Showing papers by "Amnon Yariv published in 2004"
TL;DR: An analytical expression for pulse propagation through a semi-infinite CROW in the case of weak coupling is obtained which fully accounts for the nonlinear dispersive characteristics.
Abstract: We use the coupling matrix formalism to investigate continuous-wave and pulse propagation through microring coupled-resonator optical waveguides (CROWs). The dispersion relation agrees with that derived using the tight-binding model in the limit of weak inter-resonator coupling. We obtain an analytical expression for pulse propagation through a semi-infinite CROW in the case of weak coupling which fully accounts for the nonlinear dispersive characteristics. We also show that intensity of a pulse in a CROW is enhanced by a factor inversely proportional to the inter-resonator coupling. In finite CROWs, anomalous dispersions allows for a pulse to propagate with a negative group velocity such that the output pulse appears to emerge before the input as in “superluminal” propagation. The matrix formalism is a powerful approach for microring CROWs since it can be applied to structures and geometries for which analyses with the commonly used tight-binding approach are not applicable.
416 citations
TL;DR: In this paper, a method for the fabrication of functional microstructured optical fibers (MOFs) by selectively filling the air holes with liquid phase materials, where the dependence of filling speed on the size of the air hole was exploited.
Abstract: We develop a method for the fabrication of functional microstructured optical fibers (MOFs) by selectively filling the air holes with liquid phase materials, where we utilize the dependence of filling speed on the size of the air holes. As a demonstration, we construct a hybrid MOF by filling the center hollow core of a triangular lattice photonic crystal fiber with dye-doped curable polymer, and experimentally observe the two-photon fluorescence from the hybrid MOF.
295 citations
TL;DR: In this paper, the trade-offs among delay, loss, and bandwidth in the design of coupled-resonator optical waveguide (CROW) delay lines were discussed.
Abstract: We address the trade-offs among delay, loss, and bandwidth in the design of coupled-resonator optical waveguide (CROW) delay lines. We begin by showing the convergence of the transfer matrix, tight-binding, and time domain formalisms in the theoretical analysis of CROWs. From the analytical formalisms we obtain simple, analytical expressions for the achievable delay, loss, bandwidth, and a figure of merit to be used to compare delay line performance. We compare CROW delay lines composed of ring resonators, toroid resonators, Fabry-Perot resonators, and photonic crystal defect cavities based on recent experimental results reported in the literature.
294 citations
TL;DR: A new class of hollow-core Bragg fibers that are composed of concentric cylindrical silica rings separated by nanoscale support bridges are demonstrated that achieve propagation loss of the order of 1 dB/m.
Abstract: We demonstrate a new class of hollow-core Bragg fibers that are composed of concentric cylindrical silica rings separated by nanoscale support bridges. We theoretically predict and experimentally observe hollow-core confinement over an octave frequency range. The bandwidth of bandgap guiding in this new class of Bragg fibers exceeds that of other hollow-core fibers reported in the literature. With only three rings of silica cladding layers, these Bragg fibers achieve propagation loss of the order of 1 dB/m.
121 citations
TL;DR: In this article, the coupling between the straight waveguide and the microring resonator is precisely controlled, and the critical coupling condition can be achieved, and a short 2mm active-section prototype Mach−Zehnder interferometer modulator is made by the replica molding process, using CLD-1/APC electrooptic polymer as the core material.
Abstract: Polymeric integrated optical devices, including microring resonator optical filters and Mach−Zehnder interferometer modulators, fabricated by electron-beam lithography and soft lithography are considered in this article. Microring resonator optical filters made of SU-8 (MicroChem, Newton, MA), directly patterned by electron-beam lithography, demonstrate that SU-8 is a good candidate for high-precision, easily fabricated, and good-optical-quality passive integrated optical devices. Due to the electron-beam lithography process, the coupling between the straight waveguide and the microring resonator is precisely controlled, and the critical coupling condition can be achieved. Additionally, films containing several devices patterned by electron-beam lithography are peeled from the silicon substrate, yielding ultrathin all-polymer flexible free-standing microring resonator optical filters exhibiting up to −27 dB filtering extinction. Using a PDMS stamp, molded from these electron-beam-patterned microring resonator optical filters, identical replicas are fabricated by the soft lithography molding technique. Soft lithography is also applied to active polymer materials. A short 2-mm active-section prototype Mach−Zehnder interferometer modulator is made by the replica molding process, using CLD-1/APC electrooptic polymer as the core material. A reasonable intensity-modulation effect is observed by applying voltage to one arm of the interferometer.
