bluuebunny/crossref_metadata_2025 huggingface dataset:
Chirped fibre gratings for temperature-independent strain sensing
Authors: Xu M.G. , Dong L. , Reekie L. , Tucknott J.A. , Cruz J.L.
Published: February 2023

Fibre Bragg grating sensors are of considerable interest for a number of sensing applications [1-6]. More recently, chirped Bragg gratings are attracting research interest for strain sensing [2,3]. However, undesirable temperature sensitivity of the fibre grating sensor may complicate its use as a strain gauge. Morey et. al. have suggested that the temperature can be measured and compensated for using a second grating element contained within a different material and placed in series with the first grating [4]. We have also demonstrated that the problem can be resolved by arranging for the simultaneous measurement of strain and temperature [5], or by arranging for the thermal response to be cancelled [6]. Nevertheless, all of the above methods are difficult to implement when a large number of fibre gratings are involved in a multiplexed sensing system. In this paper we describe a novel temperature-independent strain sensor based on the use of a chirped fibre grating in a tapered optical fibre.
Wavelength Shifts in Fiber Bragg Gratings due to Changes in the Cladding Properties
Authors: Meltz G. , Morey W.W. , Hewlett S. J. , Love J. D.
Published: February 2023

Fiber Bragg grating (FBG) devices have received wide attention because they are useful in a variety of passive and active WDM network components and for sensing various measurands. These applications take advantage of either the broad- or narrow-band spectral characteristics of the Bragg resonance and its sensitivity to extrinsic perturbations. In this paper, we examine FBG tuning by controlling the effective index of the optical waveguide through modification of the cladding. This causes a change in the evanescent field which is reflected in a proportional shift in the Bragg wavelength. If the change is large enough then it can be detected by measuring the shift in the resonance line or equivalently by determing phase-path imbalances in an auxiliary interferometer. Very small wavelength changes are more easily measured by forming a compound FBG transmission filter, such as a three-grating Fabry-Perot interferometer, and using a tuneable laser to determine the transmission or reflection spectrum.
Fiber grating filters based on radiation- and cladding-mode coupling
Authors: Erdogan T. , Sipe J. E.
Published: February 2023

Fiber Bragg gratings formed in germanosilicate optical fibers by ultraviolet (uv) irradiation [1] have developed rapidly in recent years. Numerous applications have been demonstrated that utilize fiber gratings as mirrors, in which a forward-propagating bound mode couples to a backward-propagating bound mode of the same type, and as mode converters, in which one type of bound mode couples to a different type. Fiber gratings can also function as effective loss filters by enabling the coupling of a bound mode to the radiation modes of the fiber [2]. Such filters have been demonstrated as spectrally selective loss elements for flattening the gain spectrum of an erbium-doped fiber amplifier [3]. Other potential applications of these filters for optical communications include filtering of amplified spontaneous emission (ASE) in optically amplified systems, and spectral clean-up filtering in wavelength-division multiplexed (WDM) systems. Furthermore, grating filters are desirable components for numerous other fiber-optic systems, such as fiber lasers and distributed sensor systems. The main advantages provided by fiber-grating filters for these applications include: low insertion loss, high spectral bandwidth, low back reflection, and potentially low cost.
Chirp, Self-Chirp and Meta-Chirp in Sampled Fibre Gratings
Authors: Ouellette François , Eggleton Benjamin J. , Hill Peter C. , Krug Peter A.
Published: February 2023

Sampled Bragg gratings consist of a periodic modulation of the amplitude and/or the phase of the Bragg grating. In the frequency domain, their reflectivity spectrum shows a number of equally spaced peaks, covering a range of wavelengths determined by the Fourier contents of the modulation, or "sampling" function. Sampled gratings have been used in DBR semiconductor lasers to extend their tuning range [1].
Optical dark soliton generation using a fibre Bragg grating
Authors: Kashyap R , de Lathouwer M , Emplit Ph , Haelterman M , Campbell R J , Armes D J
Published: February 2023

There is currently worldwide interest in the theory and transmission of dark solitons for application in communications. Theoretical techniques have been proposed[1-3] for the generation of CW dark soliton pulse trains. One of them has been recently demonstrated recently [4]. The techniques rely on spectral filtering of a train of mode-locked pulses using both conventional phase and amplitude masks[l,5], or on the adiabatic transformation of a beat frequency from two lasers[3,4], A third approach[2] is based on the direct modulation of a CW signal from a DFB laser. In another technique, a chirped fibre grating was used to provide the correct sign of dispersion in a Pr:ZBLAN fibre laser to generate dark pulses[6]. In the spectral filtration technique, the frequency content of mode-locked pulses is first spatially dispersed and this allows for the alteration of the amplitude and phases of the spectral components in the Fourier plane[1]. The Fourier transform of the filtered spectrum generates the dark pulse train. These techniques are generally more suitable for the generation of ultra high repetition rate dark pulse train since it is easier to filter larger bandwidths.
UV- induced stress changes in optical fibers
Authors: Limberger H. G. , Fonjallaz P. Y. , Salathé R. P. , Cochet F.
Published: February 2023

