Showing papers on "Single-mode optical fiber published in 1999"
TL;DR: The confinement of light within a hollow core (a large air hole) in a silica-air photonic crystal fiber is demonstrated and certain wavelength bands are confined and guided down the fiber.
Abstract: The confinement of light within a hollow core (a large air hole) in a silica-air photonic crystal fiber is demonstrated Only certain wavelength bands are confined and guided down the fiber, each band corresponding to the presence of a full two-dimensional band gap in the photonic crystal cladding Single-mode vacuum waveguides have a multitude of potential applications from ultrahigh-power transmission to the guiding of cold atoms
1,935 citations
TL;DR: In this article, the authors asserted that the research and development of chalcogenide glasses will grow in the foreseeable future, especially with respect to improvements in the optical quality of the fibers and the performance of the fiber in existing and future applications.
Abstract: Chalcogenide glass fibers based on sulfide, selenide, telluride and their rare earth doped compositions are being actively investigated worldwide. Great strides have been made in reducing optical losses using improved chemical purification techniques, but further improvements are needed in both purification and fiberization technology to attain the theoretical optical losses. Despite these problems, current single mode and multimode chalcogenide glass fibers are enabling numerous applications. Some of these applications include laser power delivery, chemical sensing, imaging, scanning near field microscopy/spectroscopy, fiber IR sources/lasers, amplifiers and optical switches. The authors assert that the research and development of chalcogenide glasses will grow in the foreseeable future, especially with respect to improvements in the optical quality of the fibers and the performance of the fibers in existing and future applications.
460 citations
Patent•
05 Oct 1999TL;DR: In this article, an endoscopic system for performing optical coherence tomography includes an optical radiation source; a reference optical reflector; a first optical path leading to the reference optical reflectedor; and a second optical path coupled to an endoscopy unit.
Abstract: An imaging system for performing optical coherence tomography includes an optical radiation source; a reference optical reflector; a first optical path leading to the reference optical reflector; and a second optical path coupled to an endoscopic unit. The endoscopic unit preferably includes an elongated housing defining a bore; a rotatable single mode optical fiber having a proximal end and a distal end positioned within and extending the length of the bore of the elongated housing; and an optical system coupled to the distal end of the rotatable single mode optical fiber, positioned to transmit the optical radiation from the single mode optical fiber to the structure and to transmit reflected optical radiation from the structure to the single mode optical fiber. The system further includes a beam divider dividing the optical radiation from the optical radiation source along the first optical path to the reflector and along the second optical path; and a detector positioned to receive reflected optical radiation from the reflector transmitted along the first optical path and reflected optical radiation transmitted from the structure along the second optical path. The detector generates a signal in response to the reflected optical radiation from the reference reflector and the reflected optical radiation from the structure, and a processor generating a image of the structure in response to the signal from the detector. The system provides both rotational and longitudinal scanning of an image.
406 citations
TL;DR: In this paper, a single-mode optical fiber switch which routes individual signals into and out of a wavelength multiplexed data stream without interrupting the remaining channels is described, and the total fiber-to-fiber insertion loss for the packaged switch is 5 dB for passed signals and 8 dB for added and dropped signals, with 0.2 dB polarization dependence.
Abstract: This paper describes a single-mode optical fiber switch which routes individual signals into and out of a wavelength multiplexed data stream without interrupting the remaining channels. The switch uses free-space optical wavelength multiplexing and a column of micromechanical tilt-mirrors to switch 16 channels at 200 GHz spacing from 1531 to 1556 nm. The electrostatically actuated tilt mirrors use an 80 V peak-to-peak 300 KHz sinusoidal drive signal to switch between /spl plusmn/10/spl deg/ with a 20 /spl mu/s response. The total fiber-to-fiber insertion loss for the packaged switch is 5 dB for the passed signals and 8 dB for added and dropped signals, with 0.2 dB polarization dependence. Switching contrast was 30 dB or more for all 16 channels and all input and output states. We demonstrate operation by switching 622 Mb/s data on eight wavelength channels between the two input and output ports with negligible eye closure.
334 citations
01 Jan 1999
TL;DR: In this article, the authors present an overview of the development of optical fiber sensor technology and its application in the field of temperature measurement and current measurement, as well as other applications.
