WO2001053881A1 - Modulateur a resonance amelioree (rem) - Google Patents

Modulateur a resonance amelioree (rem) Download PDF

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Publication number
WO2001053881A1
WO2001053881A1 PCT/US2001/002070 US0102070W WO0153881A1 WO 2001053881 A1 WO2001053881 A1 WO 2001053881A1 US 0102070 W US0102070 W US 0102070W WO 0153881 A1 WO0153881 A1 WO 0153881A1
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WIPO (PCT)
Prior art keywords
modulator
resonant
coupled
ring
electro
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Application number
PCT/US2001/002070
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English (en)
Inventor
Joseph H. Abeles
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Princeton Lightwave, Inc.
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Application filed by Princeton Lightwave, Inc. filed Critical Princeton Lightwave, Inc.
Priority to AU2001241424A priority Critical patent/AU2001241424A1/en
Priority to US10/181,540 priority patent/US6744548B2/en
Publication of WO2001053881A1 publication Critical patent/WO2001053881A1/fr

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S5/00—Semiconductor lasers
    • H01S5/10—Construction or shape of the optical resonator, e.g. extended or external cavity, coupled cavities, bent-guide, varying width, thickness or composition of the active region
    • H01S5/12—Construction or shape of the optical resonator, e.g. extended or external cavity, coupled cavities, bent-guide, varying width, thickness or composition of the active region the resonator having a periodic structure, e.g. in distributed feedback [DFB] lasers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q23/00—Antennas with active circuits or circuit elements integrated within them or attached to them
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/21—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  by interference
    • G02F1/225—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  by interference in an optical waveguide structure
    • G02F1/2257—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  by interference in an optical waveguide structure the optical waveguides being made of semiconducting material
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/29—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the position or the direction of light beams, i.e. deflection
    • G02F1/31—Digital deflection, i.e. optical switching
    • G02F1/313—Digital deflection, i.e. optical switching in an optical waveguide structure
    • G02F1/3132—Digital deflection, i.e. optical switching in an optical waveguide structure of directional coupler type
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/29—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the position or the direction of light beams, i.e. deflection
    • G02F1/31—Digital deflection, i.e. optical switching
    • G02F1/313—Digital deflection, i.e. optical switching in an optical waveguide structure
    • G02F1/3137—Digital deflection, i.e. optical switching in an optical waveguide structure with intersecting or branching waveguides, e.g. X-switches and Y-junctions
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q3/00—Arrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system
    • H01Q3/26—Arrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system varying the relative phase or relative amplitude of energisation between two or more active radiating elements; varying the distribution of energy across a radiating aperture
    • H01Q3/2682—Time delay steered arrays
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/011—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  in optical waveguides, not otherwise provided for in this subclass
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/21—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  by interference
    • G02F1/212—Mach-Zehnder type
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/21—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  by interference
    • G02F1/225—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  by interference in an optical waveguide structure
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F2201/00—Constructional arrangements not provided for in groups G02F1/00 - G02F7/00
    • G02F2201/16—Constructional arrangements not provided for in groups G02F1/00 - G02F7/00 series; tandem
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F2203/00—Function characteristic
    • G02F2203/05—Function characteristic wavelength dependent
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F2203/00—Function characteristic
    • G02F2203/15—Function characteristic involving resonance effects, e.g. resonantly enhanced interaction
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F2203/00—Function characteristic
    • G02F2203/58—Multi-wavelength, e.g. operation of the device at a plurality of wavelengths
    • G02F2203/585—Add/drop devices
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S5/00—Semiconductor lasers
    • H01S5/10—Construction or shape of the optical resonator, e.g. extended or external cavity, coupled cavities, bent-guide, varying width, thickness or composition of the active region
    • H01S5/1039—Details on the cavity length
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S5/00—Semiconductor lasers
    • H01S5/20—Structure or shape of the semiconductor body to guide the optical wave ; Confining structures perpendicular to the optical axis, e.g. index or gain guiding, stripe geometry, broad area lasers, gain tailoring, transverse or lateral reflectors, special cladding structures, MQW barrier reflection layers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S5/00—Semiconductor lasers
    • H01S5/20—Structure or shape of the semiconductor body to guide the optical wave ; Confining structures perpendicular to the optical axis, e.g. index or gain guiding, stripe geometry, broad area lasers, gain tailoring, transverse or lateral reflectors, special cladding structures, MQW barrier reflection layers
    • H01S5/2036—Broad area lasers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S5/00—Semiconductor lasers
    • H01S5/30—Structure or shape of the active region; Materials used for the active region
    • H01S5/32—Structure or shape of the active region; Materials used for the active region comprising PN junctions, e.g. hetero- or double- heterostructures
    • H01S5/323—Structure or shape of the active region; Materials used for the active region comprising PN junctions, e.g. hetero- or double- heterostructures in AIIIBV compounds, e.g. AlGaAs-laser, InP-based laser