Photosensitivity in optical fibers has first been observed by Hill et al. in 1978.1 Recently, the application of Bragg gratings has considerably been increased due to the introduction of side exposure techniques.2 Index changes of 10-3 have been achieved even in standard telecommunication fibers.3 Reliable fabrication of Bragg gratings depends on the detailed knowledge of the underlying mechanisms of photo-induced index changes. The basis of all proposed mechanisms is the ionization of a GeO deficiency center that exhibits an absorption bands in the UV at 240 nm. A model based on the change of color centers that include 3 or 4 absorption bands,4,5 a stress relaxation model,6-8 and structural changes9,10 have been proposed as origin of photosensitivity. In the color center model the index changes can be calculated from absorption changes using the Kramers-Kronig relationship. Including 4 absorption bands, an index change of 2 × 10-4 has been calculated.5 Higher index changes have been explained using a model based on thermoelastic stress relaxation where the photoelastic effect leads to the index change.6-8 The largest achievable stress and photoelastic index changes would then be determined by the initial thermoelastic stress. Even higher values may be explained by glass densification.9’10 Recently, the core stress in fibers with different Ge concentrations before and after UV irradiation with different doses has been measured.11,12 Such stress measurements allow directly to test the stress relief model and to correlate stress changes with refractive index changes. Here, we report on extended measurements performed on 3 fibers with Ge concentrations of 9%, 12% and 18% and propose a new model to explain the results.
Dynamics of ultraviolet induced luminescence and fiber Bragg grating formation in the high fluence regime
Authors: Svalgaard Mikael
Published: February 2023

Germanosilicate glass exhibits a strong absorption band at 240 nm which can be bleached upon excitation with UV radiation. Simultaneously, a permanent increase of the refractive index at longer wavelengths is seen. Experimental results indicate that the UV absorption band is due to germanium related oxygen deficient centers (GODC's). Excitation and bleaching of these defects triggers a range of not fully understood processes which are responsible for the UV induced index change. Photoluminescence (PL) bands at 290 nm and 400 nm have also been associated with GODC excitation and a correlation between the 400 nm PL dynamics and the dynamics of the index change has been reported 1. Other experiments indicate increased concentrations of Ge-related drawing induced defects (Ge-DID), associated with 650 nm luminscence, following UV irradiation of germanosilicate fiber preforms 2 Recent experiments have shown that UV induced index changes can be strongly non-linear as a function of the exposure time, with several maxima occuring during one UV exposure 3. In this paper we report results indicating that these non-linearities may be associated with a corresponding behavior of the UV induced luminescence.
Measurement of Photo-induced Charge Distribution in Seeded Second Harmonic Generation by Charge-Selective Etching in Glasses
Authors: Kyung Jae H. , Lawandy N.M.
Published: February 2023

Ever since the discovery of efficient second harmonic generation (SHG) in centro symmetric optical fibers [1-4] and bulk glasses [5,6], many researchers, through experimental and theoretical work, have investigated this problem in the hopes of developing models to explain the mechanism behind this unexpected effect. Much of the work focused on the mechanism responsible for producing a quasi-phase matched effective χ(2) in these materials. Models such as the creation of a semi-permanent dc electric field via optical rectification field [7], charge organization by light controlled transport effects [8], and most recently, directional photo-ionization [9] were proposed to explain this phenomenon. Although these models were successful in explaining the mode symmetries of the radiated second harmonic light at high encoding intensity regimes, no one had been successful in directly measuring the charge distribution responsible for second harmonic generation in glasses. Work by Dominic and Feinberg [10] used an SHG mapping technique where they focused a probe beam onto a seeded area of a SK5 glass sample and inferred its charge distribution from the radiated SHG power. Their study supported the dipolar distribution predicted by directional photo-ionization model at high encoding intensities, but did not address the strong mode symmetry violation at low encoding intensities previously reported by Driscoll and Lawandy [11].
Charge Trapping in Metal Ion-Activated Quantum Dot-Doped Silica Glasses
Authors: Huston Alan L. , Justus Brian L.
Published: February 2023

Photosensitive glasses containing metal-ion-activated, quantum dot semiconductors such as ZnS:Cu+ have been developed. Exposure to UV or ionizing radiation (γ-ray) results in the generation of trapped electrons with a trap density of approximately 1018/cm3. The presence of such a high density of trapped charges in a transparent glass suggests a number of possible applications including optical storage and electro-optic modulation.
Photorefractive Beam Coupling in BaTiO3
Authors: Fairchild P. , Davis K. , Valley M.
Published: February 2023

Phase conjugation in photorefractive materials has been shown to be a useful technique for coupling two separate laser input beams(1,2). Recently Eason and Smout(2) have demonstrated that two mutually incoherent beams could be coupled in BaTiO3. We have extended these studies by carrying out beam coupling experiments in BaTiO3 designed specifically to examine phase locking and to investigate the mechanisms responsible. Our results indicate that two beams co-pump one another in a manner similar to that of self pumping for a single input beam (3). When co-pumping occurs the relative phases of the two conjugate returns are locked in phase to better than λ/10. In the co-pumping mechanism each input beam forms one of the two counter–propagating pump beams in the self-generated four wave mixing (FWM) regions. In this way each conjugate has a common phase reference (Figure 1).
Incoherent Beams Sharing Photorefractive Holograms
Authors: Ewbank M.D.
Published: February 2023

