William Angerer - Department of Physics and Astronomy - University ...

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I 59 E c ........... .£: 950 900 (J'\ 850 c Q) Q) > 0 3: ~ 800[ 7SJ I 4.4 4.6 4.8 5.0 5.2 BRF Position (em) 5.4 1 i 1 -l I -1 I l I ~ I ..J i 1 l ~ I -1 I ..J ~ I I Figure 3.5: Ti:AI 2 0 3 wavelength as a function of birefringent filter position. Data is for the mid wavelength (MW) optics set. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
60 The production of ultrafast, high peak power pulses in the Ti:Ah03 laser occurs through a passive modelocking process called Kerr-lens modelocking. The cw laser light in the laser cavity is composed of a spectrum of frequencies. The width of this spectrum is determined by the active medium and the optics in the laser cavity. These frequencies, or longitudinal modes, are discrete as a result of the boundary conditions at the high reflector and output coupler mirrors. The modes are separated by a frequency '!rei L, where L is the length of the cavity. vVhen the laser is operating in cw mode, the phases between the modes are random. vVe can add a mechanism to the laser cavity that favors the propagation of a pulsed laser source as opposed to a cw source. The cw laser source will evolve to a pulsed laser source due to the gain differential between the two modes. This transformation from cw to pulsed mode occurs by fixing or locking the phase relationships between the modes to non-random values. In other words, by defining phase relationships, the longitudinal modes can add together to form a high intensity laser pulse. For the Ti:AI 2 0 3 laser, the laser crystal not only functions as the acti\·e medium. but also as a Kerr lens, i.e. the active medium has an intensity dependent index of refraction that is exploited to produce ultrafast pulses. By placing a partially closed shutter in front of the output coupler, a loss is added to the cavity. If a noise spike. i.e. an intense pulse of light, is introduced into the cavity, the higher intensity of the spike will activate the Kerr lens modelocking and the light associated with the noise spike Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
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SHG SPECTROSCOPY OF GALLIUM NITRIDE
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COPYRIGHT vVilliam E. Angerer 1998
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ACKNOWLEDGEMENTS I am most grateful
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vi and support over the last three
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viii and we report on photoluminesc
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x 2.5 ~ovel Technique and Apparatus
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Xll 7.3 7.2.3 Registering and Posit
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xiv
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xvi 2.10 Device for measuring ultra
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xviii 6.5 Polarization and propagat
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2 scopies as a probe of these featu
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4 tionallinear microscopy is unable
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6 interference by group velocity mi
Page 27 and 28: Chapter 2 Introduction to Nonlinear
Page 29 and 30: 10 the electric fields as In this t
Page 31 and 32: 12 SHG is a virtual process, Le. th
Page 33 and 34: 14 2.3 (2) Xijk and Symmetry In gen
Page 35 and 36: 16 X (2) zxx = ,\.zyy v(2) (2) = v(
Page 37 and 38: 18 X~}k(W = 2wo) of our GaN samples
Page 39 and 40: 20 nonlinear element of quartz, X~~
Page 41 and 42: 22 the transmitted wave, E:t'°, Th
Page 43 and 44: 24 150 I I "1 I :) ~ >- -. iii c v
Page 45 and 46: 26 Quartz fundamental Figure 2.5: I
Page 47 and 48: 28 The bound wave, which propagates
Page 49 and 50: 30 1/e 2 its ma.'{imum value. This
Page 51 and 52: 32 Here, x~;!Aw = 2wo) is a constan
Page 53 and 54: 34 simplifications (2.39) and (2.40
Page 55 and 56: 36 nonlinear waves. This model assu
Page 57 and 58: 38 Fourier transform to E /2 (r, w)
Page 59 and 60: 40 3 mm and with the parameters dis
Page 61 and 62: 42 I " i iii iii iii iii iii iii ii
Page 63 and 64: 44 parameter value Bl 2.35728 B2 -0
Page 65 and 66: 46 is measured as a function of tra
Page 67 and 68: 48 send pulse into device \11 input
Page 69 and 70: 50 2.6 Conclusion In this brief sec
Page 71 and 72: 52 LOCK-IN AMPLIAER LOCK-IN AMPLIAE
Page 73 and 74: 54 After polarization, the beam was
Page 75 and 76: 56 PO HR !l o IV team BP Figure 3.3
Page 77: 58 .. ........... • / ~ '" ~ r --
Page 81 and 82: 62 800 ~ 0 0 J 0 0 0 0 J ~ 0 600~ 0
Page 83 and 84: 64 measurements. Typically, I incre
Page 85 and 86: 66 described below. Note that laser
Page 87 and 88: 68 sentiallya nonlinear optical int
Page 89 and 90: 70 780 800 820 840 860 880 900 920
Page 91 and 92: 72 Unlike the linear spectroscopic
Page 93 and 94: 74 fore, the ratio of these two qua
Page 95 and 96: 76 of :UN is deposited on the Ah03
Page 97 and 98: 78 computer HeNe Las polarizer chop
Page 99 and 100: 80 ~------".... GaN A12a3 index flu
Page 101 and 102: 82 + d I , GaN A12a3 Figure 4.3: Co
Page 103 and 104: 84 4.2 Measurement of Indices of Re
Page 105 and 106: 86 fields at the lh interface to th
Page 107 and 108: 88 traveling wave, i.e. (-1.7) wher
Page 109 and 110: 90 Note that the additional subscri
Page 111 and 112: 92 £b, are defined only at the int
Page 113 and 114: 94 Equations (4.30) and (4.32) are
Page 115 and 116: 96 the calculation of the transmitt
Page 117 and 118: 98 '- -0 OJ N 0.4 o E ~ o Z 0.2 o 2
Page 119 and 120: 100 2.0 "'"" "I 1.5 E ::t ~ --c 0 -
Page 121 and 122: 102 4.3 Photoluminescence of GaN To
Page 123 and 124: 104 a photoluminescence measurement
Page 125 and 126: 106 :J 0.01 0 ~ L ~ 0.008 r- :n :v
Page 127 and 128: 108 0.08 ~. j -i ,-... I I ""I :::l
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Chapter 5 Properties of GaN In rece
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112 5.1 Crystal Structure :\ crucia
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114 PJO'tI [{fall Figure 5.1: \Vurz
