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`Declaration
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`This dissertation contains the results of research undertaken by the author between October
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`1995 and December 1998 at the Engineering Department of Cambridge University. No part
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`of this dissertation is the result of work done in collaboration with others, except where
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`explicitly described or cited within the text. The contents have not been submitted, in whole
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`or in part, for any other University degree or diploma.
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`Kim Leong Tan
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`Cambridge, February 1999
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`To Sims
`To Sian
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`and
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`ourfamilies
`ourfimtifz’es
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`v
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`CONTENTS
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`viii
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`4.4.2 The replay of non-zero orders for phase-mismatched holograms ...................... 62
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`4.5 Conclusions ...... ...................... ...... ............ .......... ......... .............. .... ........................... ... 63
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`CHAPTERS
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`Applications of coupling intensity and discrete hologram replay descriptions
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`65
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`5 .1 Introduction ................................................................................................................. 65
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`5 .2 The design limitations of a large 1 :N holographic switch ............ .... ........ ..... .............. 65
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`5.2.1 On-beam-axis coupling efficiency and off-beam-axis crosstalk power. ............ 67
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`5.2.2 The number of hologram repeats for a l:N holographic switch ........................ 68
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`5.2.3 Prospective 1 :N switch using a highly specified SLM ... ..... ......... ..................... 72
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`5.3 Deterministic routing hologram generation ..................................................... ............ 75
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`5.3.1 1-D hologram generation by choosing a combination of x 0 phase elements ..... 76
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`5.3.2 Offsetting the 1-D combinations to provide 2-D routing patterns ..................... 78
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`5.3.3 The advantages of the skip-rotate hologram generation technique ............ ........ 79
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`5.4 Conclusions ................................................................................................................. 80
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`CHAPTER 6
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`FLC on CMOSNLSI Si spatial light modulators for holographic applications
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`81
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`6.1 Introduction ............................. ................. ... ..... .................. ............................ .... .... ..... 81
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`6.2 Polarisation rotation as a means of phase modulation ........ ....................................... . 82
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`6.2.1 Multi-level modulation .. ......... .. ................................. ... ..... ..... ......... ....... ... ..... ... 82
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`6.2.2 Binary modulation .............................................................................................. 86
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`6.3 Fast four-level phase-only modulation by polarisation rotation .................................. 88
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`6.3 .1 Analysis of enhanced switching using a double-pass configuration ... .. ... .. ....... 89
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`6.3 .2 Double-pass devices .. .......................... .......... ....... ............... ... .................... ... ..... 91
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`6.4 Processing digital data input for analogue devices ................................. ... ... ......... ..... 93
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`6.4.1 Global DA Cs .................. ........ .. .. ...... .. .................. ................. ............................. 94
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`6.4.2 Column-select DA Cs ......................................................................................... 95
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`6.4.3 Pixel-level DA Cs ............. ............................. .... ... .... ...... .... ..... ............ ......... .. .... 96
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`6.4.4 Choice of DAC location for the demonstrator chip ........................................... 98
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`6.5 Pixel design for coherent optical phase modulation ........ ... ...... ......... ...... ............... .... . 98
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`CONTENTS
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`ix
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`6.5.1 Enhanced optical reflectors for the binary SLM .. ... .... ....................................... 98
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`6.5.2 Transmissive pixels for quaternary SLM ........................................................... 99
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`6.6 Semiconductor fabrication process ................... .......................................................... 99
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`6.6.1 CBH lOV 2-µm CMOS process .... .. ... ............................................................. . 100
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`6.6.2 CBY 50V 2-µm DMOS process ...................................................................... 103
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`6.7 Conclusions ................................... .. ........................................... ........ ....... ................ 106
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`CHAPTER 7
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`Circuit design and layout of the Roses chip
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`108
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`7 .1 Introduction ..... ........................ .......................... ...... ................... ............. ... ... ............ 108
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`7 .2 Specifications for the binary and quaternary modulators .......... .... ........ .. .................. 109
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`7 .2.1 The reflective binary array .................................... ........ ................. ...... .... ........ 110
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`7.2.2 The transmissive quaternary array ...... .... ... ...................................................... 111