Two mutually incoherent extraordinary beams of laser light, incident on opposite a-faces of a BaTiO3 crystal, generate a set of photorefractive holograms that are simultaneously read by both beams and produce a pair of phase-conjugate beams.
Mechanisms for internally self-pumped phase conjugate emission from BaTiO3 crystals
Authors: Gower M C , Hribek P
Published: February 2023

Detailed measurements of the self-pumped phase conjugate emission which arises from internal reflections within crystals of BaTiO3 have been made. Four-wave mixing, possibly enhanced by stimulated photorefractive scattering around loops of light internally generated within the crystal as well as four-wave mixing at coupling regions of a ring cavity set up between diagonal corners of the crystal are two mechanisms which are believed to give rise to phase conjugate beams. An explanation is also given for the unstable effects often observed on the phase conjugate beam and which gives rise to frequency shifts, pulsations and oscillations. The power of the beam incident upon the crystal determines the threshold characteristics for self-pumped phase conjugate emission.
New Perspectives on Multiple Wave Mixing in Kerr-Like and Photorefractive Semiconductors—Theory and Experiments
Authors: Khoo I. C. , Liu T. H. , Michael R. R.
Published: February 2023

We present new fundamental theoretical aspects and experimental verifications of optical multiwave mixings (diffractions and beam amplifications) in a Kerr-like medium that may also possess photorefractivity, and the interplay between various input and generated beams, the optical nonlinearity and geometrical-physical-optical parameters, nonlocality and frequency offsets, etc., in semiconductors (Si, GaAs).
Nanosecond response and "coasting" in photorefractive barium titanate
Authors: Mahgerefteh Daniel , Feinberg Jack
Published: February 2023

A variety of nonlinear optical devices and effects have been demonstrated in photorefractive crystals of barium titanate, whose speed is known to increase with optical intensity. We present results of experiments to measure the scaling of the response time of barium titanate with optical intensity, with the time response varying over the range of seconds to nanoseconds. We measured the erasure rate of a photorefractive grating in two BaTiO3 samples using either a continuous-wave dye laser or 20-nanosecond pulses from an excimer-pumped dye laser, both at
λ=
579 nm. The erasure efficiency was found to vary linearly with intensity I in one sample and as I0.86 in the other, using optical intensities as small as 10-4 Watts/cm2 and as large as 10+5 Watts/cm2. An unexpected result is that in both BaTiO3 samples the erasure efficiency with the pulsed laser decreased by ∼30% as the optical pulse rate was increased from 0.1 Hz to 15 Hz, and remained constant for higher repetition rates, up to the maximum of 50 Hz. We also observe that, after partially erasing a grating with a millisecond duration pulse from a low-power continuous-wave argon laser, erasure of the photorefractive grating continued for ∼100 msec after the optical pulse ended. We believe that this "coasting" of grating erasure is responsible for the dependence of the grating erasing efficiency on the repetition rate of the high-intensity pulsed laser, as described above. We present a simple band model to explain our experimental results. This model includes shallow traps and also the contributions of both electrons and holes to the formation of the photorefractive grating. We also discuss how "coasting" affects grating formation when using nanosecond optical pulses.
Analysis of energy transfer in semi-insulating Inp:Fe generated by nanosecond light pulses
Authors: Fabre J.C. , Jonathan J.M.C. , Roosen G.
Published: February 2023

Research in photorefractive materials is mainly fostered by the potential for performing a large number of parallel operations for computing applications.
Optical Tracking Filter via Transient Energy Coupling Effect
Authors: Kwong Norman S.-K.
Published: February 2023

Recently there are extensive studies conducted on the phenomenon of steady state two-beam coupling in photorefractive media with the induced index grating π/2 phase shifted from the light interference pattern. However very little attention is paid to the transient energy coupling (TEC) effect in "unshifted" holographic media, such as photorefractive crystal operating in the 'charge drifting' mechanism, and some χ(3) media, etc.. This paper investigates the TEC effect and apply this effect to an optical tracking filter.
Growth and characterization of photorefractive Bi12TiO2Ø (BTO)
Authors: Rytz D. , Klein M.B. , Wechsler B.A. , Schwartz R.N. , Kirby K.W.
Published: February 2023

Bi12TiO2Ø (BTO) is an isomorph of Bi12SiO2Ø (BSO) and Bi12GeO2Ø (BGO). Each material is cubic (point group 23) and exhibits interesting photorefractive properties. BTO, although much less extensively investigated, has several specific advantages, namely its lower optical activity by a factor of 3.5 compared to BSO and BGO [1], its larger electro-optic coefficient [2,3], and its higher sensitivity at 633 nm [4]. In recent years, Petrov and coworkers [4] have demonstrated very high values of beam coupling gain and diffraction efficiency at 633 nm in BTO using anisotropic scattering and the ac-field effect.
High Contrast Photorefractive Two-Wave Mixing in GaAs for Optical Computing Applications
Authors: Partovi Afshin , Garmire Elsa M.
Published: February 2023

Recent results by Partovi, Garmire, and Cheng [1] show that by utilizing the polarization properties of photorefractive beam coupling, a rotation of the polarization of the two writing beams can be observed. By using a polarization analyzer, this photorefractive rotation of polarization can be turned into an amplitude modulation. ON-OFF ratios of better than 6 to 1 have been observed experimentally without application of any external fields. In the normal geometry [2], beam-coupling energy transfer of only 10-20 percent is possible between the two beams due to the small electrooptic coefficient in GaAs. In this paper, we discuss the applications of the photorefractive polarization rotation technique for optical computing. The performance of a device utilizing this method with externally applied electric field will be described at the conference.
Cross-Polarization Two-Beam Coupling in Photorefractive GaAs Crystals
Authors: Yeh Pochi , Cheng Li-Jen
Published: February 2023