Definitions

  • the present invention relates generally to digital communications and networking technologies and analog technologies such as radar and particularly to modulator components therefor.
  • a modulator including: a plurality of branches; first and second RF electrodes; a first plurality of RF delay elements coupled to the first RF electrode and a second plurality of RF delay elements coupled to the second electrode; and, a plurality of electro-optic resonant elements each being respectively coupled for RF frequency energy exchange with a corresponding one of the RF delay elements and coupled for optical frequency electromagnetic energy exchange to at least one of the branches.
  • FIG. 1 illustrates a Resonant Enhanced Modulator (REM) according to an aspect of the present invention
  • Figure 2 illustrates a general dual-coupled electro-optic resonant optical element suitable for use in combination with the present invention and operational characteristics thereof;
  • Figure 3 illustrates a dual-coupled electro-optic ring resonant optical element suitable for use in combination with the present invention and operational characteristics thereof;
  • Figure 4 illustrates a side-by side comparison of electro-optic ring and conventional Mach-Zehnder modulators
  • Figure 5 illustrates a single- or side-coupled ring resonator incorproated within a Mach Zehnder modulator
  • Figure 6 illustrates a schematic of an electro-refractive Mach-Zehnder REM according to an aspect of the present invention
  • Figure 7 illustrates operation characteristics of the modulator of Figure 6;
  • Figure 8 illustrates operational characteristics of a resonant enhanced Mach-Zehnder modulator according to another aspect of the invention.
  • Figure 9 illustrates required material propagation losses for electro-refractive ring resonant elements of the modulator of Figure 6 according to an aspect of the invention
  • Figure 10 illustrates a schematic representation of an equivalent circuit of a matching network and REM according to another aspect of the invention
  • Figure 1 1 illustrates an achievable performance enhancement according to an aspect of the present invention.
  • Figure 12 illustrates a design layout of a combined antenna, matching network and REM device utilizing a microwave ridge waveguide to effect impedance transformation
  • Tenth-volt-class optical modulators are highly desirable for high speed digital modulation at speeds of, e.g., 40 Gb/s and higher, in order to reduce the requirement for power dissipation on the part of the drive electronics.
  • Tenth-volt-class optical modulators are essential for the remoting of systems integrator receive arrays if multi-kW dissipation
  • Micro-ring resonators of substantially 10 ⁇ m diameter or less enable a small
  • Arraying of multiple micro-ring resonators, in which each provides only a small portion of the overall modulation, can advantageously achieve significant reductions in voltage.
  • This strategy can be employed both for electro-absorptive (EA) and electro- refractive (ER) configurations.
  • ER configurations are superior at high optical powers as is necessary for low analog link noise figures.
  • the ER configuration allows shot-noise-limited (i.e., low-noise) transmission of the received antenna signal to a receive module.
  • series cascading of multiple ER resonant elements does not result in a narrowing of the pass bandwidth of the resonant elements, whereas series cascading of multiple EA resonant elements causes a progressive narrowing of the maximum bandwidth of the modulated signal passing through the circuit. Therefore, in the case of a cascade of EA resonant modulating elements, possible advantages associated with increased sensitivity are offset, at least in part, by a narrowing of bandwidth. The same narrowing does not occur for ER cascades. Therefore in the preferred embodiment of the present invention, a cascade of ER resonant elements is employed and EA behavior is eschewed.
  • a substantial advantage in modulator sensitivity is attained by exploiting multiple resonances.
  • the invention shall be described to include three separate resonances, which cause the maximum sensitivity to be obtained. However, one of these three resonances as shall be described causes the modulator to exhibit a peak in sensitivity at a microwave drive frequency. This is desirable for certain RF applications, such as radar applications mentioned above. However, for standard baseband digital telecommunications applications, it is not desirable that modulator response be peaked at any particular RF frequency. Therefore, there is a second desirable embodiment which inherently is more desirable for baseband applications, i.e., those for which modulation efficiency is desired to be equally high from near DC to the maximum frequency of operation.
