bluuebunny/crossref_metadata_2025 huggingface dataset:
Large Electroabsorption Effect in InGaAs/InP Multiple Quantum Well Waveguide Modulator Grown by MO-CVD
Authors: Wood Thomas H. , Carr Elizabeth C. , Burrus Charles A. , Miller Barry I. , Koren Uziel
Published: February 2023

Active optoelectronic devices made from semiconductor multiple quantum wells (MQWs) have been attracting much attention recently because of the large optoelectronic properties observed in these materials. For example, an electroabsorption effect in GaAs/AlGaAs MQWs[1] has been observed with a change in optical absorption coefficient as large as Δα = 15,000 cm−1. Recently, much progress has been made in applying this technology to long-wavelength materials. For example, a GaSb/AlGaSb[2] waveguide modulator was reported with a Δα = 5500 cm−1 at a wavelength of λ = 1.55 μm. A waveguide device made from GaInAs/InP MQWs[3] that had Δα = 400 cm−1 at λ = 1.55 μm, and produced an on/off ratio R = 8:1 has been reported. Also, a waveguide device with an insertion loss as low as 2.9 dB in InGaAs/InP MQWs[4] at λ = 1.67 μm has been reported, but the 47:1 on/off ratio was achieved in a waveguide that was fairly long (L = 375 μm), and the Δα was only 640 cm−1. For applications in high-performance lightwave systems, shorter devices with larger Δα are necessary so that higher speeds can be achieved.
Two-step thermal ion exchange process for single-mode waveguides embedded in glass
Authors: Seki Masafumi , Sugawara Ryoichi , Hashizume Hideki
Published: February 2023

High-capacity fiber optic transmission systems with single­mode fibers (SMFs) require single-mode optical devices. Various works have been carried out to make single-mode waveguides in glass by ion exchange (I/E) processes. These procedures may be thermal I/E, electric field-assisted I/E as well as one-step I/E and two-step I/E processes. The one-step I/E process [1,2], in general, cannot provide embedded waveguides and therefore is less attractive from the point of view of practical applications. One the other hand, by using a two-step electric field-assisted I/E process[3], one can fabricate embedded single-mode waveguides. However, for electric field-assisted I/E processes, a special experimental set-up is necessary where plus- and minus-potential molten salts are kept isolated from each other. While the two-step thermal I/E process with only the K ion[4] seems to be straightforward and the waveguide structure is not an embedded type but an inverted ridge guide.
High Index, Low Loss Waveguides in LiNbO3 with Ti Ion Implantation
Authors: Ashley Paul R. , Chang William S. C. , Buchal Chris J.
Published: February 2023

Optical waveguides have been produced for many years in LiNbO3 by diffusing Ti metal from a thin deposited film at high temperature.1 These waveguides have been the subject of much research and refinement.2 For many applications, particularly those using relatively long wavelengths (1.3,1.5 microns) for optical communications, the low index change Δn and resulting large cross-sectional area of the diffused waveguide limits the efficiency of the electro-optic devices. Reported here is the development of a new technique for making optical waveguides in LiNbO3 by directly implanting Ti. A solid phase epitaxial regrowth process2 was employed to restore the amorphized crystal structure, making low loss guides (<1dB/cm) possible. Large Δn and small diffusion length can be achieved in this process that will improve significantly the efficiency of electro-optic guided wave devices.
Narrowband Double-Pass Wavelength Filter with Broad Tuning Range
Authors: Heismann F. , Warzanskyj W. , Alferness R. C. , Buhl L. L.
Published: February 2023

Wavelength multiplexed fiberoptic networks require broadly tunable narrowband wavelength filters that are compatible with single-mode fibers. In this paper we demonstrate an integrated-optical bandpass filter for 1.5 µm with a bandwidth of only 6 Å and a tuning range of at least 160 Å.
ThF4-Buffered GaAs Waveguide Modulators for CO2 Lasers*
Authors: Farina J. D. , Brown R. T. , Cheo P. K.
Published: February 2023

While much of the GaAs integrated optic work has been directed at 1 um fiber optic applications, another exciting area is in laser system applications. In particular a wideband modulator operating as a frequency shifter for 10.6 um that has attractive bandwidth, efficiency and power handling is of much interest. Here we report on the design and development of advanced modulator structures of this type operating at microwave frequencies between 8 - 18 GHz. A previously reported device (Ref. 1) consisted of a semiconductor thin film slab waveguide with metal electrodes applied directly on the top and bottom. The major short coming of this geometry was the high Insertion loss due to absorption by the metal layers. To avoid this problem it was necessary to place a low index buffer material between the waveguide and metal. While ideal geometry would consist of an epitaxially grown structure of GaAs and GaAlAs, difficulties in producing high quality epitaxial layers resulted in excessive free carrier loss. We alternatively considered the use of ThF4 as the buffer material and have recently been successful in reducing the insertion loss of the device. As will be discussed, these layers also offer some added flexibility which we have exploited to improve the overall optical and microwave design of the device.
Low Loss and Low Drive Voltage Electrooptical Phase Modulator at 10.6 Microns
Authors: Delacourt D. , Blondeau R. , Brylinski C. , Di Forte-Poisson M.A. , Papuchon M.
Published: February 2023