We report theoretical and experimental investigations on the cross- polarization coupling of two contra-directional laser beams in a photorefractive GaAs crystal.
Complete All Optical Switching of Visible Picosecond Pulses in Birefringent Fiber
Authors: Rothenberg Joshua E.
Published: February 2023

Switching of visible picosecond pulses with a 50:1 contrast ratio is demonstrated in a time-division interferometry arrangement. The high-contrast switching of the signal is accomplished by uniform cross-phase modulation by an orthogonally polarized control pulse, which walks though the signal during propagation in a strongly birefringent 10 meter fiber.
Nonlinear Loop Mirrors for All Optical Switching
Authors: Blow K. J. , Lucek J. K. , Smith K.
Published: February 2023

Optical fibres have brought an enormous benefit to telecommunications through their very low loss and high bandwidth. At present, these benefits are restricted to point to point transmission, the optical pipe. The next major challenge for optical technology is in the switching domain which is currently performed electrically. In this paper we review the properties of non-linear interferometers used for all optical switching. We also describe our recent experiments demonstrating all-optical clock recovery. The combination of our non-linear fibre switching and clock recovery circuits allows the demonstration of more advanced functions including all-optical signal regeneration and memory.
Fast LD Wavelength Switching with Rapid Stabilizing Control for WDM Network
Authors: Shiozawa Takahiro , Shimosaka Naoki , Fujiwara Masahiko , Shiragaki Tatsuya
Published: February 2023

Recently, requirements have been increasing for large throughput networks for use in asynchronous transfer mode (ATM) cell transfer, for example, subscriber transfer network. In order to meet the requirements, optical networks adopting wavelength-division multiplexing (WDM) technologies, have been studied. The authors have recently proposed a WDM ring optical fiber network. In this paper, a novel control scheme for fast laser diode (LD) wavelength switching with rapid stabilizing is proposed, which is the key technology for the proposed network. Obtained characteristics are suited for 600Mb/s cell speed WDM ring network. The proposed control scheme can be applied to over 10Gb/s cell speed networks.
Optically Implemented Shuffle Equivalent Interconnection Topologies Based on Computer Generated Binary Phase Gratings
Authors: Cloonan T. J. , Richards G. W. , Morrison R. L. , McCormick F. B. , Sasian J. M. , Lentine A. L. , Hinterlong S. J. , Hinton H. S.
Published: February 2023

Novel implementations of nodes and space-invariant holographic interconnections are described. Their effect on laser and optical component requirements within photonic extended generalized shuffle networks is examined.
Holographic Perfect Shuffle Interconnections for Planar Optics
Authors: Song S. H. , Lee E. H. , Carey C. D. , Selviah D. R. , Midwinter J. E.
Published: February 2023

For perfect shuffle interconnections, a planar optical configuration with two double-imaging deflective-reflective holograms is proposed. Interconnection capacity is derived from an aberration analysis.
Optically-processed Self-Routing for 1D and 2D Photonic Switching Architectures
Authors: Prucnal Paul R.
Published: February 2023

In future fiber-optic broadband integrated digital services networks, the large data rates in the fiber-optic transmission links as well as the large number of packets transmitted per second will place severe demands on the required transmission bandwidth and reconfiguration speed of packet switches. Although electronic switching technology has already achieved high switching speeds, it is possible that it will be difficult for electronic switches to match the transmission bandwidths that the fiber-optic links can provide. Thus photonic switches may be needed to provide a transmission bandwidth that matches the aggregate bandwidth of the services carried by the fiber. If packet switching is used, then the reconfiguration speed of the photonic switch must also be fast.
Photonic 2X2 Packet Switch with Input Buffers
Authors: Spring Jonathan , Tucker Rodney S.
Published: February 2023

Packet switching is an integral part of Asynchronous Transfer Mode (ATM) switching systems in Broadband ISDN (B-ISDN) and will have a major input on future photonic communications systems. Self-routing packet switches are the basic switching elements in ATM networks. There have been a number of recent demonstrations of self-routing photonic packet switches, for example [1], [2]. A key feature of these switches is that the information content (payload) of a packet can have a data rate which is not limited by electronics [1].
Advances in SEED based free space switching systems
Authors: Lentine Anthony L.
Published: February 2023

One approach to increase the interconnection bandwidth between electronic integrated circuits is to interconnect these ICs using beams of light imaged on and off each chip using lenses. This technique is often called free space digital optics. The ICs themselves could be very simple, such as an array of NOR gates, or very complex, such as an array of self-routing switching nodes or other processing elements. The SEED technology, which can incorporate detectors and optical modulators along with traditional electronic components, is a leading candidate for these optically interconnected ICs.
Single-Mesa Optical Memory and Logic Pixels for Highly Parallel Arrays
Authors: An Xilin , Keib K. M. , Hafich M. J. , Beyette F. R. , Feld S. A. , Robinson R. Y. , Wilmsen C. W.
Published: February 2023

