Amplified Spontaneous Emission in a Ti:sapphire Regenerative Amplifier

Amplified spontaneous emission power and contrast ratio in a linear miltipass Ti:sapphire regenerative amplifier with a wavelength centered at 1054 nm are calculated and measured. It is shown that the passive losses of a seed pulse and the losses in coupling to the regenerative amplifier cavity mode degrade the intensity contrast ratio to 10-6 -10-7 . The advantage of an optical parametric chirped pulse amplifier with respect to the contrast ratio is discussed.