Abstract: List of contributors. Preface. 1. Overview of fiber sensor developments D.A. Jackson. 2. Foundations of optical fiber technology V. Handerek. 3. Sources for optical fiber sensors K.T.V. Grattan. 4. Optical detectors and receivers J.D.C. Jones. 5. Multimode optical fiber sensors G.R. Jones, R.E. Jones, R. Jones. 6. Multimode optical fiber chemical sensors J.O.W. Norris. 7. Single mode optical fiber sensors V. Handerek. 8. Optical fiber modulation techniques for single mode fiber sensors R.P. Tatam. 9. Fiber optic white-light interferometric sensors B.T. Meggitt. 10. Nonlinear effects in optical fibers A.J. Rogers. 11. Distributed fiber optic sensors A.H. Hartog. 12. Schemes for referencing of intensity-modulated optical sensor systems G. Murtaza, J.M. Senior. 13A. Hybrid optical fiber sensors R.C. Spooncer, G.S. Philp. 13B. Optical fiber current measurement A.J. Rogers. 13C. Fiber optic techniques for temperature measurement K.T.V. Grattan. 14. Advanced external fiber optic sensors D.A. Jackson. Index.
284 citations
TL;DR: This work analyzes the guiding problem in a realistic photonic crystal fiber, using a novel full-vector modal technique based on the non-self-adjoint character of the electromagnetic propagation in a fiber, which matches those achieved in recent experiments.
Abstract: We analyze the guiding problem in a realistic photonic crystal fiber, using a novel full-vector modal technique. This is a biorthogonal modal method based on the non-self-adjoint character of the electromagnetic propagation in a fiber. Dispersion curves of guided modes for different fiber structural paremeters are calculated, along with the two-dimensional transverse intensity distribution of the fundamental mode. Our results match those achieved in recent experiments in which the feasibility of this type of fiber was shown.
242 citations
TL;DR: In this article, a variable optical attenuator for single mode fibers is described, which operates by moving an obstructing element in the optical beam in order to adjust the light damping.
Abstract: In this letter, we describe a variable optical attenuator for single mode fibers. As for its counterparts based on conventional mechanics the micromechanical attenuator operates by moving an obstructing element in the optical beam in order to adjust the light damping. The device is fabricated using the silicon micromachining technology. This allows one to integrate the electrostatic actuator together with the fiber alignment grooves and the obstructing element. With this design, an insertion loss below 1.5 dB was achieved. The response time was below 5 ms and no hysteresis was measured. The maximum attenuation was -57 dB. Backreflection attenuation was below -37 dB.
191 citations
TL;DR: In this paper, a fiber optic surface plasmon resonance (SPR) sensor utilizing the resonant interaction between a guided mode of a singlemode optical fiber and a surface plasma wave supported by a thin metal film is described.
Abstract: A fiber optic surface plasmon resonance (SPR) sensor utilizing the resonant interaction between a guided mode of a single-mode optical fiber and a surface plasma wave supported by a thin metal film is described. Theoretical analysis of the SPR sensing structure based on the equivalent planar waveguide approach and the mode expansion and propagation method is presented. A detailed analysis of the effect of the major parameters of the SPR sensing structure on the sensor performance is carried out. Experimental results obtained with fabricated laboratory prototypes of the SPR sensing device for measurement of the refractive index of analyte are reported. It has been demonstrated that the fiber optic SPR sensing device may be used as a spectral as well as an amplitude sensor.
187 citations
TL;DR: In this paper, a 2/spl times/2 switch for single-mode fibers is presented, which is based on a vertical micro-mirror which can be moved into the optical path to switch light between two pairs of fibers.
Abstract: This paper reports on a new optical 2/spl times/2 switch for single-mode fibers. The switching principle is based on a vertical micro-mirror which can be moved into the optical path to switch light between two pairs of fibers. The micromirror switch is designed for by-pass applications. When power is turned off the mirror spring back into its rest position and brings the switch into its bar state. This operation is very reliable, since the moving parts do not get into contact. Fabrication is based on the silicon micromachining technology, which allows to integrate the switching mirror, its electrostatic actuator and the alignment grooves for the fibers on the same chip. The mechanical switching principle brings with it a number of optical advantages such as a high crosstalk attenuation above 50 dB and wavelength and polarization insensitivity. At a wavelength of 1310 nm a minimum insertion loss of 0.6 dB was measured in the bar state, i.e. when the mirror is out of the optical path. In the cross state the light is reflected on the gold coated micro-mirror which has a reflectivity of about 80%. The insertion loss of the bar state was thus higher and a minimum value of 1.6 dB could be obtained. The switching time was well below 1 ms.