118 citations
TL;DR: In this paper, a novel type of wavelength-selective reflector for planar lightwave technology based on a circular array of coupled microring resonators is proposed and analyzed.
Abstract: We propose and analyze a novel type of wavelength-selective reflector for planar lightwave technology based on a circular array of coupled microring resonators. Narrow-band reflection peaks can be achieved without the need for additional complex lithography and processing steps. The ring resonators also allow for simple and wide-range tuning of the reflection peak.
106 citations
TL;DR: In this paper, a Mach-Zehnder electro-optic polymer amplitude modulator is fabricated by a simple and high-throughput soft-stamp replica-molding technique.
Abstract: A Mach-Zehnder electro-optic polymer amplitude modulator is fabricated by a simple and high-throughput soft-stamp replica-molding technique. The modulator structure incorporates the highly nonlinear and stable chromophore, AJL8, doped in amorphous polycarbonate. Single-arm phase-retardation results in a halfwave voltage (V-pi) of 8.4 V at 1600 nm. The on/off extinction ratio is better than 19 dB, resulting from precise Y-branch power splitters and good waveguide uniformity. These results indicate that the simple fabrication process allows for good optical performance from high-fidelity replicas of the original master devices.
75 citations
TL;DR: In this article, the authors used soft lithography replica molding to fabricate unclad polystyrene (PS) and clad SU-8 microring resonator filters, which showed the practicality of soft-lithography replica moulding for the fabrication of integrated optical devices.
Abstract: We use soft lithography replica molding to fabricate unclad polystyrene (PS) and clad SU-8 microring resonator filters. The PS resonator has an intrinsic quality factor of 1.0/spl times/10/sup 4/ at /spl lambda/=1.55 /spl mu/m, while that of the SU-8 resonator is 7100. The extinction ratios of the PS and SU-8 microring filters are -12 and -20 dB, respectively, with net insertion losses of 6.7 and 9.9 dB. The good quality factors and high extinction ratios of the microring resonator filters show the practicality of soft-lithography replica molding for the fabrication of integrated optical devices.
69 citations
TL;DR: Lasing at telecommunication wavelengths from annular resonators employing radial Bragg reflectors is demonstrated at room temperature under pulsed optical pumping, and the electromagnetic field is shown to be guided by the defect.
Abstract: Lasing at telecommunication wavelengths from annular resonators employing radial Bragg reflectors is demonstrated at room temperature under pulsed optical pumping Submilliwatt pump threshold levels are observed for resonators with 05-15-wavelength-wide defects of radii 7-8 µm The quality factors of the resonator modal fields are estimated to be of the order of a few thousand The electromagnetic field is shown to be guided by the defect Good agreement is found between the measured and the calculated spectra
52 citations
TL;DR: A simple and effective method for the postfabrication trimming of optical microresonators by photobleach CLD-1 chromophores to tune the resonance wavelengths of polymer microring resonator optical notch filters.
Abstract: We present a simple and effective method for the postfabrication trimming of optical microresonators. We photobleach CLD-1 chromophores to tune the resonance wavelengths of polymer microring resonator optical notch filters. A maximum wavelength shift of ~8.73 nm is observed. The resonators are fabricated with a soft-lithography molding technique and have an intrinsic Q value of 2.6 x 10^4 and a finesse of 9.3. The maximum extinction ratio of the resonator filters is ~34 dB, indicating that the critical coupling condition has been satisfied.
44 citations
TL;DR: Good agreement is found between the analytical and the numerical results obtained by finite-difference time-domain simulations of a new class of circular resonators based on a radial photonic crystal reflector.