  • V m denoting sensitivity of modulators
  • a 0.01-N-class X-band resonant enhanced modulator (REM) module demonstrating > 100 times reduction in modulation
  • Conventional modulators are singly- (semiconductor) or non- (Li ⁇ bO 3 ) resonant, whereas REMs of the first preferred embodiment exploit three resonances at: (a) the -200 THz bandgap; (b) a -2.7 THz resonator free-spectral-range; and (c) a 10 GHz frequency
  • the present invention builds
  • the design is based on: (1) low-loss 10-100 ⁇ m
  • Modulation efficiency is the primary limiting factor preventing deployment of compact advanced radar imaging systems.
  • Modulated capacitance C m is a primary factor limiting the efficiency of conventional EA modulators.
  • Resonant enhancement provides a dramatic reduction in C m compared to a single-pass modulator of equivalent bandwidth.
  • hybrid matching circuits 105, 110, 115 are used to match impedances and enhance voltage response over the system frequency band. With a 10 times capacitance reduction, and other benefits such as the relatively small size of the REM 120, the conventional -1 V requirement is advantageously lessened to -0.01 V.
  • REMs further exhibit resonance peaks widths that are closely related to modulation bandwidth. Larger resonators with narrower resonances and greater modulation efficiency exhibit longer photon lifetimes which limit modulation bandwidth.
  • the width of the resonance peak therefore, denotes the bandwidth of the modulated signal that can pass through the modulator in addition to the bandwidth of electro-optic modulation that can be achieved.
  • Electorefractive REMs such as that designated 305 can further advantageously be utilized.
  • Resonant enhancement demands propagation losses well below coupling; for a 5% coupler, ⁇ 1% (cf. Figure 3). Bending loss is negligible for deep-etched waveguides, mode mismatch is minimized by proper design and material loss is insignificant for small rings. Scattering must be minimized by smooth lithography. Mask edge and sidewall integrity degradation during etching should be minimized.
  • Modulation index per unit applied voltage can be optimized for a given bandwidth by permitting the optical wave to re-use a given electrode region on multiple passes.
  • Exploitation of the same basic strategy at a lower level of re-use has been reported employing a double-pass configuration by Oki Electric Industry, Tokyo, Japan. In this case a rather significant improvement in efficiency is realized at the cost of necessitating an optical circulator for a double-pass configuration.
  • dramatic improvements in efficiency are obtained from the application of a similar strategy, however a far superior vehicle of micro-optical ring resonators fabricated in, preferably, InP -based materials is used.
  • ring resonators as opposed to the more frequently used Fabry-Perot resonator, that input and output waves can be separated even at a single port of the resonator.
  • the resonant ring cavity allows a given electrode to be reused not merely twice, as in the Oki work, but 10 times if photons are trapped for, on average, 10 revolutions. Such is the case when coupling of less than 10% exists between the ring and
  • Tiny resonators of diameter 10 ⁇ m or smaller can be
  • the five sources of loss for ring resonators are: bending loss (minimized for high index contrast), scattering loss (dependent on the quality of fabrication), material loss (dependent on epitaxial design and the presence of carriers), and mode-matching loss (resulting from abrupt joints between dissimilar waveguides), and from the presence of continuum modes to which a guide mode may couple. All five sources of loss can be minimized by optimum design and fabrication techniques to obtain the high quality resonators described above.
  • the dwell time of photons within the modulating element also known as the photon lifetime, uniquely determines both bandwidth and phase shift for a given material structure regardless of whether the photons recycle through the same medium (as for a ring modulator) or visit a given region only once (as for a conventional straight waveguide modulator).
  • a key difference is that photons dwell longer in the ring resonator. Modulation bandwidth is determined by the characteristic dwell time. Therefore, the aforementioned reduction in drive voltage is obtained at a steep cost of reduction in bandwidth. Consequently there can be no advantage attained for a single resonator structure over a non- resonant modulator. This is a basic feature of such structures and derives from fundamental physical principles.