175 citations
TL;DR: In this paper, a very compact wavelength converter module has been demonstrated by using the fiber, and highly nonlinear dispersion-shifted fibers have been developed, and Dispersion-flattened and dispersiondecreasing fibers have also been proved to be highly effective for supercontinuum generation.
Abstract: Silica-based optical fibers are now being used in various applications which utilize nonlinear effects in fiber. In addition to enhancing nonlinearity of optical fibers, tailoring chromatic dispersion is one of the important design issues in such applications. Highly nonlinear dispersion-shifted fibers have been developed, and a very compact wavelength converter module has been demonstrated by using the fiber. Dispersion-flattened and dispersion-decreasing fibers have also been proved to be highly effective for supercontinuum generation.
163 citations
TL;DR: In this article, a fiber-optic mm-wave downlink system using 60 GHz-band external modulation is investigated, where a specially designed electro-absorption modulator with high-efficiency at around 60 GHz is used.
Abstract: In this paper, a fiber-optic millimeter-wave (mm-wave) downlink system using 60 GHz-band external modulation is investigated. We prepare the fiber-optic 60 GHz-band mm-wave downlink testbed. It consists of an optical modulation section with a mm-wave signal generator, an optical single sideband (SSB) filter, a standard single-mode fiber (SMF), an optical detection section with a 60 GHz-band radio transmitter and a 60 GHz-band radio receiver. To modulate the laser output with 60 GHz-band mm-wave signals directly, a specially designed electro-absorption modulator with high-efficiency at around 60 GHz is used. The use of this modulator makes the simpler system configuration possible. Using the downlink testbed, the 5 m-long free-space propagation of subcarrier multiplexed 156 Mb/s-DPSK 60 GHz-band mm-wave signals recovered by optical direct detection is successfully demonstrated. The transmission of the mm-wave signals over 85 km-long standard SMF is also successfully demonstrated, using an optical SSB filtering technique to overcome the fiber dispersion. The BER of 10/sup -9/ is achievable at the optical received power of -7.0 dBm.
TL;DR: A general formula for determining the coupling loss between two single-mode fiber collimators with the simultaneous existence of separation, lateral offset and angular tilt mis alignment, and spot-size mismatch is theoretically derived by use of the Gaussian field approximation.
Abstract: A general formula for determining the coupling loss between two single-mode fiber collimators with the simultaneous existence of separation, lateral offset and angular tilt misalignments, and spot-size mismatch is theoretically derived by use of the Gaussian field approximation. Based on this general formula, the formulas for coupling losses that are due to the misalignment of insert separation, lateral offset, and angular tilt are given. The formula for the coupling loss that is due to Gaussian spot-size mismatch of two single-mode collimators is also given. Good agreement between these formulas and experimental results is demonstrated with gradient-index rod lens-based fiber collimators operating in the 1300-nm band.
TL;DR: This work describes how to calculate the Jones matrix transfer function of a fiber if its principal states of polarization and its differential group delay as functions of frequency are known and shows that a previous method used for this purpose induces overestimation of second-order PMD effects.
Abstract: We describe how to calculate the Jones matrix transfer function of a fiber if its principal states of polarization and its differential group delay as functions of frequency are known. Using two counterexamples related to second-order polarization mode dispersion (PMD), we also show that a previous method used for the same purpose induces overestimation of second-order PMD effects by a factor of 2. Our new method is used to solve the problem for both counterexamples.
21 Feb 1999
TL;DR: In this paper, a polarization-mode dispersion (PMD) transient recorder setup was realized enabling for the first time to the knowledge the monitoring of fast PMD fluctuation with a bandwidth of up to 1 MHz.
Abstract: A polarization-mode dispersion (PMD) transient recorder setup was realized enabling for the first time to our knowledge the monitoring of fast PMD fluctuation with a bandwidth of up to 1 MHz. Thirty-six hours of observation of an installed field fiber exhibits significant PMD variation within 10 ms.
TL;DR: In this article, the authors investigated the noise properties of single and multimode VCSELs under different operation conditions and showed that the relative intensity noise of single-mode devices can be as low as -150 dB/Hz at output powers of about 1 mW and feedback levels up to -30 dB.
Abstract: Oxide-confined vertical-cavity surface-emitting laser diodes (VCSELs) are fabricated for applications in high-performance optical interconnects. Both 980-nm as well as 850-nm wavelength devices in one- and two-dimensional arrays are investigated. Noise properties of single- and multimode devices under different operation conditions are relative intensity noise of single-mode devices can be as low as -150 dB/Hz at output powers of about 1 mW and feedback levels up to -30 dB. Data rates up to 12.5 Gb/s with bit error rates below 10/sup -11/ are achieved with VCSELs showing stable single-mode emission at large-signal modulation, combined with modulation bandwidths exceeding 10 GHz. Arrays with 4/spl times/8 elements flip-chip mounted on Si CMOS driver chips ready for use in parallel data transmission systems are presented.
