We employed an atomic vapor cell, a practical component, to develop the source of biphoton quantum light. For the first time, we utilized the all-copropagation scheme and developed a high isolation technique. The source＇s linewidth and spectral brightness are the world records to date. It has a stable frequency with a wide adjustable range, a highly tunable linewidth compatible with various quantum devices, and ultrahigh brightness, leading to a key apparatus in the future quantum communication.