In general, the semiconducting electrooptical devices based on the Integrated Optics technology, present a low doped guiding region where the electric field is applied. This region is sandwiched between to highly doped (or metallic) media which permit to apply this field |1|. The smaller the thickness of this guiding region is, the lower the drive voltage is but the higher the propagation losses are because of a more important overlap between the optical mode and the free carriers of the extreme media. Moreover in the mid-infrared region, this influence of free carriers on propagation losses in semiconductors is very important. So, a trade-off has to be found to combine low losses and low drive voltage that have up to now only been demonstrated separately |2|, |3|, |4|. The phase modulator described below has been realized to optimize both parameters simultaneously. This device is based on a two-dimensional waveguide and presents together performances below 2 dB/cm and around 100 Volts for the propagation losses and the drive voltage Vπ respectively.
Thermal Tapering of Ion-Exchanged Channel Guides in Glass
Authors: Mahapatra A. , Connors J.M.
Published: February 2023

Ion-exchange in glass produces guides with a large increase in refractive index (∆n = 0.1) and low propogation loss. Hence the technique is useful for devices requiring tight confinement such as ring resonators(1),(2) and passive power dividers(3). The large ∆n, however, results in large mode mismatch between single mode channel guides and fibers. A typical single mode, ion-exchanged channel guide in glass has a width of 2μm. It is not possible to mode match to a fiber merely by tapering the width to 5-10μm at the device input since this makes the input end multimode. An alternate approach is to thermally taper the channel guide by postbaking it in a suitable temperature gradient. Thus the guide dimension at the input end is increased to 5-10μm; however, Δn decreases since the exchanged ion species is distributed over a larger volume and the guide remains single mode.
A Simplified Method of Calculating Power Transfer between Nonparallel Dielectric Waveguides
Authors: Pedersen Paul , Nightingale J. L.
Published: February 2023

Practical directional couplers have nonparallel waveguide regions where significant power transfer occurs. Such power transfer is generally calculated by numerical integration 1. We report on a simplified method using a multiplicative factor which depends on the generic waveguide path. Use of this method allows rapid determination of the power transfer in nonparallel waveguide regions, which facilitates directional coupler design.
A highly sensitive excite and probe technique to measure optically induced refractive index changes in Ti:LiNbO3 -waveguide resonators
Authors: Volk R. , Sohler W.
Published: February 2023

Introduction. Severe limitations for the application of Ti:LiNbO3 optical (channel) waveguides especially in phase sensitive devices are set by the susceptibility of this material to optically induced changes of the (effective) indices of refraction (optical damage). Therefore several groups have thoroughly investigated this photorefractive susceptibility using different methods and waveguide devices such as asymmetric Mach- Zehnder interferometers, directional couplers and straight waveguides [1-3]. In planar waveguides using a holographic method optically induced changes of Δn ≃ 10−6 could be measured [4]. The understanding of the photorefractive effects in Ti:LiNbO3 waveguides has been considerally improved by the cited work. Nevertheless, an even more sensitive method is required to study these effects, as recent developments of waveguide fabrication techniques like codoping, ion exchange, outdiffusion and substrates of higher purity have reduced the damage susceptibility considerably. A method is needed which allows a quantitative assessment of the quality of — in particular channel — waveguides with respect to their photorefractive susceptibility.
A Tree-Structured 4×4 Switch Array in Lithium Niobate with Attached Fibers and Proton-Exchange Polarizers
Authors: Milbrodt M. A. , Veselka J. J. , Bahadori K. , Chen Y. C. , Bogert G. A. , Coult D. G. , Holmes R. J. , Erickson J. R. , Payne W. A.
Published: February 2023

Recently, several integrated LiNbO3 optical switch arrays have been reported [1] [2] [3] [4], most of which have used the crossbar configuration. Here, we present the design and results of a 4 × 4 switch array using a new non-blocking architecture, the duobanyan. The duobanyan architecture has three banks of switches (see Figure 1). The signal passes through three switches independent of path. The device was measured using the TM polarization at λ=1.3μm. Proton-exchange (PE) polarizers and polarization-maintaining fibers were attached, improving the crosstalk performance of the switches.
Suppression of Sidelobes in Far-Field Radiation from Non-uniformly-spaced Waveguide Arrays for Optical Beam Steering
Authors: Abeles J. H. , Keramidas G. , Chan W. K. , Deri R. J. , Hawkins R. J.
Published: February 2023

High-speed, wide-angle, free-space optical beamsteering by coherent arrays is attractive for applications such as optical interconnects, switching, and displays, but previously proposed uniform arrays radiate undesirable sidelobes in addition to the main lobe. In this work, we show both experimentally and theoretically that sidelobes can be dramatically suppressed by arraying emitters in a non-uniform pattern. Sidelobe suppression in a 12-element reactive-ion-etched GaAs homostructure waveguide array was obtained in close agreement with theory. The optimum spacing is closely approximated by a gradual, linearly-increasing doubling in interelement spacing across the array. A 100-element array of minimum spacing 5 μm, practical with present semiconductor waveguide technology, can attain a 30:1 reduction in sidelobe intensity with a 0.08° FWHM main lobe.
Payoffs of Integrated Optics Technology to Fiber Optic Sensor Systems
Authors: De Paula Ramon P. , Minford William J.
Published: February 2023