Optical array processors inherently take advantage of parallelism and show great promise for image/data processing or interconnection networks where electronics has been limited. In order for the optical array processors to compete with electronics, however, they must be ultra-fast (above GHz), highly parallel (> 104 pixels), or moderate in both, depending upon the application. Since an ultra-high frame rate requires careful circuit design and more electronics needs to be in corporated in each pixel, parallelism has to be trade off for speed. Arrays constructed of simple pixels, on the other hand, provide high parallelism with fairly fast speed (1 ~ 100 MHz), which are very suitable for image processing and some other applications.
Monolithic Integration of GaAs/AlGaAs Multiple Quantum Well Modulators and Silicon Metal-Oxide-Semiconductor Transistors
Authors: Goossen K. W , Walker J. A. , Cunningham J. E. , Jan W. Y. , Miller D. A. B. , Tewksbury S. K , Hornak L. A.
Published: February 2023

It is now generally recognized that one likely scenario in which photonics is used in a switching environment is where it is integrated with electronics.1 This concept takes advantage of the greater capacity of electronics for complexity, functionality, and memory, and the greater capacity of photonics for communications. The most concrete realization of this concept is where photonics functions in the role of optical interconnects between electronic integrated circuit chips (ICs). This entails the monolithic integration of some photonic elements (both receiver and transmitter) on the chip. Also, since an attractive feature of optical I/O is that it can occur normal to the surface of the chip, allowing two-dimensional arrays of interconnects to be formed, surface-normal photonic elements should be used.
Ti:LiNbO3 Photonic Switch Modules for large, Strictly Non-blocking Architectures
Authors: Murphy Edmond J. , Richards Gaylord W. , Murphy Timothy O. , Fatehi M. T. , Bergstein Shalom S.
Published: February 2023

The understanding of guided wave switching devices and optical switching system needs has matured such that it is appropriate to consider optimum system architectures and optimum device topology(1,2,3). Here we report switch modules which simultaneously optimize these constraints. We first describe an architecture that deals with the constraints of guided wave photonic switch arrays. Then we discuss the design, fabrication and testing of the switch modules utilized in this architecture.
A resonant III-V semiconductor layer and a grating coupler integrated in a waveguide modulator for far-infrared light
Authors: Stiens J. , De Tandt C. , Ranson W. , Vounckx R. , Veretennicoff I. , Borghs G. , Demeester P.
Published: February 2023

Waveguide and grating structures offer a potential basis for novel far-infrared light (8-12 μm) integrated optics, as well as for replacing existing bulk infrared optical systems with guided-wave alternatives1,2. At these wavelengths residual waveguide losses are expected to be very small. Integration concepts can be applied with relaxed dimensional tolerances at these longer wavelengths. In this paper a new application of a resonant semiconductor layer integrated in a far-infrared waveguide modulator will be explained and experimental backing will be given.
Nonlinear Loop Mirrors for All-Optical Switching
Authors: Blow Keith J.
Published: February 2023

No summary available
A Photonic Time-Division Switching Experiment
Authors: Bergland G. D.
Published: February 2023

An experimental switching system is being designed and built for interconnecting broadband circuits through a photonic time-multiplexed switching network under DFINITY® Communications System call control. The system is called DiSCO, for Distributed Switching with Centralized Optics. The DiSCO system is designed to switch broadband voice, data, and video calls over time multiplexed network paths through a guided-wave photonic network. The photonic network paths are transparent to data and are thus independent of transmitter and receiver bit rate. They are formed by linking together one or more Universal Time-Slots each capable of continuously transporting between 64 Kbps and 3 Mbps of voice, data or video signals. DiSCO's Time-Space-Time system architecture, the photonic broadband switching application, and its Cross-Talk Avoiding switching network topology are well matched with the emerging lithium niobate guided-wave directional coupler and digital optical switch technologies. The DEFINITY System architecture and technology platform is being used and extended in a natural way to implement this experimental system. While this gives the prototype a “production quality” appearance, this should not be taken as an indication that DiSCO will be offered as a commercial product.
Sparsely-Filled Densely-Wavelength-Division-Multiplexed Networks
Authors: Midwinter J E
Published: February 2023

It has been clear for some time that optical fibre transmission systems have the potential to carry vastly greater amounts of traffic than they are currently used for. For example, in Fig.1, we show typical values for the insertion loss of a 50km fibre section in the 1500nm window and overlay it with an approximate representation of an Erbium Doped Fibre Amplifier (EDFA) gain spectrum. The combination promises transparency over a spectral window of about 35nm width, corresponding to a spectral bandwidth of approximately 4700 GHz. Dispersion in the fibre seems likely to limit the data rate transmitted over long distance circuits (say 1000km) to the region of 1Gbit/s unless optical equalisation techniques are employed or special low dispersion (dispersion shifted) fibres are employed. Moreover, it is clear that at the terminations of any long haul system, the signals will be reconverted to electrical form. Two questions have thus presented themselves to us. How can this awesome potential of the fibre be better used and, at the same time, how can such higher capacity signals be routed and distributed through a complex multinode network in a flexible manner without returning them to the electronic domain? This latter question raises key points about how the signals will be multiplexed in the optical domain.
Acousto-Optic Crossbar Photonic Switch
Authors: McLeod Robert , Weverka Robert , Wu Kuang , Wagner Kelvin , Mickelson Alan , Roth Richard
Published: February 2023