  • the advantage realized for the ring resonator is the reduced capacitance that is the basis of the approaches discussed herein.
  • the loading of drive circuitry is significantly lower for the resonant modulator, and capacitances of on the order of 0.01 pF or less are anticipated for a 10 gm diameter ring, as opposed to greater than 0.1 pF for conventional electro-absorption modulators.
  • a resonator 705 which induces a phase shift in a waveguide to which it is evanescently
  • a key feature of the configuration of Figure 5 is high return loss for light traveling in the side-coupled waveguide that makes up one arm of the Mach-Zehnder, and that this occurs in a configuration providing modulation of the index rather than of the absorption.
  • Index modulation is preferred for reasons including greater immunity to saturation, which is a particular issue for microresonators. This is because the optical intensity is multiplied 10- fold for a typical microresonator design, and because 10's of milliwatts or greater are desired to be modulated. Therefore, 100 mW power levels will circulate within the microresonator. Such powers may be inconsistent with unsaturated operation of intensity modulation.
  • the reactance associated with 0.01 pF amounts to 1500j ⁇ at 10 GHz
  • the complex modulation index for such a configuration in the side-coupled guide is:
  • Figure 7 shows the passband for such an electro-refractive Mach-Zehnder REM
  • the modulator of Figure 6 includes multiple branches or arms 802, 804. Each of the arms 802, 804 is connected to either a top or bottom RF electrode.
  • a plurality of RF delay elements (not shown) delay the propagation of electrical signals down the modulator to be substantially synchronized with optical signals propagating down the modulator.
  • Each of the resonant elements 806 are further evanescently coupled to one of the multiple branches, or arms 802, 804.
  • the electro-refractive Mach- Zehnder REM device of Figure 6 uses a coplanar type of microwave waveguide as a feed for multiple low-capacitive rings which are side-coupled to the waveguides of a Mach-Zehnder interferometer in waveguide form.
  • the delay elements encountered at each ring is compensated by delay of either a slow-wave transmission line structure, by a meander line or by lumped-element delays, for example.
  • the RF electrodes are configured in a push-pull configuration.
  • each ring modulator must allow for sufficient passband to permit the sidebands generated by modulation of the optical ca ⁇ ier to pass within the modulation band.
  • Figure 8 compares the average extinction over a 24 GHz bandwidth to that of a single- optical frequency versus applied voltage for two different ring diameters. It is not surprising
  • Losses are one of the key issues, and their minimization depends on proper design of the semiconductor material, proper device design, and proper selection of operation wavelength. It is to be anticipated that for wavelengths close to the quantum well bandgap there will be greater residual material losses tailing from the interband resonance. It is reasonable to anticipate that lower background losses will obtain where reversed biased junctions are employed and carriers are swept out. The residual interband absorption tailing can be minimized by careful heterostructure design, and choice of operating wavelength.
  • another strategy for counteracting loss is the introduction of a small amount of optical gain provided at a slightly shorter wavelength by the same optical fiber connection that carries the signal.
  • stabilization of the correct amount of gain is desirable because excessive gain is associated with na ⁇ owing of the resonance and would not support 4 GHz bandwidths.
  • An ER-REM Mach-Zehnder Modulator can modulate up to 20 mW. Only 6dB of loss is anticipated using smooth waveguide walls and mode expansion couplers. These modulators will be highly polarization-dependent to achieve minimum voltage. Temperature will can be stabilized using a conventional TE cooler arrangement.
  • Passive microwave matching circuitry is a key element for enhancement of the resonant enhanced modulator (REM) performance, as shown in Figure 1.
  • the low capacitance of a the REM permits a matching circuit to act as a transformer, stepping up the voltage to the REM electrodes owing to the minimal current drawn by the REM.
  • an equivalent circuit model 1200 is shown in Figure 10. Referring now also to Figure 11, it has been found that an 8 dB passive gain can be achieved.
  • a circuit layout is shown therein suitable for this equivalent circuit analysis employing waveguide for low loss and to achieve the transition from free space to the REM input. This represents the third resonance which is appropriate for non-base-band applications in the RF domain.