Posted Content•
TL;DR: In this article, the quantum dynamics of radiation propagating in a single mode optical fiber with dispersion, nonlinearity, and Raman coupling to thermal phonons are analyzed.
Abstract: We analyze the quantum dynamics of radiation propagating in a single mode optical fiber with dispersion, nonlinearity, and Raman coupling to thermal phonons. We start from a fundamental Hamiltonian that includes the principal known nonlinear effects and quantum noise sources, including linear gain and loss. Both Markovian and frequency-dependent, non-Markovian reservoirs are treated. This allows quantum Langevin equations to be calculated, which have a classical form except for additional quantum noise terms. In practical calculations, it is more useful to transform to Wigner or +$P$ quasi-probability operator representations. These result in stochastic equations that can be analyzed using perturbation theory or exact numerical techniques. The results have applications to fiber optics communications, networking, and sensor technology.
TL;DR: In this article, the authors describe the development of an array of fiber laser sensors configured as hydrophones, and the design of the single mode fiber laser used throughout their system; comparing examples based upon distributed Bragg reflectors (DBR) and distributed feedback (DFB).
Abstract: In recent years growing interest has surrounded the development of fiber laser sensors (FLS). This is due to their ultra high sensitivity to temperature and strain as well as their ability to be multiplexed along a single fiber using WDM techniques. It is their extreme sensitivity that has led to them being considered as acoustic pressure sensors rather than standard fiber Bragg gratings. The work presented here describes the development of an array of FLS configured as hydrophones. We discuss the design of the single mode fiber laser used throughout our system; comparing examples based upon distributed Bragg reflectors (DBR) and distributed feedback (DFB). In addition we discuss both the theoretical and experimental acoustic sensitivity enhancements obtained by the application of an elasto-plastic coating to the FLS. The array configuration is described, as is the heterodyne interrogation scheme using an unbalanced Mach-Zehnder interferometer with WDM channel selection. Results from the measurement of the minimal detectable acoustic signal of a bare fiber laser are shown to be -69 dB re.Pa/(root)Hz at 1 kHz when using a 200 m path imbalanced readout interferometer. Further gains in the sensitivity due to the application of various coatings are reported, as is a full characterization of an array of fiber laser hydrophones. Finally we discuss the future research of the FLS, and the areas in which the technology is particularly applicable.
TL;DR: In this article, the authors investigate leaky-mode propagation of the cladding modes of an optical fiber through coupling with a long-period fiber grating and apply a one-dimensional ray propagation model.
Abstract: We investigate leaky-mode propagation of the cladding modes of an optical fiber through coupling with a long-period fiber grating. A one-dimensional ray propagation model is applied. Experimental measurements are compared to a transfer-matrix model to estimate the cladding mode losses. Losses are also measured using an all-fiber Mach-Zehnder mode interferometer. The measured losses are somewhat greater than predicted by the simple theory.
TL;DR: In this paper, the power density in the vicinity of a tapered fiber is calculated, with the vectorial model of step-index circular waveguides, for the fundamental HE11 mode carrying a power of 1 Watt, and it is possible to obtain theoretical densities in the range of 108 W/cm2 at the fiber surface.
Abstract: The power density in the vicinity of a tapered fiber is calculated, with the vectorial model of step-index circular waveguides. For the fundamental HE11 mode carrying a power of 1 Watt, we show that it is possible to obtain theoretical densities in the range of 108 W/cm2 at the fiber surface. The promising use of such intense evanescent fields as “atomic mirrors” is considered, and the feasibility of these guides is investigated.
Patent•
14 Jan 1999TL;DR: In this paper, a network for multi-bit word parallel communication between optoelectronic chips on a two-dimensional array of optical input and output channels carried on a single dimension of optical fibers is proposed.
