T.
Published: February 2023

The second harmonic generation in form of Cerenkov radiation has attracted considerable attention, especially since the experimental demonstrations was performed using proton-exchanged LiNbO3 waveguides with YAG and GaAs lasers1. They have proved its effectivity and applicability in wide range of wavelength.
The Dependence of Guided Optical Wave Loss in Thin-Film ZnO on Induced Surface Defect Scattering Sites
Authors: Hickernell F.S. , Stringer S.R. , Hickernell T.S.
Published: February 2023

Scattering loss in optical waveguides has primarily been investigated theoretically (1-4) and very little quantitative measurement data has been available for comparison with the theory. Where experimental comparisons have been made (3,4), the measured guided optical wave losses were higher than would be attributed to surface roughness and other volume loss mechanisms were invoked to explain the discrepancies. In the investigation described in this paper, a base propagation loss level is established in a thin-film ZnO waveguide, surface scattering sites of known density and depth are created and the corresponding increase in optical loss is measured. To the authors knowledge this is the first quantitative measurement of surface scattering losses in optical waveguides where a systematic change in the depth of the scattering sites was induced.
Electrooptic Coefficient r33 in Proton-Exchanged z-Cut LiTaO3 Waveguides
Authors: Li Yu-Shan , Tada Kunio , Murai Toru , Yuhara Toshiya
Published: February 2023

It is well known that LiTaO3 offers an attractive alternative to LiNbO3 because of higher optical damage threshold level and smaller birefringence. Recently, optical waveguides fabricated by Zn diffusion in y-cut and z-cut substrates have been reported1). In this method, the zinc diffusion was carried out at 595°C below the Curie temperature for 115 or 240 hours. There are also reports on proton-exchanged waveguides in x-cut2) and z-cut3) substrates successfully fabricated at lower temperature in much fewer hours.
Binary Optics: a New Tool for Lens Designs
Authors: Veldkamp Wilfrid B.
Published: February 2023

Binary optics offers design freedom in "synthetic" dispersion free materials and in surface profiles. Savings in weight, quality improvements, and future applications will be discussed.
Binary optics from a raytracing point of view
Authors: Southwell William H.
Published: February 2023

Surfaces which achieve optical power from prescribed surface relief profiles (called kinoforms) have been generally described in the literature1-3 as diffraction devices, probably because of their similarity to holograms. The design and evaluation of these lenses are performed by either modeling the surface as a very high index lens4,5 or by using a raytrace code to define an arbitrary phase surface expressed as a polynomial. These methods do not utilize the full aberration correction capability of the relief profile when it is defined from a zonal raytrace refraction design. For example, the optimum relief profile for a kinoform surface2 focussing collimated light is a conic with conic coefficient of -n2 and with a different curvature in each Fresnel zone. Such a surface has discontinuous slopes at the zone boundaries even before the surface is given the two pi phase jumps. The above methods of design do not provide for discontinuous slopes.