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Contents

1 From Optical MEMS to Micromechanical Photonics ....... 1
1.1 Micromechanical Photonics – An Emerging Technology . . . . . . . 1
1.2 Fabrication Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.2.1 Bulk and Surface Micromachining. . . . . . . . . . . . . . . . . . . 3
1.2.2 Three-Dimensional Micromachining. . . . . . . . . . . . . . . . . . 5
1.2.3 Monolithic Integration – Micromachining for an LD. . . . 10
1.3 Miniaturized Systems with Microoptics and Micromechanics . . 11
1.3.1 Important Aspects for Miniaturization . . . . . . . . . . . . . . . 11
1.3.2 Light Processing by Micromechanics . . . . . . . . . . . . . . . . . 12
1.3.3 Kinetic Energy of Light . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
1.3.4 Micromechanical Control by Optical Pressure . . . . . . . . . 20
1.4 Integrated Systems with LDs and Micromechanics . . . . . . . . . . . 21
1.4.1 Tunable LD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
1.4.2 Resonant Sensor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
1.4.3 Optical Encoder . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
1.4.4 Integrated Flying Optical Head . . . . . . . . . . . . . . . . . . . . . 24
1.4.5 Blood Flow Sensor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
1.5 Future Outlook of Optical MEMS and Micromechanical
Photonics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

2 Extremely Short-External-Cavity Laser Diode ............. 31
2.1 Background ............................................. 31
2.2 Theoretical Analysis ..................................... 32
2.2.1 LasingCondition of a Solitary LD . . . . . . . . . . . . . . . . . . . 32
2.2.2 Effective Reflectivity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
2.2.3 Light Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
2.2.4 Wavelength . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
2.3 Experimental Analysis ................................... 41
2.3.1 Experimental Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
2.3.2 Light Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
2.3.3 Wavelength and Spectrum Characteristics . . . . . . . . . . . . 45