A compact and universal digital lock-in amplifier design for broad optical spectrum capturing

This paper reports a compact, universal and all-digital lock-in amplifier design to complete the broadband optical spectrum signal measuring, which can be utilized in the optical spectrum analysis, coded Brillouin optical time-domain sensors, and ultra-low optical signal capturing. With the development of the integrated circuit these days, all the components, including the phase detector, reference signal generator, and complex calculators, required in such system are built digitally, leading to a compact and universal design that can be implemented in the various situations. Furthermore, benefited from the 24-bit analog-digit converter (ADC) employed in the design, this lock-in amplifier has achieved a real-time dynamic range over 100dB.