Abstract: A network for multi-bit word parallel communication between optoelectronic chips on a two dimensional array of optical input and output channels carried on a single dimension of optical fibers. Each bit of a word is carried on a different wavelength and the multiple wavelengths carrying a word are wavelength multiplexed onto a single optical fiber. Multiple fibers can be joined into a one dimensional array of fibers. A transceiver for transmitting and receiving along the optical data channels comprises an array of modulators powered by individual wavelength light beams, either from individual monochromatic light sources and a light beam from a single broadband light source made to pass through a diffraction grating. The modulators are positioned so that each modulator reflects a different wavelength light beam, thereby providing multiple optical channels. Alternatively, multiple wavelengths are generated from CMOS integrated light sources. These multiple optical channels are then collimated and guided into one single mode fiber or multiple multimode fibers at its transmitting end. At the receiving end a diffraction grating is used to separate the distinct data channels by their individual wavelengths. The multiple wavelengths are then caused to fall on an array of optical detectors spaced according to the individual wavelengths to be detected. By constructing a one dimensional array of these fibers, a two dimensional array of optical data channels is realized. The size of the array is determined by the number of fibers and the number of distinct wavelengths combined in each fiber.
TL;DR: The birefringence of a pi -phase-shifted fiber Bragg grating can be determined with high accuracy by measurement of the polarization-induced spectral splitting of its narrow central transmission window by means of a distributed force resolution.
Abstract: The birefringence of a pi -phase-shifted fiber Bragg grating can be determined with high accuracy by measurement of the polarization-induced spectral splitting of its narrow central transmission window. The use of this feature for sensing of a load applied in the direction transverse to the optical fiber is demonstrated. A distributed force resolution of 1.4x10(-3) N/mm was obtained, which corresponds to a difference in the principal strains of the fiber core of 0.5mu? . We also show that the transverse load response of the sensor is insensitive to temperature.
TL;DR: In this article, the statistics of the eye-closure due to four-wave mixing (FWM) in the presence of arbitrary data values and optical phases in all WDM channels were evaluated.
Abstract: For wavelength division multiplexing (WDM) systems over nonzero dispersion fiber, we evaluate the statistics of the eye-closure due to four-wave mixing (FWM) in the presence of arbitrary data values and optical phases in all WDM channels. By Monte Carlo (MC) experiments, we determine the distribution function and the standard deviation of the eye-closure for several channel counts. Convolution of the distribution after a single span yields the eye-closure distribution after multiple amplified spans. The results are used to assess the Q-factor penalty in a WDM system. The limits for optical power, chromatic dispersion and channel spacing can then be found. It is shown that the power of the FWM products can be used to estimate the system penalty due to FWM. When comparing standard single-mode fiber with nonzero dispersion-shifted fiber (NZDSF), we find that standard fiber allows for a triple narrower channel spacing than NZDSF, given the same set of system parameters.
TL;DR: In this paper, the use of frequency-resolved optical gating (FROG) to characterize mode-locked lasers producing ultrashort pulses suitable for high-capacity optical communications systems at wavelengths around 1550 nm was discussed.
Abstract: This paper reviews the use of frequency-resolved optical gating (FROG) to characterize mode-locked lasers producing ultrashort pulses suitable for high-capacity optical communications systems at wavelengths around 1550 nm, Second harmonic generation (SHG) FROG is used to characterize pulses from a passively mode-locked erbium-doped fiber laser, and both single-mode and dual-mode gain-switched semiconductor lasers. The compression of gain-switched pulses in dispersion compensating fiber is also studied using SHG-FROG, allowing optimal compression conditions to be determined without a priori assumptions about pulse characteristics. We also describe a fiber-based FROG geometry exploiting cross-phase modulation and show that it is ideally suited to pulse characterization at optical communications wavelengths. This technique has been used to characterize picosecond pulses with energy as low as 24 pJ, giving results in excellent agreement with SHG-FROG characterization, and without any temporal ambiguity in the retrieved pulse.
TL;DR: It is shown that the second- and third-order dispersions of the continuum fiber and self-phase modulation are primarily responsible for the continuum generation and spectral shaping and close agreement between simulations and experiments is found.
Abstract: By propagating 500-fs pulses through 2.5 m of standard fiber followed by 2 m of dispersion-shifted fiber, we generated >200 nm of spectral continuum between 1430 and 1630 nm, which is flat to less than ±0.5 dB over more than 60 nm. Pulses obtained by filtering the continuum show no increase in timing jitter over the source laser and are pedestal free to >28 dB, indicating excellent stability and coherence. We show that the second- and third-order dispersions of the continuum fiber and self-phase modulation are primarily responsible for the continuum generation and spectral shaping and found close agreement between simulations and experiments.
TL;DR: In this article, single-mode optical fibers were tapered and then cleaved by ion beam milling to allow direct examination of the mode evolution in the taper with a microscope objective and CCD camera.