Abstract: We study analytically and numerically a new class of circular resonators based on a radial photonic crystal reflector. The Bragg confinement enables the realization of compact resonators exhibiting both large free spectral range and high $Q$-factor. The dependence of the resonator characteristics on the reflector architecture and dimensions is studied in detail. Good agreement is found between the analytical and the numerical results obtained by finite-difference time-domain simulations.
Proceedings Article•
22 Feb 2004TL;DR: In this article, the TE/sub 01/mode was observed for the first time to our knowledge in air-silica Bragg fibers, and it could transmit light by bandgap guiding over 50 m.
Abstract: We present experimental and theoretical results on air-silica Bragg fibers. The TE/sub 01/ mode is observed for the first time to our knowledge in Bragg fibers. We could transmit light by bandgap guiding over 50 m.
TL;DR: In this article, a planar semiconductor microcavity, composed of cylindrical Bragg reflectors surrounding a radial defect, is constructed using a versatile polymer bonding process to transfer active InGaAsP resonators to a low-index transfer substrate.
Abstract: Fabrication of a planar semiconductor microcavity, composed of cylindrical Bragg reflectors surrounding a radial defect, is demonstrated. A versatile polymer bonding process is used to transfer active InGaAsP resonators to a low-index transfer substrate. Vertical emission of in-plane modes lasing at telecom wavelengths is observed under pulsed optical excitation with a submilliwatt threshold.
Patent•
29 Jan 2004TL;DR: In this paper, a closed loop resonator with a distributed Bragg reflector is proposed to confine the light within the guiding core, which can be used in various applications such as optical filters, lasers, modulators, spectrum analyzers, wavelockers, interleave filters, and optical add drop multiplexers.
Abstract: A resonator structure is presented comprising a closed loop resonator having a distributed Bragg reflector for confining the light within the guiding core. In one embodiment the light is confined from both the internal and the external sides of the device forming a guiding channel (defect) or just by the external side forming a disk resonator. Although the perfectly circular shape is generally preferred, the resonator could be of any closed loop shape such as an ellipse, etc. Although not mentioned explicitly throughout the text, the Bragg reflectors can of any type of distributed reflector such as, for example, a photonic bandgap crystal where the Bragg reflector is constructed by series of holes in a dielectric material. The resonator structure can be used in various applications, such as optical filters, lasers, modulators, spectrum analyzers, wavelockers, interleave filters, and optical add drop multiplexers.
TL;DR: In this paper, the authors proposed a new type of resonator in an annular geometry which is based on a single defect surrounded by radial Bragg reflectors on both sides.
Abstract: We propose and analyze a new type of resonator in an annular geometry which is based on a single defect surrounded by radial Bragg reflectors on both sides. Unlike conventional, total internal reflection based ring resonators, this structure supports modal fields with very low azimuthal number (large radial k-vector component). We show that the conditions for efficient mode confinement are different from those of conventional Bragg waveguiding in a rectangular geometry. To realize tight confinement of the light in the defect, chirped gratings are required. Compared to a conventional resonator, the new resonator exhibits larger FSR and lower losses making it suitable for both telecom and sensing applications. In addition, the resonance wavelength and Q factor of the device are very sensitive to environmental changes, and thus provide ideal observables for sensing applications. Annular Bragg resonators with several unique geometries have been fabricated in an InGaAsP multi-quantum-well membrane. The spectral properties of the resonators have been investigated through analysis of photoluminescence induced by pulsed optical excitation.
TL;DR: Combining the Mie scattering theory and a transfer matrix method, the scattering of light by spherical Bragg "onion" resonators is investigated in detail, demonstrating that these two types of modes lead to significantly different scattering behaviors.
Abstract: Combining the Mie scattering theory and a transfer matrix method, we investigate in detail the scattering of light by spherical Bragg “onion” resonators. We classify the resonator modes into two classes, the core modes that are confined by Bragg reflection, and the cladding modes that are confined by total internal reflection. We demonstrate that these two types of modes lead to significantly different scattering behaviors.
TL;DR: This work shows that, in the (1 + 1)-D case, both soliton and propagation-invariant pattern solutions exist (while the standard hyperbolic-secant function is not a solution).
