2.1. Higher efficiency

This is expected since all the wavelength conversion processes for generation of the harmonics up to the near UV are from second order nonlinearity, instead of third order nonlinearity in the Raman sideband approach.

Figure 2. (a) Schematic of the Raman sideband generation approach (b): Schematic of the cascaded harmonics approach

Frequency-Synthesized Approach to High-Power Attosecond Pulse Generation and Applications: Generation…

http://dx.doi.org/10.5772/intechopen.78269

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Figure 3. (a) Synthesis of a square wave with modes at frequency from the fundamental to the 10th harmonic of the laser output. (b) Same as (a) except that the amplitude of the mode at the fundamental frequency is attenuated by 10%.

A Q-switched Nd:YAG laser and its harmonics up to the fifth order is used as the laser source.

## 2.2. Simplicity and compactness

Only one pump laser is required in the present scheme (see Figure 2(b)) rather than two in the Raman sideband approach.