Integrated optic (IO) device and circuits technologies will bring new capabilities to fiber optic sensor systems. This paper will discuss the advantages, problems and future issues of this implementation.
High Dynamic Range, Linear Modulators for Electric Field Sensing
Authors: Bulmer C. H. , Howerton M.M. , Burns W.K. , Hiser S. C.
Published: February 2023

An integrated-optical modulator is of use for electric field sensing as the active device can be small, minimally perturbing and highly sensitive. The behavior of a Ti-indiffused LiNbO3 modulator/sensor has previously been reported.1,2 The device is a channel waveguide Mach-Zehnder interferometer where a difference in arm lengths, δL, gives rise to an intrinsic phase bias ϕo = kneff δL. For optimum linearity ϕo = 90°, which corresponds to δL = 152 nm at the operating wavelength λ = 1.3 μm. The device is formed in X-cut, Y-propagating LiNbO3 in order to both avoid pyroelectric effects causing temperature instability3 and also obtain good voltage sensitivity.
Low noise flip-chip integrated photoreceiver with an InGaAs-PIN photodiode and a GaAs IC
Authors: Horimatsu T. , Oikawa Y. , Makiuchi M. , Sasaki M.
Published: February 2023

Very small input capacitance and high transconductance of the first stage transistor in optical front-end receiver circuit are required to minimize the circuit noise for high bit-rate operation. However, even if bare-chip-assembling is adopted, the excess capacitance due to chip assembly degrades the receiver performance. To minimize the total input capacitance of the receiver circuit, an optoelectronic integrated circuit (OEIC) has been studied for use in the 1.3 ~ 1. 5 μm wavelength range (1) (2), but the integration scale of electronic devices and the material selectivity are limited by the difficulty of the chip fabrication process in InP based OEICs. In this paper, we describe the low-noise and high-speed performance of the flip-chip integrated (3) photoreceiver which consists of an InGaAs-PIN photodiode with very small capacitance and a GaAs pre-amplifier IC, and show the great potentials for long-wavelength optical transmission systems.
Polarization independent LiNbO3 switch with reduced fabrication tolerances employing Δβ and Δκ modulation
Authors: Granestrand P , Thylen L , Stoltz B
Published: February 2023

Polarization independent devices are important in many applications of integrated optics since they make possible a simple interfacing to conventional fibers. However, these devices generally require higher voltages (roughly a factor of 3 to 10 compared to a polarization dependent device); a lower factor in general involves severe fabrication tolerances1,2,3,4,5); when these tolerances are reduced to those of the ordinary stepped Δβ device, this factor tends to increase6). The higher voltage length product of polarization independent devices implies restrictions on the level of integration, and the speed of device operation. Even so, these devices have important applications in local area networks, signal distribution systems, bus systems etc. Below we report a novel type of polarization independent integrated optics switch, which combines modest fabrication tolerances with a drive voltage which is only a factor of 5 greater than a conventional switch. These features, which are obtained by a combination of Δβ and Δκ modulation make the switch amenable to integration.
Polarization Characteristics of MOCVD Grown GaAs/GaAlAs CBH Surface Emitting Lasers
Authors: Shimizu M. , Koyama F. , Iga K.
Published: February 2023

A vertical cavity surface emitting (SE) laser is promising for laser disks and lightwave communications because of its characteristics of narrow circular beam, single-mode operation and so on. For polarization sensitive applications such as magneto-optic disks and coherent detection, the polarization state of lasers must be well defined. The polarization characteristic of SE laser was found to be linearly polarized in another experiment [1],[2], but detailed characteristics such as its direction have not been studied. In this study, the polarization characteristic of MOCVD grown CBH SE lasers was measured and found to be linear along the crystal direction. Also, we discuss the selectivity of the polarization state.
Nonlinear Guided-Wave Device Characteristics
Authors: Stegeman G.I. , Seaton C.T. , Wright E.M. , Finlayson N. , Zanoni R.
Published: February 2023

Many integrated optics devices, such as directional couplers and Mach-Zehnder interferometers, have been developed for switching applications. Such devices rely on either wavevector matching or interference between two guided-wave modes. Typically the output states are controlled electrically by electro-optical tuning of the effective index of one or both waveguide modes. The effective index of an optical waveguide also depends on the guided-wave optical power when one or more of the waveguiding media exhibits an intensity-dependent refractive index. Therefore the operating characteristics of virtually every guided wave device can be controlled by the guided-wave power at the input ports.1
The Nonlinear Asymmetric Mach Zehnder Interferometer in GaAs/AIGaAs
Authors: O'Neill M. , Bell J. , Bhumbra B. S. , Cullen T. J. , Ironside C. N. , Mikami O.
Published: February 2023

We describe the operation of an all-optical switching device based upon an asymmetric Mach-Zehnder Interferometer. Device fabrication techniques in GaAS/AlGaAs materials are summarised. The switching characteristics of the device are analysed using the nonlinear beam-propagation method.
Lithium Niobate Band Pass Response Microwave Modulator With Phase Reversal Electrodes
Authors: Hiser S.C. , Burns W.K. , Bulmer C.H. , Esman R.D. , Moeller R.P. , Djupsjobacka A. , Thylen L.
Published: February 2023