Abstract: We investigate nonlinear propagation in the presence of the optical Kerr effect by relying on a rigorous generalization of the standard parabolic equation that includes nonparaxial and vectorial terms. We show that, in the (1 + 1)-D case, both soliton and propagation-invariant pattern solutions exist (while the standard hyperbolic-secant function is not a solution).
TL;DR: It is demonstrated that onion resonators are ideal for applications that require a large spontaneous-emission factor beta, such as thresholdless lasers and single-photon devices.
Abstract: From analysis of the high Q modes in a Bragg onion resonator with an omnidirectional reflector cladding, we establish a close analogy between such a resonator and a spherical hollow cavity in perfect metal. We demonstrate that onion resonators are ideal for applications that require a large spontaneous-emission factor s, such as thresholdless lasers and single-photon devices.
TL;DR: In this article, the authors investigated the wavelength insensitivity and fabrication error tolerance of a new type of optical coupler, which overcomes the long-length requirements of adiabatic couplers, yet achieves similar desirable properties.
Abstract: We investigate the wavelength insensitivity and fabrication error tolerance of the relative output amplitude and phase for a new type of optical coupler. This new coupler overcomes the long-length requirements of adiabatic couplers, yet achieves similar desirable properties. The three-space geometrical representation of coupled-mode theory, used as the design and analysis method, is presented and an example of a 3-dB coupler is examined.
TL;DR: In this paper, the modal properties of an individual waveguide, the coupling ratio of a directional coupler, and the radiation loss in a waveguide bend are investigated numerically.
Abstract: Soft lithography molding is a promising technique for patterning polymer integrated optical devices, however the presence of a background residue has the potential to limit the usefulness of this technique. We present the soft lithography technique for fabricating polymer waveguides. Several effects of the background residue are investigated numerically, including the modal properties of an individual waveguide, the coupling ratio of a directional coupler, and the radiation loss in a waveguide bend. Experimentally, the residue is found to be reduced through dilution of the core polymer solution. We find that the force with which the soft mold is depressed on the substrate does not appreciably affect the waveguide thickness or the residue thickness. Optical microscope images show that the residue is thinnest next to the waveguide.
TL;DR: In this article, a method to efficiently fabricate three-dimensional multilayer polymer microchips for integrated optical applications was developed, which uses soft lithography to mold the core structures on top of the cladding layers.
Abstract: We develop a method to efficiently fabricate three-dimensional multilayer polymer microchips for integrated optical applications. This method uses soft lithography to mold the core structures on top of the cladding, layers. By repeating the process, a three-dimensional multilayer integrated optical microdevice, which consists of several layers of individual planar optical devices, is fabricated. We demonstrate a dual-layer microring resonator optical filter device where the devices in the different layers show essentially identical transmission responses.
TL;DR: Direct electron beam writing is applied to fabricate corrugated sidewall Bragg gratings in polymer waveguides and multi-channel passband filters based on a phase-shifted design are demonstrated.
Abstract: We apply direct electron beam writing to fabricate corrugated sidewall Bragg gratings in polymer waveguides and demonstrate multi-channel passband filters based on a phase-shifted design. Experimental results are compared with numerical fittings to analyze the impact of signal polarization and waveguide cladding material upon device performance.
TL;DR: In this article, the effect of lithographic process variation upon device performance is studied and the resonance wavelength and threshold optical pump power are found to vary between similar devices given different electron doses during electron-beam lithography.
Abstract: Optical microresonators based on an annular geometry of radial Bragg reflectors have been designed and fabricated by electron-beam lithography, reactive ion etching, and an epitaxial transfer process. Unlike conventional ring resonators that are based on total internal reflection of light, the annular structure described here is designed to support optical modes with very small azimuthal propagation coefficient and correspondingly large free spectral range. The effect of lithographic process variation upon device performance is studied. Laser emission wavelength and threshold optical pump power are found to vary between similar devices given different electron doses during electron-beam lithography. As the resonance wavelength and quality factor of these resonators are very sensitive to environmental changes, these resonators make ideal active light sources that can be integrated into large arrays for gas and liquid sensing applications and are easily interrogated.
TL;DR: In this paper, a new type of a resonator in an annular geometry is proposed and analyzed, based on a single defect surrounded by radial Bragg reflectors on both sides.
