Optical properties of photonic crystals - New Jersey Institute of ...

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CHAPTER 2 BACKGROUND AND SIGNIFICANCE OF STUDIES ON PHOTONIC CRYSTALS Photonic crystals are periodic structures that, through interference, prevent certain electromagnetic waves from propagating through the structure. The crystals are of interest to designers of optoelectronic devices since they efficiently confine energy in a desired wavelength region. Because crystal structures must be built at the same scale as the wavelength to be suppressed, the difficulty of producing photonic crystals increases with higher frequencies. As a result, most successful demonstrations of the principle have used millimeter and microwaves. Photonic Crystals present a tremendous opportunity for the future; they reduce the mass of a system, increase the efficiency and are simple to manufacture all features that are essentially antenna systems. Photonic crystals are structures that restrict the propagation of particular wavelengths of light through destructive interference. These forbidden wavelengths, as in electronics, are defined as being within the bandgap of the structure and the crystals are often also known as photonic bandgap materials. According to an article in the Nature, a few developments could mark an important advancement in the field and could lead to applications such as ultrafast optical switching, guiding light on a semiconductor chip and constructing efficient microlasers. These photonic crystals, which measure less than half a micron, are different from other photonic crystals in several respects. Bragg gratings, for example, are one-dimensional and have a larger cavity. The size of the microcavity inside the three-dimensional crystals is much smaller, making them suitable for highly efficient nanolasers. By introducing 12
13 doping elements, physicists increase the density of electromagnetic states within the crystal at one specific frequency. At that frequency, the atoms inside the crystal will undergo a faster spontaneous emission (or faster rate of recombination). When atoms undergo this transition, photons will bounce back and forth against the crystal walls, which function like mirrors. A fraction of the light then escapes from the crystal. 2.1 Properties of Photonic Band Gap Materials Since the invention of the laser, the field of photonics has progressed through the development of engineered materials, which mold the flow of light¹³. Photonic band gap (PBG) materials are a new class of dielectrics, which are the photonic analogues of semiconductors. The photonic band gap is equivalent to a frequency interval over which the linear electromagnetic propagation effects have been turned off Unlike semiconductors, which facilitate the coherent propagation of electrons, PBG materials facilitate the coherent localization of photons^14. Applications include zero-threshold micro-lasers with high modulation speed and low threshold optical switches and alloptical transistors for optical telecommunications and high-speed optical computers. In a PBG, lasing can occur with zero pumping threshold. Lasing can also occur without mirrors and without a cavity mode since each atom creates its own localized photon mode. This suggests that large arrays of nearly lossless microlasers for all optical circuits can be fabricated with PBG materials. Near a photonic band edge, the photon density of states exhibits singularities, which cause collective light emission to take place at a much faster rate than in ordinary vacuum. Microlasers operating near a photonic band edge will exhibit ultrafast modulation and switching speeds for application in high-speed data
Page 1 and 2: Copyright Warning & Restrictions Th
Page 3 and 4: ABSTRACT BAND -GAP CHARACTERISTICS
Page 6 and 7: APPROVAL PAGE OPTICAL PROPERTIES OF
Page 8 and 9: This Thesis is dedicated to my fami
Page 10 and 11: TABLE OF CONTENTS Chapter Page 1 IN
Page 12 and 13: TABLE OF CONTENTS (Continued) Chapt
Page 14 and 15: LIST OF FIGURES Figure Page 1.1 Str
Page 16 and 17: LIST OF FIGURES (Continued) Figure
Page 18 and 19: 2 The friction between the photonic
Page 20 and 21: 4 progress towards all-optical inte
Page 22 and 23: As can be seen in Figure 1.2, with
Page 24 and 25: 8 1.1.2 Two Dimensional Photonic Cr
Page 26 and 27: 10 future. They may provide a novel
Page 30 and 31: 14 transfer and computing. Applicat
Page 32 and 33: 16 Chigrin and Lavrinenko in collab
Page 34 and 35: 18 component of the wave vector rem
Page 36 and 37: 20 2.2.1 Transfer Matrix Method The
Page 38 and 39: Figure 2-3 Structure of a 2D photon
Page 40 and 41: 24 enhancing the efficiency of lase
Page 42 and 43: 26 Figure 2-6 A perfect waveguide i
Page 44 and 45: CHAPTER 3 FUNDAMENTALS OF OPTICAL P
Page 46 and 47: 30 the square of its amplitude--i.e
Page 48 and 49: 32 3.2 Control of Properties of Mat
Page 50 and 51: 34 Figure 3.3 Spontaneous-emission
Page 52 and 53: 36 current it generated. But the fi
Page 54 and 55: 38 be used in a solar cell, generat
Page 56 and 57: 40 4.1.3 Spectral Range The spectra
Page 58 and 59: 42 beyond the scope of MultiRad. Th
Page 60 and 61: 44 c. It considers only Silicon as
Page 62 and 63: Figure 5.1 Schematic of bench top e
Page 64 and 65: 48 radiative properties of interest
Page 66 and 67: 50 The final structure of the 3D cr
Page 68 and 69: 52 The wafers are then planarized b
Page 70 and 71: 54 Fig 6.2 Block diagram showing di
Page 72 and 73: 56 decreases to a minimum in a cert
Page 74 and 75: 58 only be carried in one dimension
Page 76 and 77: Figure 6.9 Simulated transmission t
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62 Fig 6.10 Transmission spectra fo
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64 Figure 6.11(b) Transmission spec
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66 As can be seen from the above ta
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Fig 6.14 Simulated reflectance spec
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Fig 6.16 Simulated transmittance sp
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72 7.2 Recommendations Much of the
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1.4 54.9 58.3 44.6 64.1 1.5 62.4 70
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11.2 60.3 64 53.8 48.2 11.3 59.7 62
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APPENDIX A2 RAW DATA This appendix
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APPENDIX A2 (CONTINUED) 80 0.232 5.
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APPENDIX A2 (CONTINUED) 8Z 0.221 2.
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BIBLIOGRAPHY [1] E. Yablonovitch, "
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96 [25] G. E. Jellison, F. A. Modin
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