We have designed an optical crossbar which utilizes a single bulk acoustooptic device. The theoretical, numerical, and experimental operation of the switch are presented.
High-Contrast Modulation of Asymmetric Fabry-Perot Modulators at 20 GHz
Authors: Barron C. C. , Thibeault B. J. , Mahon C. J. , Coldren L. A.
Published: February 2023

Asymmetric Fabry-Perot modulators (AFPMs) could serve as the optoelectronic link in smart-pixel processor or interconnection systems. We have fabricated AFPMs with the potential of operating at speeds of 30-40 GHz. Here we demonstrate large-signal (high-contrast, low-insertion-loss) modulation of these devices at 20 GHz.
GaAs/AlGaAs FET-SEED Receiver/Transmitters
Authors: Woodward T. K. , Lentine A. L. , Chirovsky L. M. F. , Focht M. W. , Freund J. M. , Guth G. D. , Leibenguth R. E. , Smith L. E. , D’Asaro L. A. , Laskowski E. J. , Pei S. S.
Published: February 2023

Integration of active optical elements (GaAs-based multiple quantum-well pin diode modulators) with semiconductor microelectronics (GaAs-based doped-channel HFETs) is obtained. We discuss the improved sensitivity (less than 100 fJ optical input energies) and higher operation rates (to 650 Mb/s) that result from this combinations. We do so within the context of simple receiver/transmitter-pair circuits containing at most 5 transistors and 6 diodes.
Review of ARPA-sponsored WDM Networking Projects
Authors: Brackett Charles A.
Published: February 2023

The concepts and progress of current ARPA-sponsored WDM networking projects will be reviewed, with emphasis on what has been learned and where new challenges lie.
Dualities among “Space,” “Time” and “Wavelength” in All-Optical Networks*
Authors: Kobayashi Hisashi , Kaminow Ivan P.
Published: February 2023

All-optical networks (AONs) are emerging as the next generation broadband networks for both wide-area and local-area networks. In order to fully exploit the enormous bandwidth that optical channels can provide, it is essential to make the best use of WDM (wavelength division multiplexing), TDM (time division multiplexing) and SDM (space division multiplexing). A device called “wavelength grating router (WGR)” [3, 4] (also known as N × N multiplexer) has been developed to provide interconnections in an AON, allowing wavelengths to be reused in different parts of the network [1]. Figure 1 (a) gives a schematic diagram of the N × N static WGR, in which the number of wavelengths F is equal to the number of ports N. Figure 1 (b) is an equivalent representation of this device in terms of an array of wavelength multiplexers D
w
and that of wavelength multiplexers M
w
[2].
Gigahertz Clock Synchronization using a Nonlinear Optical Loop Mirror as an All-Optical Phase Comparator
Authors: Hall K.L. , Rauschenbach K. A. , Swanson E.A. , Chinn S.R. , Raybon G.
Published: February 2023

High-speed clock recovery or clock synchronization is an important function in realizing future 100 Gb/s time division multiplexed (TDM) communication systems. Optical clock recovery techniques are attractive because they can accommodate bit rates in excess of those allowed by electronics. To date, a number of optical clock recovery and synchronization schemes have been demonstrated including injection-locking diode [1] and fiber [2] lasers. Also, optical phase lock loops have been demonstrated using nonlinear crosscorrelation of two pulse streams as a bit phase sensor. Such schemes have included four wave mixing [3] and gain modulation [4] in diode amplifiers and second harmonic generation in a LiIO3 crystal [5]. In this paper, we demonstrate all-optical bit phase comparison using a nonlinear optical loop mirror. In addition, we show that a harmonically modelocked external cavity laser can be synchronized to a 40 GHz pulse train generated using soliton compression of a Mach-Zehnder modulator output[6].
Photonic Switching of Optical Interconnects in Large Telecom Nodes
Authors: Buhrgard Magnus
Published: February 2023

A large scale introduction of broadband services would put challenging demands on the telecom transport network. The rapid development in optical transmission will most likely meet the demands in this area, whereas the potential bottlenecks are found in the transport network nodes. New technologies are needed to handle the large traffic through the nodes more efficiently.
Photonics Beyond Information Transport?
Authors: Kogelnik Herwig
Published: February 2023

Photonics has rapidly become the dominant technology for the transmission of information in the national and global infrastructure, including undersea, terrestrial long-haul, CATV and local telephone access applications. Expanding this success deeper into the network, we are challenged by new requirements such as conforming to the new ATM (asynchronous transfer-mode) standards and by new opportunities such as wavelength routing and transparent high-capacity networking.
Telecom Networks Going Photonic: Reconciling Transparency with Scalability
Authors: Dumortier Philip , Van Landegem Thierry , Masetti Francesco , Sotom Michel
Published: February 2023

The introduction of Wavelength Division Multiplexing (WDM) techniques into fiber networks opens perspectives for a global transparent optical telecommunication backbone. One of the most promising features of optical telecommunications is to provide a common infrastructure which could become an integration factor in a heterogenous but interconnected network environment. Furthermore optics can provide a degree of network transparency to bitrate, transfer mode and signal format of the transported signals. By using transparent optical crossconnect nodes, based on space and wavelength routing, a rearrangeble network topology can be achieved. Local exchanges could, in principle, be connected directly to each other through end-to-end transparent optical paths.
OFDM cross-connect with an embedded free-space switch
Authors: Kuhlow B. , Teich G. , Walf G.
Published: February 2023