External modulation is advantageous in digital large signal1 as well as in small signal modulation applications. The effects of the dynamics of direct modulation (chirping, patterning) are avoided (of specific significance in digital applications which require large extinction ratios) and the basic bandwidth limiting factors of the direct modulation process (gain coefficient, photon density and lifetime) are replaced by modulator parameters such as "walk off" (difference in optical and microwave velocities) and microwave attenuation in traveling wave type modulators. A further factor of importance in microwave applications is that the high speed modulator and the laser can be optimized separately for high speed and high output power, respectively, such that increased modulated optical power can be achieved with unchanged microwave power. In LiNbO3 baseband traveling wave modulators, the difference in propagation velocities of the optical signal and the microwave signal sets a limit to the bandwidth. However, microwave applications do not require baseband response and generally only require small signal modulation. A number of techniques have been devised to circumvent the walk off problem; closer matching of the propagation velocities2, and different velocity mismatch compensation schemes3, 4, 5, 6. Baseband, bandpass or periodic frequency responses are obtained, with improved figures of merit. We report here a bandpass response modulator based on a two section phase reversal electrode scheme, and compare its performance as a small signal microwave modulator to a conventional baseband modulator.
Picosecond Optical Sampling with LiNbO3 Waveguide and Compressed Laser Diode Pulses
Authors: Yamabayashi Y. , Takada A. , Saruwatari M.
Published: February 2023

Several-tens giga bit digital optical transmission systems would require ultrafast waveform measurements of light pulses with a time resolution of less than ten picoseconds. The optical sampling technique(1,2) utilizing ultrashort laser diode pulses offers an attractive method that avoids problems associated with high-speed electronics. Recently, gain-switched, pulse-compressed distributed-feedback-laser diodes (DFB-LDs) have been used to achieve a time resolution of 8.7 ps(1), where a bulk crystal of LiIO3 was used as an optical sum-frequency generator. This paper reports the first observation of a 25 Gbit/s word pattern with a time resolution of less than 9 ps utilizing a LiNbO3 waveguide, where the sum-frequency signal is emitted as the "Cherenkov radiation" mode. This waveguide approach has two advantages of high conversion efficiency and wide matching bandwidth.
Guided-Wave Polymeric Electro-Optic Modulators
Authors: Teng C.C. , Haas D.R. , Man H.T. , Yoon H.N.
Published: February 2023

Organic materials have shown promise as second order nonlinear materials1; however, device demonstrations have been lacking. This has been largely due to the difficulty of growing noncentrosymmetric crystals out of the polar organic molecules and lack of suitable waveguide fabrication techniques for these materials. We have approached this problem by using polymers where the nonlinear (NLO) moiety is attached to a polymer backbone as a pendant side chain2. Using the polymeric materials, we have fabricated and tested planar waveguide modulators. Linear waveguides have also been fabricated with these polymers and are being developed into phase and polarization rotation modulators.
Generation of Crafted Optical Pulses for Nonlinear Laser Spectroscopy and Propagation Experiments using Electrooptic Time Domain Filtering
Authors: Haner M. , Warren W.S.
Published: February 2023

In coherent atomic and molecular laser spectroscopy, the capability to synthesize a temporally shaped laser pulse is a valuable asset. Experimental and theoretical work on pulse shaping in coherent spectroscopy has shown that precise control over the radiation field can enhance direct and multiphoton excitation or selectively excite an electronic or high vibrational state in a molecular system[1]. Complicated phase and amplitude modulated pulse shapes, such as [sech(at) ](1+3i), have been shown to be insensitive to inhomogeneous broadening, and do not undergo severe distortion due to optical density[2]. In addition to nonlinear laser spectroscopy, pulse shaping technology has been applied to several problems in nonlinear optics. In particular, it has been applied to soliton propagation in fibers where pulse shaping techniques have been used to observe new aspects of optical soliton propagation. Synthesis of tailored pulses with complicated amplitude and phase envelopes has enabled direct observations of complex solitons[3], and of "dark solitons"[4]. Both soliton families have detailed temporal and phase envelopes which can only be generated using pulse shaping techniques. Application of pulse shaping in other nonlinear propagation studies allow one to measure the sensitivity of the nonlinear interaction to phase and amplitude characteristics of the pulse.
Wave-Guide Optical Deflector for Optical Disc Tracking Actuator Using Surface Acoustic Wave Device
Authors: Arimoto Akira , Muraoka Kouji , Shimano Takeshi , Senda Kazuto , Ishikawa Sachiko
Published: February 2023

Optical discs are widely used in data processing systems as well as products such as compact disc and video disc systems. Now, rapid progress is being achieved in terms of the data capacity and rewritability. However,one of the major unsolved problems today is the slow data transfer and tracking access when compared with those of magnetic disc systems. This is because optical discs employ dual actuators called coarse and fine actuator respectively. Each actuator utilizes mechanical components such as galvano mirrors. These components have a slow response time and take more than 20 ms to become stable, because of vibration. It is difficult to remove the mechanical components from the coarse actuator. However, they can be removed from the fine actuator.
Facet Reflection Independent Oscillation of Semiconductor DFB Lasers Equipped with Gain Coupling Mechanism
Authors: Nakano Yoshiaki , Luo Yi , Tada Kunio
Published: February 2023

