Laser-based device utilizing multiple laser beams

An apparatus comprising:

• a first laser transmitter having a first self-mix carrier frequency;
• a second laser transmitter having a second, different, self-mix carrier frequency;
• a first monitor photodiode to receive a first optical signal from the first laser transmitter, and to output a first electric signal;
• a second monitor photodiode to receive a first optical signal from the second laser transmitter, and to output a second electric signal;
• an electric connection to connect together the first electric signal and the second electric signal, forming a combined electric signal;
• a single laser receiver to receive the combined electric signal and to generate from it a spectrum that corresponds to both (i) optical feedback of the first laser transmitter, and (ii) optical feedback of the second laser transmitter;
• a laser usefulness estimator (i) to estimate self-mix usefulness of optical feedback received by the first laser transmitter, and (ii) to estimate self-mix usefulness of optical feedback received by the second laser transmitter;
• a selective activation module (a) to selectively reduce a level of power provided to the first laser transmitter, while maintaining the first laser transmitter activated, and (b) to maintain a level of power provided to the second laser transmitter, if an estimated self-mix usefulness value of the first laser transmitter is smaller by at least a pre-defined ratio from an estimated self-mix usefulness value of the second laser transmitter.