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`7 .3 Overall floor-plan ................................... ..... ........ ... ................................... ... ............. 111
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`7.4 Features and simulated performance of the Roses chip ............................................ 113
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`7 .5 Circuit design for binary modulation ..................................... ..... .............................. 116
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`7.5 .1 Binary driver schematics and functionality ..................................................... 116
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`7.5.2 Asynchronous global blanking ........ ........................................... ........... .......... . 118
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`7.5.3 Standard geometry MOSFET design .................. ............................ .......... ....... 118
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`7 .5 .4 Current-limiting in sizing level shifter transistors ........ ......... .......................... 118
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`7 .5 .5 Speed versus current-limiting trade-off in sizing buffering transistors ........... 118
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`7 .6 Layout of the binary backplane ............ ... ..... .. .. ..... ....................... .... .. ..... .................. 119
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`7 .6.1 Standard geometry MOSFET layout.. .............................................................. 119
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`7.6.2 Protecting supply lines from peak current effects .................... ........................ 119
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`7 .6.3 Increasing the decoupling-capacitance of power lines ........................ ............ 120
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`7 .6.4 Routing driver outputs to the pixel array .................. ....... ................................ 120
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`7.6.5 Pixel tabs to contact MET3 pixels ............................ ......... ...... ........................ 120
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`7.7 Circuit design for four-level modulation ...... ................................. .... ............... .... ..... 121
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`7.7.1 Quaternary driver schematics and functionality .... ..... ............. ........................ 121
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`7.7.2 Standard geometry MOSFET design ....................................... ... ............. ........ 123
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`CONTENTS
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`x
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`7 .7.3 Converting drive voltages by digital selection of power rails ...... .. .. ...... ...... .. . 123
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`7.7.4 Current limiting by sizing select transistors ............................ .. .. .... ............ .. ... 123
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`7.8 Layout of the quaternary backplane .... .. .. .. ..................... ......... ......... .... .... .. ............... 124
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`7 .8.1 Layout of the quaternary drivers ...................... .. ........ ............................... .. .. ... 124
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`7 .8.2 Layout of the quaternary pixel array ........................ .. ............... .. ....... .. ........ .... 124
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`7.9 Buffering of control signals ............ .. ... ....... .... ...... .... ... .. ... .. .. .. ........ .. .. ....................... 126
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`7.10 Bonding pads ..... .... .... .. ........ ... ...... ... .. .... ..... ... ............... ..... ...... ........... ... .. ................ 126
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`7 .11 Functionality tests .... ... .. .. ... .. ..... .... ... ..... .... .. ... ..... .. ..... ....... ...... .... .... ... ...................... 127
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`7 .11.1 Test of the dynamic shift register data latching and shifting .. .. .. ........ ....... .... 127
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`7.11.2 Test of frame update, level shifting and DIA conversion .......... ...... .. .. .. .. ...... 127
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`7.12 Conclusions ...................................... .... ... ....... ... .................. .. ...... .... .. ....... ............... 129
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`CHAPTERS
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`Characterisation of fabricated Roses devices
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`130
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`8.1 Introduction ....................................... .. ........ .. ... ..... ..... ... ... ............... .. .... ...... .. ...... .. .... 130
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`8.2 Initial tests of an unprocessed wafer .. ............ .. ............ .... ....... ....... .. ........ .. ....... .. .. .. .. 130
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`8.2.1 Binary array .. .. .. ......................... .. ... .... ........ .. ... ..... .. .... .... .. .... .......... .. ................ 131
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`8.2.2 Quaternary array .............. .. .......... ........ .. .......... .... .. .. ... .. ........ .... .... .. .. ...... .. .. ..... 133
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`8.3 Processing silicon backplane devices and SLM assembly ................................ ........ 135
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`8.3 .1 Optical quality mirror deposition ......... .. ..... .. ..................................... ....... .. .... . 135
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`8.3 .2 Al-etch of protective mirror coating .... .. ...................... .. .... .. .. ... .... .............. .. ... 135
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`8.3.3 Assembly of silicon backplane SLMs .... ... .... .. ................... .. .... .. .... .. .... ... ..... .... 135
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`8.4 Tests of assembled SLMs ..... .... ..... .................. ............ ........ .... ................ ...... ...... ...... 136
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`8.4.1 Initial optical inspection using the probe-station ...... ... .... ..... .... .. ..... .. .. .......... .. 136
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`8.4.2 SLM interface and carrier design ... .. ........ .. .. .... ..... ..... .. .. .. ...... .. ... ..... .. .............. 139
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`8.4.3 Imaging optical modulating using a polarising microscope ...... .. .. .... .... ... ... .... 140
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`8 .5 Holographic SLM demonstrator ...... .. ...... .... .... .. ... .. ... .............. .. ... .. ........ .. .... .. ........... 143
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`8.5.1 Replay field mapping using intensity modulation ... ... ... .. ..... .. .. ..... .................. 143
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`8.5 .2 Reflective binary-phase holographic operation .... .... .. .... .. .. .. .. .. .. .. ................... 151
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`8.6 Drive schemes issues for holographic applications ........................ .... .... .. .... .. .......... . 156
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