By loading periodic loss perturbation into GaAlAs/GaAs distributed feedback lasers, we have realized complete single longitudinal mode oscillation which is scarcely disturbed by cleaved facet reflection. Our coupled mode analysis well explains this empirical results.
Modal Dispersion and Attenuation Measurements of Silicon Nitride and Silicon Oxynitride Waveguides using a Streak Camera
Authors: May P. , Basu S. , Chiu G. , Arjavalingam G.
Published: February 2023

It is difficult to make accurate measurements of the intrinsic attenuation of optical waveguides. Most methods rely either on monitoring the input and output powers to the waveguide and making some assumption of the coupling losses /1/ or alternatively measuring the scattering losses as a function of distance along the waveguide /2/, and trying to ensure that the collection efficiency of the measuring system remains constant at the different measurement points. For waveguides of low attenuation the difficulties inherent in these techniques are compounded by having to account for reflection at the end of the waveguides. A short pulse travelling in a waveguide undergoes attenuation and intermodal and intramodal dispersion. In the method described in this paper, the data on attenuation and dispersion of optical waveguides on silicon are obtained from a measurement of the short pulse characteristics using a synchroscan streak camera of 10 ps temporal resolution.
A Novel Integrated Acoustooptic Frequency Shifter
Authors: Tsai C.S. , Cheng Z.Y.
Published: February 2023

Guided-light sources with electronically tunable frequency shift or offset are needed as local oscillators in heterodyne integrated-and fiber-optic communication and sensor systems [1], [2]. A number of schemes for producing such frequency-shifted light sources have been reported [3-16]. One of the attractive schemes utilizes guided-wave acoustooptic (AO) Bragg diffraction [9] in which the frequency of the diffracted light is shifted from that of the incident light by the acoustic frequency. One of the unique features of this AO scheme is its inherent single-sideband property. We had earlier performed AO frequency shifting experiments using the surface acoustic waves (SAW) in planar-, crossed channel-, and spherical-waveguides in LiNbO3 [9-11, 15, 16]. However, the specific device structures utilized all suffer from an undesirable characteristic in that the propagation direction of the frequency-shifted light varies with the frequency of the acoustic wave. This undesirable characteristic will be especially acute in a single-mode fiber optic system in which the very small cross-section of the fiber core is fixed in space, as it will severely limit the useful bandwidth of frequency shift.
InP-based Carrier Injection Optical Switch Array
Authors: Ishida Koji , Inoue Hiroaki
Published: February 2023

An optical switch array is a very important photonic component for future optical information systems. Several non-blocking 4x4 optical switching arrays made of LiNbO3 have been reported1-3). These electrooptic devices exhibit relatively low crosstalk and low insertion loss. However, their drawbacks include device length larger than 60 mm, strong polarization dependence and inability to monolithically integrate other active devices such as semiconductor lasers and detectors. It is well known that the carrier injection into a semiconductor induces a large polarization independent refractive index change. We have been studying InP based optical switch arrays which operation relies on such an effect.4,5) The results obtained so far will be summarized during the talk. Here, we are presenting only our latest results.6)
Integrated Balanced Mixer Circuit for Coherent Lightwave Receivers
Authors: Chandrasekhar S. , Campbell J. C. , Storz F. G. , Dentai A. G. , Joyner C. H. , Qua G. J.
Published: February 2023

The potential for high-density wavelength division multiplexing and very high receiver sensitivity has stimulated research on coherent optical communication techniques [1]. One consideration in the design of coherent receivers is the inherent problem of noise generated by the local oscillator. It has been shown that the local oscillator excess intensity noise can be suppressed by using a dual-photodetector, balanced optical receiver [2]. Initial implementations of this circuit utilized discrete photodiodes and an optical fiber directional coupler [3]. Recently, improved performance has been achieved with integrated twin InGaAs p-i-n photodiodes [4]. In this paper, we report, for the first time, integration of a 3-dB directional coupler with two InGaAs p-i-n photodiodes in a balanced mixer configuration.
Dependence of Chirp on the Number of Quantum Wells in GaAs/AlGaAs Waveguide Modulators
Authors: Hausken T. , Lee K.W. , Simes R. J. , Yan R. H. , Coldren L. A.
Published: February 2023

The optimum number of quantum wells in a phase/absorption modulator or a laser device depends upon the device design, where more wells and the corresponding larger confinement factor can be offset by other factors. Strong tunable quantum size effects have been predicted and observed in waveguide phase and absorption modulators[1-3], and studied as a function of wavelength and voltage near the band edge[4-5] but the optimum number of wells remains uncertain. At one extreme would be a device with no quantum wells at all and using the bulk linear electro-optic (LEO) effect, which would exhibit a chirp parameter nearly infinite (ideal phase modulation). At the other extreme would be a device filled with wells where quantum effects would dominate and the chirp parameter can be <<1 (ideal absorption modulation). An optimum number of wells for a device integrated with a laser may be between these extremes, where the chirp parameter is >10 and there are enough wells to provide a strong effect but not too many to prevent lasing in the active section. This paper compares experimental results to expected values for three structures each with different numbers of wells and compares the advantages of each case.
Low-loss Multiple Quantum Well InGaAs/InP Optical Waveguides
Authors: Deri R. J. , Kapon E. , Bhat R. , Seto M.
Published: February 2023