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116 e 4 r .1 It Figure 5.2: Calcula
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118 Parameter Symbol Value electron
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120 high intrinsic electron concent
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122 equation (5.2), is represented
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124 C6v E E £l. 2C3 2C 3 2C6 2C 6
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126 gap, the nonlinear susceptibili
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128 rrb 10.0 eV -------- 5 9.0 eV r
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130 In> 1m> 1m>
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132 Emission of a photon on the bra
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134 5.5 MOCVD Growth of GaN Our GaN
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136 # dopant thickness mobility car
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138 6.1 Nonlinear Optical Spectrosc
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140 y lab X)lSlaJ / 2m Figure 6.1:
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142 Fig. 6.2 displays the azimuthal
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144 includes the effects of pulse p
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146 6.3 Theory of Nonlinear Optical
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148 L x i d 1 E( 00) air GaN sapphi
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150 wavevector components. The free
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152 z y x E( ro) air GaN Figure 6.5
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154 various free waves and summing
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156 factors are: the nonlinearity o
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158 where v /2 is the group velocit
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160 i N -' '- 0 ::J a 0 o.sf fiftH!
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162 4 ""' ::J en Q) - -' .D 2L ·oJ
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164 approximation. The agreement be
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166 midgap state) could playa role
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168 r: b S ~ r b I rs ~ r b I 0)1 r
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170 in various bonding geometries w
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, 172 .----. ::l U'J Q) ttl 0 '-.,;
Page 193 and 194:
Chapter 7 SHG Microscopy The majori
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176 7.1 Historical Context of Secon
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178 comPJter - - - - - - - - - ~ ,-
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180 second-harmonic light towards t
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182 ~ 20 _____ ~ ____ J -----f- ---
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184 wave at normal incidence is (7.
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186 polarization is negligible for
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chopper AGate B Gate Signal Figure
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190 E 4000 1 c: 0 3000 ~ rJl -' 0 c
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192 depend on two components: a hig
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194 nanorope ~ Figure 7.8: Carbon n
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196 of light reflected from the sam
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198 mean square deviation, of the p
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200 7.3 Calculated SHG Signal from
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202 parameter symbol value laser re
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204 parameter symbol value surface
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Chapter 8 Conclusion In this brief
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208 properties of carbon nanotubes.
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210 that propagate through quartz a
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Appendix B Theory of Nonlinear Resp
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214 Fourier transforming equation (
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216 and (CA) with f.b == t(.:.vo) a
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218 The polarization, et, of the po
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220 and (0.1.,1) respectively. Equa
Page 241 and 242:
Appendix E Effect of Sapphire Miscu
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224 with cosO 0 - sin (} o 1 o (E.3
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226 Let us compare the light transm
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228 , .............................
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230 it ( (fp·top..,(arr (ll, M r "
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232 nal-2.00 tab'(:r[ihi]-:r[ila] )
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234 1 - 2500.0; III - xU]; 1/ ti. t
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Bibliography [1] R. K. Chang~ J. Du
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238 [12] J. QL "V. Angerer, M. S. Y
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240 Diamond, SiC and Wide Bandgap S
Page 261 and 262:
242 [40] M. M. Choy and R. L. Byer,
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244 [55] \V. P. Lin, P. M. Lundquis
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246 [70] J. vV. Yang, J. N. Kunzia,
Page 267 and 268:
248 [85] B. Monemar and O. Lagerste
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250 [99] R. C. Miller, Optical Seco
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252 [114] "V. de HeeL W. S. Bacsa,
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William Angerer - Department of Physics and Astronomy - University ...

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