摘要： High peak power, single-frequency pulsed fiber MOPA sources with extremely narrow line and nanosecond pulses are in highly demand to date. Such sources are required for various applications, including coherent LIDARs systems, remote sensing, and frequency conversion [1]. Stimulated Brillouin scattering (SBS) arising is a main obstacle to further peak power and pulse energy scaling [2]. There are several strategies for SBS suppression in the fiber MOPA have been described in the literature to date. These include exploiting a longitudinal temperature or mechanical stresses gradient in a gain fiber [3] or by using a birefringent fiber with both eigenstates excited. In [4] Stolen has demonstrated doubling of SBS threshold in birefringent fiber with equally excited fast and slow waves. Tapering of a fiber is significantly increases a SBS threshold [5].Usually, authors have used only one of abovementioned strategies for SBS mitigation. Meanwhile, all these measures might be imposed simultaneously by using a short, active, tapered, end pumped (aiming strong temperature gradient) fiber with large mode field diameter fiber. The experimental set up is shown in Fig.1. In conclusion, we have presented short (1.2m), tapered, birefringent, ytterbium doped, end pumped double clad fiber MOPA system with 40μm mode field diameter for amplification of single-frequency long pulses (100ns) for coherent LIDAR application. We have reached record 0.522mJ pulse energy and demonstrated highest to date 5kW peak power by using anisotropic active tapered double clad fiber as a gain media and exciting both slow and fast polarization waves.