Abstract: Step-index single-mode optical fibers were tapered and then cleaved by ion beam milling to allow direct examination of the mode evolution in the taper with a microscope objective and CCD camera. Observation of HE/sub 1m/ modes is reported in tapered fibers cleaved at diameters ranging from 8 to 35 /spl mu/m. Theoretical scalar mode fields are fit to the experimental data and the mode transitions are explained by considering coupled mode theory.
TL;DR: It is concluded that, for any optical fiber that does not experience polarization-dependent gain or loss, there exist two orientations for linearly polarized light input into the optical Fiber that will also exit the fiber linearly polarization.
Abstract: A simple theoretical formalism is developed to describe the effect of transmission on linearly polarized light through a fiber with random fluctuations of birefringence. We conclude that, for any optical fiber that does not experience polarization-dependent gain or loss, there exist two orientations for linearly polarized light input into the optical fiber that will also exit the fiber linearly polarized. We report experimental results that verify this prediction and also investigate its practical implications and limitations; in particular we investigate the stability of these linearly polarized output states in laboratory conditions.
TL;DR: In this article, the authors consider travelling periodic and quasiperiodic wave solutions of a set of coupled nonlinear Schrodimger equations, which describe pulse-pulse interaction in wavelength-division-multiplexed channels of optical fiber transmission systems.
Abstract: We consider travelling periodic and quasiperiodic wave solutions of a set of coupled nonlinear Schr\"odimger equations. In fibre optics these equations can be used to model single mode fibers with strong birefringence and two-mode optical fibres. Recently these equations appear as modes, which describe pulse-pulse interaction in wavelength-division-multiplexed channels of optical fiber transmission systems. Two phase quasi-periodic solutions for integrable Manakov system are given in tems of two-dimensional Kleinian functions. The reduction of quasi-periodic solutions to elliptic functions is dicussed. New solutions in terms of generalized Hermite polynomilas, which are associated with two-gap Treibich-Verdier potentials are found.
TL;DR: In this paper, the amplitude evolution of the backscattered field passed through a linear polarizer, aligned with the state of polarization of the input signal, has been studied and the mean value of the beat length can be calculated using two methods based on a level crossing rate analysis of the signal and on the evaluation of the standard deviation of its spectral density.
Abstract: This paper presents analytical and numerical results on the statistical properties of the backscattering signal of a randomly perturbed, linearly birefringent, single-mode fiber. Our theory is based on the study of amplitude evolution of the backscattered field passed through a linear polarizer, aligned with the state of polarization of the input signal. In particular, we show that the mean value of the beat length can be calculated using two methods based, respectively, on a level crossing rate analysis of the backscattered signal and on the evaluation of the standard deviation of its spectral density.
01 Jan 1999
TL;DR: In this paper, a novel electrostatically actuated 2/spl times/2 fiber optic switch with very low operating voltage is presented, where a vertical mirror is raised above the substrate.
Abstract: In this paper, a novel electrostatically actuated 2/spl times/2 fiber optic switch with very low operating voltage is presented. Using stress-induced bending of polysilicon plates, a vertical mirror is raised above the substrate. Electrostatic force is used to attract the mirror to the substrate to switch between the cross and the parallel states of the optical switch. The stress-induced curvature of the polysilicon beam substantially lowers the operating voltage of the switch. Large mirror displacement (300 /spl mu/m) and low operating voltage (20 V) are achieved simultaneously. Sub-millisecond switching time ( 14 million cycles) have been demonstrated. The insertion loss is measured to be 0.55 dB and 0.7 dB for single mode fibers in the cross and parallel states, respectively.
TL;DR: In this article, the authors proposed an integrated optical isolator independent of light polarization, which can be realized on structures with magnetization tangential to the propagation direction, and three geometries of non-reciprocal phase shifters are discussed and tolerances are estimated.
Abstract: This paper proposes, for the first time, an integrated optical isolator independent of light polarization. A Mach-Zehnder interferometer (MZI) with two nonreciprocal phase shifters, one for transverse electric (TE) modes and another one for transverse magnetic (TM) modes can be adjusted so that it blocks the fundamental modes of the waveguides constituting the interferometer propagating in one direction and is transparent for the modes propagating in the opposite direction. If the interferometer branch waveguides are in single mode regime, the performance of the device will not depend on the polarization of incoming light. The nonreciprocal phase shifters can be realized on structures with magnetization tangential to the propagation direction. Three geometries of nonreciprocal phase shifters are discussed and tolerances are estimated.