Electro-Optics Handbook, Second Edition
Developed by a towering figure in the field, this valuable, all-inclusive guide thoroughly explains and discusses the use of optical devices and light in electronics systems.
TABLE OF CONTENTS Electro-Optics Handbook, Second Edition
Chapter 9: ULTRASHORT OPTICAL PULSES: SOURCES AND TECHNIQUES
Li Yan, P.-T. Ho, and Chi. H. Lee
9.1 PRINCIPLES OF ULTRASHORT PULSE GENERATION
Since the invention of the laser four decades ago, generating ever shorter laser pulses has always been one of the most important and active areas of laser physics and engineering. Numerous methods have been developed to generate ultrashort laser pulses. Rapid advances have been made, especially in the last decade during which optical pulses from various lasers have been pushed down to the femtosecond region, and the pulse peak power has reached the multi-terawatt level. In general, there are three basic methods: mode locking, gain switching, and pulse shaping and compression. In this section, we briefly describe the basic principles of these methods; more detailed discussions are given in Sec. 9.2.
Mode Locking
Mode locking is the first and arguably the most important method of generating ultrashort pulses, and much numerous theoretical and experimental work has been done on this subject since the earliest demonstrations.1 -4
Mode Locking in Inhomogeneously Broadened Lasers. For an ideal inhomogeneously broadened laser, different species of atoms contribute to different axial modes. Thus, each individual mode saturates independently, and many modes can lase simultaneously. The electric field of the light in the resonator can be written as
| (9.1) |  |
where A k and ? k are the amplitude and the phase of the mode designated by k. For any smooth mode amplitude distribution, the relative phases of modes dominate the temporal structure of light. In the...
Copyright The McGraw-Hill Companies, Inc. 2000 under license agreement with Books24x7
