We demonstrate a large energy output and a wider output spectral bandwidth from Nd:glass-based regenerative amplifiers. The maximum energy extracted from the regenerative amplifier is 24 mJ with an overall gain of 3.4 x 10⁸. The maximum output bandwidth achieved is 4.2 nm FWHM when the input pulse spectral bandwidth is 7 nm FWHM. This was made possible by a new cavity optimization technique.