Semiconductor optical waveguides with low propagation loss are essential for integrating guided-wave optical components with other optoelectronic devices. Realization of such low-loss waveguides on InP substrates is of particular importance to optoelectronic circuits for fiber optic communications in the 1.3-1.5 μm wavelength range, for integration with lattice-matched lasers and detectors. While recent progress has resulted in several reports of low-loss waveguides on GaAs substrates, with losses as low as 0.15 dB/cm,1 there have been few reports of InP-based guides with losses below 1 dB/cm. Losses as low as 0.4±0.1 dB/cm have been reported for double-heterostructure waveguides with InGaAsP guiding layers;2,3 however, structures with a multiple quantum well (MQW) guiding region, which are especially useful for optical signal processing, have exhibited losses twice as large (0.8 dB/cm).4 These loss values refer to the lowest loss waveguides achieved, and were obtained with a small (≤ 10) number of guides. While the lowest achievable loss is an important measure of the quality of crystal growth and guide fabrication, the ability to maintain low-losses over a large area is also of concern for the fabrication of numerous complex guided-wave circuits. In this paper we report MQW waveguides on InP with losses as low as 0.24 dB/cm, significantly lower than previouly achieved losses, and demonstrate that loss ≤ 0.6 dB/cm can be maintained over an appreciable chip area. Our results show that the large number of heteroepitaxial interfaces in MQW guides do not degrade their optical performance.
Passive Intersecting Waveguides from Single Heterostructure and Multiple Quantum Wells of GaAs/AlxGa1-xAs
Authors: Lee T.C. , Mohapatra S.K. , Nagashima M.
Published: February 2023

Active and passive intersecting waveguides can be used as TE-TM mode splitters, wavelength selective devices, electro-optic switches and modulators, interferometric sensors etc. Because of the topological simplicity, e.g reduced number of S-bends, these are promising for high levels of integration. A 4x4 completely non-blocking switch array based on intersecting waveguide approach has been fabricated on LiNbO3:TiO). In this paper, we report the preliminary experimental results on mode, loss and cross-talk characteristics of passive intersecting waveguides fabricated from single heterostructure (SH) and multiple-quantum-well (MQW) double hetero-structures of GaAs/AlxGa1-xAs.
Bragg Gratings on InGaAsP/InP Waveguides as Polarization Independent Optical Filters
Authors: Cremer C. , Heise G. , März R. , Schienle M. , Schulte-Roth G. , Unzeitig H.
Published: February 2023

In fibre-optical transmission systems, operation in the wavelength-division multiplex (WDM) mode allows superior utilization of the transmission capacity of optical fibres. Existing implementations are usually based on hybrid wavelength-selective components /1/. Future optical fibre communication systems require WDM devices which are compatible with the technologies of integrated optics. Devices based on the InGaAsP/InP material system offer the possibility of further monolithic integration with lasers and photodetectors operating in the wavelength range between 1 μm and 1.6 μm /2-4/. This work deals with the fabrication of Bragg gratings on different types of InGaAsP/InP waveguides and with the experimental investigation of their suitability as narrow band optical filters for wavelength division multiplexing systems with small (<10nm) channel spacing.
Integrated-Optical Mode Converter/Frequency Shifter in Ti:LiTaO3
Authors: Howerton P.H. , Burns W.K. , Moeller R.P.
Published: February 2023

A guided-wave frequency shifter is of current interest for use in interferometric sensors such as the phase-nulling fiber-optic gyroscope. It possesses distinct advantages over bulk acousto-optic Bragg frequency Shifters for use in guided-wave systems. These advantages include: high conversion efficiency, high optical carrier suppression, and low insertion loss. Heismann and Ulrich1,2 have reported a col linear electro-optic, Bragg-type frequency shifter in a single mode LiNbO3 stripe waveguide. The device operates by having a TE input mode with angular frequency ω Bragg scatter from a collinear electro-optically induced traveling wave with angular frequency Ω into a TM output mode having angular frequency ω+Ω or ω-Ω. Eknoyan, et al.,3 have extended this concept by fabricating a similar device in LiTaO3 which achieved an order of magnitude increase in optical bandwidth. However, due to fringing fields, that device did not operate efficiently as a frequency shifter.
Automation in Optics Manufacturing
Authors: Pollicove Harvey M.
Published: February 2023

Automated systems based on computer integrated manufacturing (CIM) and flexible machining systems (FMS) have been widely implemented by American industry. Competitive pressures and increasing customer quality demands have motivated application of CIM and FMS concepts over a wide range of manufacturing processes in the electronics and machining industries. This paper describes the CIM-based optical manufacturing technology being developed at the Center for Optics Manufacturing. The Center was established through the joint efforts of the American Precision Optics Manufacturers Association (APOMA), several academic institutions and the Department of Defense.
A New Approach to the Simulation of Optical Manufacturing Processes
Authors: Oinen Don
Published: February 2023

