DFB laser chip technology is basically mastered by Germany, the United States, Japan and other developed countries, such as Germany's Nanoplus, Sacher, Eagleyard, Toptica, the United States' Thorlabs, EM4, Power Technology, Sarnoff, and Japan's NTT, O Clara and other companies.
There are many manufacturers, but few can realize commercial production, mainly Nanoplus, Eagleyard, NTT, Thorlabs and so on.