The authors report the observation of cw laser-excited visible luminescence at the E//1 minus E//1 plus DELTA //1 direct gaps in n-type Ge with N//e approximately 10**1**8 cm** minus **3. The phenomenon appears to be induced by participation of the high density of free electrons in the E//1 minus E//1 plus DELTA //1 transitions at the L-point (2. 1 and 2. 3 ev) since the luminescence is not observed in either pure of p-type Ge. The authors used this luminescence to investigate the effect of doping on the band structure of bulk doped and also of phosphorus implanted laser annealed Ge. Shifts and broadening of the E//1 minus E//1 plus DELTA //1 energies and also Burstein-Moss-Fermi energy shifts have been observed. The results for bulk Ge go over smoothly and overlap with the results for the laser annealed material.