Current methods for generating optical tolerances rely on approximations and a variety of statistical techniques to derive a set of tolerances. Most deal in a simplified fashion with the combined effects of the many parameters that must be controlled during manufacture.
Ways that designers and fabricators can help each other
Authors: Willey Ronald R.
Published: February 2023

There are are variety of things which the designer can do to help the fabricator of his designs if he is familiar with the fabrication processes available. We will give some examples. The designer can let the shop know that the overall thickness of a cemented doublet may be critical to performance, but the thickness of the individual components could be off the nominal by quite a bit and still perform if selected in pairs to meet the overall thickness. Lenses with nearly the same curvature on both sides may end up assembled backwards. Sometimes the designer can adjust the design to make the element fully symmetric to avoid the problem. Often whole lens assemblies can be designed to be symmetric such as the classical Double Gauss objective. This cuts in half the types of components to be tooled and fabricated. The designer can often add some thickness to a lens to reduce its flexibility so that the surface figure can be better maintained during fabrication. When cemented doublets must have tight wedge requirements, the designer can allow the components a relaxed tolerance if one lens is intentionally smaller in diameter than the other. This allows the smaller lens to be moved until it compensates the errors of the wedge in the larger lens.
Simultaneous Alignment and Multiple Surface Figure Testing of Optical System Components via Wavefront Aberration Measurement and Reverse Optimization
Authors: Lundgren Mark A. , Wolfe William L.
Published: February 2023

Component alignment and testing are critical to the final performance of any optical system. Methods of computer aided alignment to improve optical system performance have been gaining increasing attention from investigators.1,2,3By using wavefront aberration measurements in several fields and applying the method of reverse optimization4, perturbing a computer model of the ideal optical system to match the imperfect real system, it is possible to not only calculate the misalignments of the system components but to also measure errors in the surface figures. This makes it possible to perform surface figure tests on components that may be too expensive or difficult to test interferometrically by themselves, and allows computer-aided alignment to be performed on systems for which the exact surface figure of the components may be unknown, making modelling difficult.
Diffraction Performance Calculations in Lens Design
Authors: Malacara Daniel
Published: February 2023

The wavefront deformation may be calculated in two different manners, one is by computing the optical path difference for the rays while computing the spot diagram. The other is by obtaining the wavefront from integration of the transverse aberrations. Both of these methods have their own limitations and advantages.
Fat Rays: A Synthesis of Physical and Geometrical Optics with Gaussian Beamlets
Authors: Greynolds Alan W.
Published: February 2023

Optical systems are primarily designed and analyzed by tracing bundles of rays. These rays are actually discrete points on the geometrical wavefront propagating through the system. The local field amplitude is inversely proportional to the radius of curvature of the wavefront or the distance from a neighboring ray point. Since by definition diffraction effects are excluded from geometrical optics, the energy density is infinite at focus or, in general, on a caustic. These singularities can be removed if the rays are expanded into physical-optics beamlets which are solutions to at least the reduced (paraxial or parabolic) wave equation. The individual fields would then be finite and continuous everywhere, and their superposition would represent the cumulative effects of aberrations, interference, obscurations, and diffraction in the system. This "fattening" of the infinitesimal geometrical rays is analogous to "thinning" the infinite plane waves used in the Fourier transform solutions of physical optics.
Achromatized hybrid diffractive lens systems
Authors: Londoño Carmiña , Clark Peter P.
Published: February 2023

We have investigated the design of broadband hybrid diffractive-refractive lens systems for simple camera systems. When achromatizing one of these systems one typically considers only one diffracted order, assuming 100% efficiency. Kinoform structures can approach 100% efficiency at one wavelength, but it inevitably decreases for other wavelengths. Therefore one must take into account this effect when evaluating image quality.
The Existence of Local Minima in Lens Design
Authors: Kidger Michael , Leamy Paul
Published: February 2023

Since optical design software became widely available in the mid-1960s, there has been discussion concerning the existence of local minima in lens design. Kidger (1) discussed this topic at the Rochester Conference on Lens Design with Large Computers in 1966, and more recently Shafer (2) and O'Shea and Sturlesi (3,4) have discussed the presence of multiple solutions for the relatively simple case of the triplet.
Developments in MTF and Athermal Optimization
Authors: Benham Paul , Kidger Michael
Published: February 2023

At present there is considerable interest in the application of multi-configuration optimization methods to systems which are not simple zoom lenses or scanning systems. In particular, the ability to carry out an optimization in which different configurations represent different temperatures is extremely useful and we will discuss in detail how this can be achieved.
The Role of Aspherics in Zoom Lens Design
Authors: Betensky Ellis
Published: February 2023

Zoom lenses are slowly dominating the field of general purpose imaging, and for such diverse applications as office copiers and 35 mm cinematography they are now considered of equal quality to fixed focal length lenses. For some applications, such as consumer video, fixed focal length lenses now are either rare or non-existent. Until only a few years ago aspherical surfaces could be found in only a few isolated zoom lens designs, but now a large percentage of the lenses being designed for consumer video and compact 35 millimeter, use aspherical surfaces. We undertake here to describe the function these surfaces serve.
Principles of Optimization in Lens Design developped at the Institute of Optics in Berlin (West)
Authors: Kross J.
Published: February 2023

