## 1 Introduction  
Remarkable progress in recent years with the chirped-pulse amplification (CPA) technique [1] provides great opportunities for experimental study of the behavior of matter in ultrahigh electromagnetic fields in small-scale laboratories [2, 3]. Recently, much effort in CPA laser development has been expended towards achieving high intensities such as the 100 TW or even petawatt (PW) power level [4, 5, 6, 7, 8, 9, 10, 11, 12, 13]. Consequently, high intensity laser-matter interaction studies can now be done with focused peak intensities up to 10\({}^{20}\) W/cm\({}^{2}\) or even to 10\({}^{22}\) W/cm\({}^{2}\)[7, 11, 12]. Currently, the development of high power femtosecond laser system having a 200 PW level is being pursued through European Extreme Light Infrastructure (ELI) project [13]. This progress in high-field science gives rise to the birth of new applications and breakthroughs which include relativistic particle acceleration [14, 15, 16, 17, 18, 19, 20], bright X-ray source generation [21, 22, 23, 24, 25, 26, 27], and nuclear activation [28, 29]. In order to reach these intensities, great efforts have been directed to increasing the pulse energy and reducing the pulse duration. For many experiments increased peak intensities require a commensurate improvement in temporal contrast. Here, the temporal contrast (referred to henceforth as simply contrast) is taken to be the ratio of the peak intensity of the main pulse to the intensity of the amplified spontaneous emission (ASE) background and has values much greater than one. The temporal contrast is a critical characteristic of femtosecond high intensity laser pulses for many experiments where it is important to avoid any modification of the target, such as pre-plasma formation, before arrival of the main femtosecond laser pulse [30, 31]. For example, at peak intensities of 10\({}^{21}\) to 10\({}^{22}\) W/cm\({}^{2}\) and contrast in the range 10\({}^{6}\)-10\({}^{8}\) the prepulse intensity level (and duration) is above threshold for pre-plasma formation on a solid target. In this low contrast case the ASE alters the physical condition of the target for the main intense pulse. In order to avoid the preplasma formation before the main femtosecond pulse of such high intensity arrives, it is essential to increase the contrast level to 10\({}^{12}\) or more. The use of high contrast pulses for interaction of high intensity lasers with solid targets is of primary importance for a number of experiments. Specifically, in the last several years, multi-MeV ion acceleration from laser-irradiated thin target foils is an area that has received considerable interest and has been widely examined both experimentally and theoretically. When an ultra-intense laser pulse is incident on a thin target foil, protons, arising from hydrogenated contamination layers on the surface of the foil, are accelerated owing to electric-field formation. Experimental data and particle in cell (PIC) simulations of laser-acceleration of ions suggest the maximum proton energy increases significantly as the target thickness is reduced for sufficiently high laser intensity and contrast [14, 15, 31]. Because contrast is crucial for accessing high field physics in desired targets it has become a major issue, and is today under serious investigation throughout the world. Various pulse cleaning techniques have been investigated to suppress the ASE for improving the contrast. These include using cross-polarized wave (XPW) generation [32, 33], the saturable absorber [34, 35], the plasma mirror [36, 37], self-diffraction in bulk Kerr media [38], and optical parametric amplification (OPA) [9]. XPW generation can provide good contrast of greater than 10\({}^{10}\) at the multiterawatt power level. Although the XPW technique can accommodate input intensities up to TW/cm\({}^{2}\), the efficiency of this technique is limited to the range of 10%-20% [39].