A Wavelength Converter Integrated with a Discretely Tunable Laser ...

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40 4. Integration of waveguide components on InP Fast (sub nano-second) phase modulators. Efficient fiber-chip coupling. An additional requirement is, of course, that the fabrication process of all the components is compatible during the epitaxy and the waveguide etching. Before discussing the waveguide components in more detail, the next sections outlines the properties of the InGaAsP/InP material system, in which the waveguides are fabricated. passive low contrast high contrast Straight waveguide Curved waveguide PHASAR Straight waveguide Curved waveguide PHASAR passive + phase shifters passive+ SOAs Phase shifter Modulator Switch Cross connect Optical amplifier Multi−wavelength laser Wavelength converter Figure 4.1: Examples of waveguide components that can be fabricated using PWDs, SOAs and PHMs. 4.2 Properties of the InGaAsP/InP material system The III-V semiconductor material system InGaAsP/InP is well suited for the fabrication of photonic devices that have to operate at the 1.3 window or the 1.55 window used in optical fiber communication. This thesis is dedicated to devices in the 1.55 window. In optical chips on InGaAsP/InP, the light is confined in a bulk layer of the quaternary compound ¨ ¦ ¨ . The compound is grown on an InP substrate and cladded with InP. The bulk material should be lattice matched to InP to avoid lattice defects. For the lattice matched compound, the relation between the Ga fraction and the As fraction is [67] Using this equation, the properties of the compound can be expressed in the As fraction , as shown in table 4.1. The bandgap wavelength of the lattice matched ¨ can ¨ ¤ ¤ (4.1) ¨ ( ¤ ( ¤ be tuned between 0.92 ) and 1.65 ). Quaternary material that is lattice matched to InP will be denoted as , where , and where denotes the bandgap energy in eV.
4.3 Waveguide components 41 Table 4.1: Shown are several material properties of ¢ ¢ lattice matched to InP. The properties are expressed in the As fraction . is the elementary electron mass. electron [ mass ¨ ¤ ¦ ] heavy hole [ mass ¨ ¤ ¦ ] light hole [ mass ¤ ¦ ] bandgap energy ¤ ¤ ¦ [eV] real refractive index ¤¨¨ ¤ ¤ at 4.3 Waveguide components This section provides an overview of the geometry and features of the three types of waveguide components in the PICs: passive waveguides, SOAs, and phase modulators. A more quantitative description of the optimization of the components can be found in Sec. 4.4. 4.3.1 Passive waveguides Passive waveguides can be employed as interconnecting waveguides between the different components on a chip, or for the construction of passive components like (de-)multiplexers and power couplers. Most important requirements for passive waveguides are low propagation loss, mono mode behavior, suitability for small radii of curvature, and polarization independence. A typical ridge waveguide is shown in Fig. 4.2a. It consists of a (film) layer of quaternary material that is embedded between two InP layers. Confinement of the light in the transverse direction is provided by the higher refractive index of the film layer with respect to the InP layers. The index of the film, for different compositions, is calculated according to Suematsu [68]. At a wavelength of ¤ ¨¨ the indices lie between for Q(1.00) and for Q(1.40). The refractive index of InP is ¤ . Confinement in the lateral direction is realized by etching a ridge structure (Fig. 4.2a). The ridge waveguide is etched partly into the film layer and it is referred to as a shallowly-etched waveguide. Only a discrete number of w opticall field InP Q( λg) film InP t f = 500 nm w optical field a) shallow b) deep c) shallow−deep transition Figure 4.2: Illustration of the cross sections of a) a shallowly-etched passive waveguide and b) a deeply-etched waveguide. c) A Transition between shallowly and deeply etched waveguides.