The underlying node model of the cross-connect is sketched in Fig. 1. Eight incoming fibers each supporting 16 densely multiplexed frequencies can be routed arbitrarily to 16 frequencies carried on each of eight outgoing fibers. After power splitting of an incoming OFDM signal, tunable frequency selective receivers select a prescribed OFDM channel using the circuit switched mode. Due to their high selectivity the tunable heterodyne receivers provide the required signal demultiplexing function and in turn a reordering function. Conceptually, switching is performed in the space domain by electrical space switching stages with free-space interconnects between them. The choice of 1.5 μm for the wavelength is suitable for an optical transparent network, where the electronic switches will be replaced by optical switches in a further step of development.
A photonic WDM packet switch with reduced complexity due to wavelength converters
Authors: Danielsen S. L. , Mikkelsen B. , Joergensen C. , Durhuus T. , Stubkjaer K. E.
Published: February 2023

Future broadband networks are expected to utilise WDM and optical switching to increase the network capacity and flexibility [1]-[3]. Furthermore, ATM is selected as standard for future broadband services, hence, optical packet/ATM switches [4,5] for WDM networks are of considerable interest. Of major concern for such all optical switches is the optical buffering as well as the complexity of the space-switch block addressing the optical buffers. We show, that by implementing tuneable optical wavelength converters (TOWC) the number of delay-lines in the buffer can be reduced and thereby also the size of the space-switch block. Based on measured features for semiconductor optical amplifier (SOA) gates that are used to build the space-switch, we predict that a 16x16 switch with 4 or 8 wavelength channels is feasible.
Experimental cascade of four fully reconfigurable all-optical crossconnects with transmission over 1300 km G.652 fiber.
Authors: Jourdan A. , Soulage G. , Dembeck L. , Wünstel K. , Artigaud S. , Da loura J. , Renaud M. , Bachmann M. , Ellenberger G. , Sotom M.
Published: February 2023

The low-penalty experimental cascade of four all-optical crossconnects at 2.5Gbit/s, including transmission over 1304km G.652 fiber is assessed and used for discussion of routing nodes cascadability.
A Computer Designer’s View of Optical Interconnects
Authors: Davidson Howard
Published: February 2023

In the same period time where optical interconnects have assumed a dominant position in long haul telecommunications applications they have made only minor penetration into the computer network marketplace, and no penetration at all into the internal interconnections of computers. I shall describe some of the reasons for this, and some new developments that may encourage the use of optical interconnects within and between computers.
Phase-Insensitive, Ultrafast All-Optical Switch Based on Parametric Down-Conversion
Authors: Kobyakov A. , Torchigin V.P. , Schmidt E. , Lederer F.
Published: February 2023

In a search for all-optical signal processing elements operating at a picosecond time scale nonlinear phenomena in quadratic media, extensively studied since many years in a different context were revisited lately. However, all devices proposed and implemented to date (see [1,2] and Refs, therein) have certain drawbacks complicating their use as all-optical amplifying/switching devices, viz., low amplification because of a strong control signal in intensity-controlled devices, smooth switching characteristics of Mach-Zehnder interferometers, and a requirement of fast phase control in phase-sensitive devices [3]. A key requirement of all devices proposed until now is the coherence of pump and signal beams because the χ(2)-process strongly depends on the relative phase. Here we demonstrate that this phase-insensitive amplification/switching can be achieved by a three wave interaction even with reduced pump power requirements. In what follows we focus on the so-called vectorial or type II SHG where two orthogonally polarized fundamental frequency (FF) components A1 and A2 interact with the only second harmonic (SH) wave B polarized parallel to one of the fundamentals [2].
Nonlinear Silver Quantum-Dot Composites for All-Optical Switching
Authors: Gonella F. , Borsella E. , Mattei G. , Mazzoldi P. , Battaglin G. , Polloni R. , Haglund R. F. , Osborne D. H. , Garrido F.
Published: February 2023

Nonlinear optical materials are essential components of functional photonic devices for optical communications, in particular, all-optical switching devices. Nonlinear switching devices can be based on optical waveguide structures which provide strong beam confinement in prescribed patterns. In these devices, the intensity of an optical signal is used as the parameter that causes switching between two output channels, thus performing logic operations. In the last few years, composite glasses formed by embedding semiconductor or metal nanoclusters in glass have attracted much attention as promising materials in this research area [1]. In particular, metal nanocluster-doped glasses, i. e., glasses which contain crystallites of metals, show an enhanced third-order susceptibility [2], whose real part is related to the intensity-dependent refractive index. The technological interest is strengthened by the general interest in strongly quantum-confined electronic systems which exhibit several effects deriving from the increased electronic density of states near the conduction-band edges. This suggested the introduction for metal nanoclusters-doped composites of the term metal quantum-dot composites (MQDC), in analogy to multiple-quantum-well devices [3]. Nonlinear optical materials based on glasses are intrinsically attractive for photonic-device applications owing to their high transparency, ease of fabrication, durability and thermomechanical stability. Moreover, it should be mentioned the compatibility of materials and fabrication processes with silicon-based electronic materials.
All optical wavelength conversion schemes for increased input power dynamic range
Authors: Hansen P.B. , Danielsen S.L. , Joergensen C. , Stubkjaer K.E. , Schilling M. , Wünstel K. , Idler W. , Doussiere P. , Pommerau F.
Published: February 2023