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  • Physics & Mathematics (AREA)
  • Nonlinear Science (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • Electromagnetism (AREA)
  • Semiconductor Lasers (AREA)
  • Optical Modulation, Optical Deflection, Nonlinear Optics, Optical Demodulation, Optical Logic Elements (AREA)
  • Optical Integrated Circuits (AREA)

Abstract

L'invention concerne un modulateur comprenant: une pluralité de branches (802, 804); une première et une seconde électrode RF; une première pluralité d'éléments de retard RF couplée à la première électrode RF et une seconde pluralité d'éléments de retard RF couplée à la seconde électrode; et, une pluralité d'éléments de résonance électro-réfractifs (806). Chaque élément de résonance électro-réfractifs (806) est respectivement couplé à un élément correspondant parmi les éléments de retard RF et couplé avec évanescence à au moins une des branches (802, 804).
PCT/US2001/002070 2000-01-20 2001-01-22 Modulateur a resonance amelioree (rem) WO2001053881A1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
AU2001241424A AU2001241424A1 (en) 2000-01-20 2001-01-22 Resonant enhanced modulator (rem)
US10/181,540 US6744548B2 (en) 2000-01-20 2001-01-22 Resonant enhanced modulator (REM)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US17691500P 2000-01-20 2000-01-20
US60/176,915 2000-01-20

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WO2001053881A1 true WO2001053881A1 (fr) 2001-07-26

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PCT/US2001/002070 WO2001053881A1 (fr) 2000-01-20 2001-01-22 Modulateur a resonance amelioree (rem)
PCT/US2001/002073 WO2001055814A2 (fr) 2000-01-20 2001-01-22 Commutateur a decoupage en canaux
PCT/US2001/002019 WO2001054240A1 (fr) 2000-01-20 2001-01-22 Laser de forte puissance, en guide d'ondes a arete a retroaction repartie

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PCT/US2001/002019 WO2001054240A1 (fr) 2000-01-20 2001-01-22 Laser de forte puissance, en guide d'ondes a arete a retroaction repartie

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US7903909B2 (en) 2007-10-22 2011-03-08 Massachusetts Institute Of Technology Low-loss bloch wave guiding in open structures and highly compact efficient waveguide-crossing arrays
US7920770B2 (en) 2008-05-01 2011-04-05 Massachusetts Institute Of Technology Reduction of substrate optical leakage in integrated photonic circuits through localized substrate removal
WO2010065710A1 (fr) * 2008-12-03 2010-06-10 Massachusetts Institute Of Technology Modulateurs optiques résonants

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US5291565A (en) * 1992-06-30 1994-03-01 Hughes Aircraft Company Broad band, low power electro-optic modulator apparatus and method with segmented electrodes
US6198854B1 (en) * 1998-08-25 2001-03-06 Mitsubishi Denki Kabushiki Kaisha Mach-Zehnder modulator

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AU2001262901A1 (en) 2001-08-07
EP1258065A4 (fr) 2006-08-30
WO2001055814A2 (fr) 2001-08-02
JP2003520455A (ja) 2003-07-02
AU2001247192A1 (en) 2001-07-31
EP1258065A1 (fr) 2002-11-20
CA2398833A1 (fr) 2001-07-26
WO2001054240A1 (fr) 2001-07-26
WO2001055814A3 (fr) 2002-02-07
AU2001241424A1 (en) 2001-07-31

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