Page 1 and 2: A Wavelength Converter Integrated w
Page 3 and 4: iii
Page 5 and 6: Contents v 4.3 Waveguide components
Page 7 and 8: Chapter 1 Introduction 1.1 Optical
Page 9 and 10: 1.2 Exploiting optical fiber capaci
Page 11 and 12: 1.3 Wavelength conversion in WDM ne
Page 13 and 14: Chapter 2 Wavelength converter over
Page 15 and 16: 2.2 Optical gating 9 λcontrol λpr
Page 17 and 18: 2.2 Optical gating 11 powers (in th
Page 19 and 20: 2.2 Optical gating 13 Michelson Int
Page 21 and 22: 2.3 Coherent wave mixing (FWM, DFG)
Page 23 and 24: 2.5 Summary 17 2.5 Summary The main
Page 25 and 26: Chapter 3 Semiconductor optical amp
Page 27 and 28: 3.2 Amplification in SOAs 21 Table
Page 29 and 30: 3.3 Extended Cavity Lasers and exte
Page 45: Chapter 4 Integration of waveguide
Page 49 and 50: 4.3 Waveguide components 43 4.3.2 P
Page 51 and 52: 4.4 Integration trade-offs 45 the a
Page 53 and 54: 4.4 Integration trade-offs 47 The c
Page 55 and 56: 4.4 Integration trade-offs 49 speed
Page 57 and 58: 4.4 Integration trade-offs 51 resis
Page 59 and 60: 4.4 Integration trade-offs 53 activ
Page 61 and 62: 4.4 Integration trade-offs 55 a) 60
Page 63 and 64: 4.4 Integration trade-offs 57 due t
Page 65 and 66: 4.4 Integration trade-offs 59 The
Page 67 and 68: 4.5 Conclusions 61 4.5 Conclusions
Page 69 and 70: Chapter 5 Technology 5.1 Introducti
Page 71 and 72: 5.2 Epitaxy 65 of the stack Q(1.25)
Page 73 and 74: 5.3 Waveguide processing 67 InP Q(1
Page 75 and 76: 5.3 Waveguide processing 69 h l h S
Page 77 and 78: 5.4 Contact openings and metalizati
Page 79 and 80: 5.4 Contact openings and metalizati
Page 81 and 82: Chapter 6 MWL with absolute wavelen
Page 83 and 84: 6.3 MWL with absolute wavelength co
Page 85 and 86: 6.3 MWL with absolute wavelength co
Page 87 and 88: 6.5 Measurements 81 facet M 1 O4 O3
Page 89 and 90: 6.5 Measurements 83 127 mA, which e
Page 91 and 92: Chapter 7 MZI wavelength converter
Page 93 and 94: 7.2 Operating principle of the MZI
Page 95 and 96: 7.3 Converter performance 89 Note t
Page 97 and 98:
7.3 Converter performance 91 Chirp
Page 99 and 100:
7.4 Wavelength converter design 93
Page 101 and 102:
7.5 Fabrication 95 1 2 3 4 5 6 7 8
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7.6 Measurements 97 Power out [dBm]
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7.6 Measurements 99 mental and firs
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7.6 Measurements 101 fiber-to-fiber
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7.6 Measurements 103 P out [dBm] P
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7.6 Measurements 105 Power [dBm] -1
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7.6 Measurements 107 Substituting E
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7.6 Measurements 109 7.6.4 BER meas
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7.7 Conclusion 111 output extinctio
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Chapter 8 Wavelength Converter inte
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8.2 Design 115 MWL1 M1 O1 O2 O3 O4
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8.4 Static measurements 117 Control
Page 125 and 126:
8.4 Static measurements 119 The LI-
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8.5 Dynamic operation 121 BER 2.5 G
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8.6 Discussion 123 Wavelength [μm]
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8.6 Discussion 125 lower then the l
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8.7 Conclusions 127 8.7 Conclusions
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Appendix A Mask plates The mask pla
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References [1] H. Takara, E. Yamada
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References 133 [24] R.G. Broeke, J.
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References 135 [51] C.Q. Xu, K. Shi
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References 137 [88] J.J.M. Binsma,
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Summary A wavelength converter inte
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Samenvatting Een golflengte omzette
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Dankwoord Een dankwoord hoort vol m
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echoduo een glas komen claimen, en
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List of Abbreviations AOWC All Opti
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Curriculum Vitae Ronald Broeke was
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List of publications 1. R.G. Broeke
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18. R.G. Broeke A Chirped phased-ar
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