Abstract: We propose and analyze a new type of a resonator in an annular geometry which is based on a single defect surrounded by radial Bragg reflectors on both sides. We show that the conditions for efficient mode confinement are different from those of the conventional Bragg waveguiding in a rectangular geometry. A simple and intuitive approach to the design of optimal radial Bragg reflectors is proposed and employed, yielding chirped gratings. Small bending radii and strong control over the resonator dispersion are possible by the Bragg confinement. A design compromise between large Free Spectral Range (FSR) requirements and fabrication tolerances is suggested.
TL;DR: Two-dimensional finite-difference time-domain simulations of the TBR waveguide show good quantitative agreement with the coupled-mode predictions, and these results corroborate the previously predicted existence of discrete core widths for low-loss propagation.
Abstract: Coupled-mode theory was used to analyze guiding in a transverse Bragg resonance (TBR) waveguide structure composed of a GaAs substrate with air holes. This analysis predicts that propagation loss will be minimized for discrete widths of the waveguide core. Although the coupled-mode theory is normally applied to structures with small index perturbations, two-dimensional finite-difference time-domain simulations of the TBR waveguide show good quantitative agreement with the coupled-mode predictions, and these results corroborate the previously predicted existence of discrete core widths for low-loss propagation.
TL;DR: In this article, an annular resonator employing radial Bragg reflectors is demonstrated at room temperature under pulsed optical pumping, and good agreement is found between the measured and calculated spectrum.
Abstract: Lasing at telecommunication wavelengths from annular resonators employing radial Bragg reflectors is demonstrated at room temperature under pulsed optical pumping. Sub milliwatt pump threshold levels are observed for resonators with 0.5-1.5 wavelengths wide defects of radii 7-8 mm. The quality factors of the resonator modal fields are estimated to be on the order of a few thousands. The electromagnetic field is shown to be guided by the defect. Good agreement is found between the measured and calculated spectrum.
Patent•
23 Jan 2004TL;DR: In this paper, a transverse Bragg resonance waveguide (14) is comprised of a waveguiding channel and on at least two opposing sides of the channel two periodic index media.
Abstract: A transverse Bragg resonance waveguide (14) is comprised of a waveguiding channel (22), and on at least two opposing sides of the channel two periodic index media (24); and a means for providing gain in the periodic index media. In one embodiment the waveguiding channel is planar and is sandwiched on two opposing sides by the periodic index media. In another embodiment the waveguiding channel is cylindrical and is surrounded by the periodic index media. The means for providing gain in the periodic index media is electrical or optical pumping. The periodic index media comprises a periodic lattice (18) of regions having an index of refraction distinct from the channel, such as an array of transverse holes (16) defined in a planar semiconductor substrate in which the channel is also defined, or an array of longitudinal holes defined in a cylindrical semiconductor fiber in which the channel is also longitudinally defined.
TL;DR: The optimization of a second-order, feedforward polarization-mode dispersion compensation scheme is described by reducing its degrees of freedom by two, which is optimal in the sense that the number of DOF used is the same as the minimal number ofDOF required.
Abstract: As an extension to a previous paper, this paper describes the optimization of a second-order, feedforward polarization-mode dispersion (PMD) compensation scheme by reducing its degrees of freedom (DOF) by two. The new design is optimal in the sense that the number of DOF used is the same as the minimal number of DOF required. Also derived is a set of constraint equations that govern the choice of various system parameters.
09 Jul 2004
TL;DR: In this article, onion-like resonators were used to approximate spherically symmetric Bragg resonators and achieved Q factor exceeding 5 × 106 in a cavity of a few microns in dimension.
Abstract: We propose to use onion-like resonators to approximate spherically symmetric Bragg resonators. Such Bragg onion resonators have been realized in silicon based material systems. We develop an analytical theory that calculates the resonant frequencies and the quality factors of the onion cavity modes. We demonstrate that it is possible to achieve Q factors exceeding 5 x 106 in a cavity of a few microns in dimension. The onion resonators allow full control over the spontaneous emission process, which may lead to the thresholdless lasers. The onion resonators may also find many other applications in cavity quantum electrodynamics.