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Physics 2012; 8 416-421.

2012).

**Chapter 0**

**Chapter 2**

**Femtosecond Laser Cavity Characterization**

Ultrafast pulses are used now days in physics, engineering, medicine and other research areas such as, materials processing, time resolved spectroscopy, optical coherence tomography, pulse propagation, evolution of fast chemical processes, time resolved interference, etc. It is important to understand the physical processes that govern ultra fast laser pulse generation and shaping. In the present work, we characterize and find optimum operating conditions for a commercial Ti:Sa mode locked laser oscillator that generates pulses around 60 fs duration at

The sharply peaked time structure at the oscillator output is explained in terms of the superposition of monochromatic waves with integer wavelength multiples of the round trip of the cavity. If a large number of waves with the same absolute phase are added with periodically shifted frequencies, the amplitude envelope becomes a periodically peaked train of temporal pulses. In Ti:Sa oscillators self mode-locking is achieved via Kerr lens mode-locking (KLM). The cavity is tuned so that self focusing of the more intense beam profile

The ultrafast oscillator is pumped by a Nd:YVO4 CW laser. This laser is intra-cavity frequency doubled, the power output at 532 nm is 2.07 W. The pump beam is steered via two 45° mirrors into the IR cavity. The beam is focused into the Ti:Sa crystal with a 50 mm focal length lens as shown in figure 1. This beam passes through an IR convex mirror (C1) before reaching the active medium. The Ti:Sa emission resonates in a folded cavity comprising 2 concave mirrors and 6 plane mirrors. The group velocity dispersion (GVD) is compensated with a two prisms setup. A variable slit is placed between the back resonator mirror and the second prism. Figure 1 shows the Quantronix Ti-light laser layout and table 1 lists its main components. The oscillator together with an amplifier and a parametric generator were placed on a very stable

In section 2, we revise the mathematical description of ultra short pulses. In particular, Gaussian pulses and hyperbolic secant pulses bringing together results that are scattered here

and reproduction in any medium, provided the original work is properly cited.

©2012 Fernández-Guasti et al., licensee InTech. This is an open access chapter distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original

© 2012 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution,

80 MHz repetition rate. Typical output power is 200 mW in mode locked operation.

E. Nava-Palomares, F. Acosta-Barbosa, S. Camacho-López

Additional information is available at the end of the chapter

and M. Fernández-Guasti

http://dx.doi.org/10.5772/50174

**1. Introduction**

is favored.

passively damped holographic table [1].

work is properly cited.
