Emission Spectrum of a Diode Laser with Microwave Modulation of the Injection Current

Emission spectrum of a diode laser with microwave modulation of the injection current was studied. Dependences of amplitudes of low-frequency and high-frequency sidebands and carrier due to microwave modulation frequency were investigated. The dependences of the spectrum on the modulation frequency were obtained in a wide frequency range of the microwave generator, from 2.8 to 3.8 GHz. This dependences for 4 different values of the diode laser injection current were obtained: 52 mA (near the threshold), 57 mA, 62 mA and 67 mA. For different values of the injection current, a clear weakening of the oscillating nature of the amplitudes was observed, and at a current of 67 mA, a wide smooth contour was obtained covering the modulation frequency range of ~ 0.5 GHz, which significantly reduces the criteria for stabilizing the cavity length. The absolute magnitude of the amplitudes and, correspondingly, the modulation efficiency increased, that can be used for effective pumping of CPT resonances in a cell with rubidium.