Many applications such as high power laser locking and seeding, atom cooling and trapping or optical heterodyning and coherent communication, require a single-frequency emission with high frequency stability and low noise. Narrow linewidth single-frequency emission at 1.064µm is well known and usually monolithic ring cavities (such as Non Planar Ring Oscillators) is a good solution. In this paper, we demonstrate a stable single-frequency emission at 1.064μm with noise reduction at a power of 500mW based on a linear monolithic cavity with Nd:YAG amplifier. In the past, we have already demonstrated the efficiency and the reliability of monolithic cavities used in our standard product line (LaserBoxx LCX-532S, LCX-553S and LCX-561S). In this presentation, single-frequency operation is achieved by a double Lyot filter, the first filter selecting the emission band of Nd:YAG and the second filter selecting the longitudinal mode and achieves the single-frequency operation. We report narrow linewidth <100kHz. By introducing a nonlinear crystal (KTP for second harmonic generation (SHG) at 532nm), we modify the laser dynamics and reduce the oscillation relaxation and consequently the laser noise (<0.2% RMS). We also report a good laser frequency stability due to our monolithic cavity (<100 MHz for short-term behavior and <1pm for long-term behavior), a frequency tuning capabilities (up to 10pm without mode hopping and up to 1nm with mode hopping), a power stability less than 2% for a laser base temperature from 15°C to 45°C at 500mW, a good optical efficiency (<25%) and a high beam quality (M2<1.2).