Optical wavelength converters will provide both flexibility and efficiency to future WDM networks due to the ability to allocate wavelengths on a link-to-link basis which in turn relaxes requirements to management and wavelength precision [1]. This has lead to a considerable attention to wavelength converters. Although different converters have been proposed the most promising seems to be the interferometric wavelength converters that use semiconductor optical amplifiers (SOAs) in interferometric structures such as Michelson (MI) and Mach-Zehnder (MZI) configurations [2]. These converters can be operated at high speed [3], they have low chirp [4,5] as well as regenerative capabilities [6] and are wavelength independent [5].
Crosstalk Induced Interferometric Noise Performance Degradation of Dilated Optical TDM Switching Architectures
Authors: Gilfedder T.H. , Hunter D.K. , Andonovic L
Published: February 2023

Optical switching techniques are beginning to play an important role in the evolution of future high bit rate transparent networks. It has been demonstrated experimentally that the power penalty performance of a variety of optical networks implementations significantly degrades due to the presence of phase-induced interferometric noise (PIIN) [1]. Specifically prototype optical crossconnects have been found to suffer from crosstalk induced interferometric noise [2]. Here a theoretical framework for the analysis of the causes and effects of PIIN is presented, together with a brief description of a software package that is able to determine the effect of this noise on the performance of optical networks. Results concerning the performance of a particular family of optical TDM architectures are given.
TDM 100Gbit/s Packet Switching in An Optical ShuffletNet
Authors: Yu B.Y. , Runser R. , Toliver P. , Deng K.-L. , Zhou D. , Chang T. , Seo S.W. , Kang K. , Glesk I. , Prucnal P.R.
Published: February 2023

We developed an ultra-fast node controller using a combination of optical and electronic processing. The prototype system includes high-speed packet generation with large-scale optical packet compression. The mode locked laser system, Nd:YLF, operates at 100 MHz repetition rate with a pulse width of about 100 ps and a carrier wavelength at 1.3 μm. We compress the pulses to 1-ps width, and then the pulse trains are modulated with an E/O modulator by the 100 Mb/s electronic data streams generated from a customized packet generation unit before they are compressed into 100 Gb/s optical packets. It is noted that due to the SOA relaxation time in the TOAD, the packet-to-packet time interval should be at least 500 ps to avoid saturation. Once the packets arrive at the destination they are downconverted from 100 Gb/s to an electronically processable 100 Mb/s rate.
Room Temperature Persistent Spectral Hole Burning using Dielectric Particles as Photonic Atoms
Authors: Arnold S.
Published: February 2023

Persistent spectral hole burning at room temperature has recently been demonstrated using a 2-D collection of fluorescent spherical microparticles having a random distribution of sizes.1 In this system, known as a Microparticle Hole Burning Medium(MHBM), the differences in the frequencies of Morphology Dependent Resonances(MDR) with size enables one to generate a fluorescence excitation spectrum which is heterogeneous.
Incoherent Light Read-Out of Spectral Holograms
Authors: Débarre A. , Keller J.-C. , Le Gouët J.-L. , Tchénio P.
Published: February 2023

It is known that one has investigated two types of approach to Persistent Spectral Hole Burning (PHB), and to potential application for optical data storage. In both methods, a structure is stored within the inhomogeneously broadened optical absorption line of the guest ions or molecules in a host matrix at low temperature.
Spectral Hole-Burning in the Storage Hierarchy ?
Authors: Hoyt Roger F.
Published: February 2023

The challenges and opportunities for a spectral hole-burning-based storage device are discussed in the environment of contemporary computer systems which rely on a hybrid 'Storage Hierarchy' for high capacity and performance.
Persistent Hole Burning Spectroscopy Applications On Phthalocyanine Langmuir-Blodgett Films
Authors: Adamec F. , Ambroz M. , Brynda E. , Dian J. , Vacha M. , Hala J.
Published: February 2023

Phthalocyanine Lanngmuir Blodgett (LB) films represent ultra thin monomolecular layers with molecules in tight contact. Most of the phthalocyanine molecules in LB films are ordered in domains where they occupy well defined (parallel) positions. There is also a minority of non-ordered molecules in off-domain positions in LB films. This fact is well documented in X-ray diffraction and transmission electron diffraction [1]. Moreover, significant inhomogeneous broadening of absorption spectra of LB film has been observed (see fig. 1), in comparison with absorption spectra of isolated molecules. On the other hand the observed fluorescence is very weak, nevertheless its spectral profile well corresponds to that of isolated molecules. This phenomenon can be well explained on the basis of strong aggregation and/or fast excited energy transfer (EET) [2]. Persistent hole burning (PHB) (in fluorescence excitation spectra) has recently been applied on LB film of related porphyrin - poly-heptyl-cyanoacrylate matrix [3]. The PHB study of tetraaazoporphyrin in LB films suggested this EET interpretation. The role of EET in free base phthalocyanines was also discussed in [4] together with the analysis of off-resonant holes in fluorescence spectra. The aim of this paper is to determine the excited state lifetimes T1 strongly influenced by fast EET from PHB measurements (in fluorescence excitation spectra).