We describe the various principles used in our optimization programs which are applied in a more consequent manner than it is done in other known programs. The iterative optimization process in lens design consists of two main parts: The use of the so called Linear Model and the dynamic adaption to the actual conditions. Corresponding to that the paper is built up.
Quadric Surfaces: Some Derivations and Applications
Authors: Larkin Eric W.
Published: February 2023

Quadric surfaces are described by a second-order equation in Cartesian coordinates. This equation generates 17 unique surfaces, which include as special cases the common conicoid aspheres used in optical design: spheres, ellipsoids, paraboloids, and hyperboloids.
A small-computer program for optical design and analysis, written in 'C'
Authors: Beckmann Leo H.J.F.
Published: February 2023

A modular computer program for the design and analysis of optical systems on a small computer has been developed under the name "Opdesign". While the origins date back into the late seventies and the use of BASIC on, successively, programmable calculators and 8-bit home computers, the current program is written in 'C' and runs on different types of personal computers. Concurrently, the speed of calculations, in particular a skew-ray tracing, went up from one ray surface per second to 30..60 ray surfaces per second depending on the compiler and the hardware. With a program size (executable code) in excess of 250 kByte, the package covers system data (input, general properties), aberration calculation (third order-, wavefront-, exact ray aberrations), a number of tools for design manipulations, and automatic design improvement (by damped least squares method).
Designs of Two-Glass Apochromats and Superachromats
Authors: Mercado R.I.
Published: February 2023

In an earlier paper1, simple criteria for color correction were derived from the dispersion formulas of Hartmann, Cauchy, Schmidt, Conrady and Buchdahl. These criteria were used to develop a simple method for selecting pairs of optical materials that are suitable for designing lens systems that are color corrected for at least three wavelengths in the spectral band of applications. We have been successful in using the glass combinations selected and identified by this method in the design of color corrected optical systems, which include catadioptric and prism systems as well. Earlier applications of these suitable glass pairs were confined to the design of apochromatic and superachromatic low aperture doublets, multiplets, and moderate aperture objectives of the Petzval types.
Design of two- and three-element diffractive telescopes
Authors: Buralli Dale A. , Morris G. Michael
Published: February 2023

For monochromatic applications (e.g., imaging of objects illuminated by laser light), diffractive imaging systems provide an alternative to conventional refractive/reflective systems. In particular, a telescope may be used as an afocal attachment to an existing FLIR-type system to increase entrance pupil size and angular resolution in an application where only monochromatic imaging is necessary. In this paper, we investigate the use of simple two- and three-element diffractive designs for this purpose.
Optical Design of Dual-combiner Head-up Displays
Authors: Kirkham Anthony J
Published: February 2023

A head-up display ('HUD') projects collimated flight information "head up" to the pilot, being superimposed upon the outside world scene by means of a partially reflective 'combiner' glass. The lens design form is invariably a field-flattened Petzval type, working at an aperture ratio between F/0.9 and F/1.4. Fields of view are typically 25 degrees (total), with an instantaneous field of view ('IFOV') around 16° azimuth by 10° elevation. The IFOV is limited by the finite size of the optics.
Design of Reflective Relay for Soft X-ray Lithography
Authors: Rodgers J. Michael , Jewell Tanya E.
Published: February 2023

Optical lithography has demonstrated a resolution capability of about 0.35 micron. Systems using deep-ultraviolet light sources (e.g., excimer lasers) are anticipated to be able to resolve 0.25 micron features. For optical/UV sources, however, the resolution limit appears to be in the range of 0.15-0.25 microns, due to the upper limit of 1.0 on numerical aperture. One way to resolve smaller features, e.g. 0.1 micron, is to use soft x-ray sources. With such a source (with a wavelength, for example, of 13 nm), an optical system with a modest numerical aperture (e.g., 0.08) can be designed to provide resolution significantly better than is possible with optical/UV sources. An optical design which could be used in the formation of images over a 10x10 mm format in the soft x-ray spectral band is described in this paper.
Optical Design and Fabrication of an Infrared Conformal Window
Authors: Spencer Harvey M.
Published: February 2023

The growing need to incorporate Forward Looking Infrared (FLIR) optical systems in high speed aircraft has brought with it the aerodynamic requirement for zero power windows which are conformal with the sensor mounting pod. Such asymmetric, dome-like optical elements must have the same diffraction limited performance capabilities as their predecessor symmetric dome counterparts if the performance of the FLIR used with them is not to be compromised. When of large diameter and used considerably off-axis, the optical design and opto-mechanical considerations become significant and challenging for both the optical designer and the component fabricator.
Knowledge Based Optical Systems Design
Authors: Johnson R. Barry
Published: February 2023

The utilization of artificial intelligence technology in optical system design and its utility as an optical design associate will discussed.
Problem solving of optical design by R graph with Bidirectional search mechanics
Authors: Chang Rong-Seng , Chen Der-Chin
Published: February 2023

Here we are going to discuss how to solving the 1st order optical design problem in analytical and symbolic form and how to communication with computer friencly by artificial intelligent techniques such as Expert system, nature language etc.