Small-tilt measurement based on weak-value-amplification with balanced homodyne detection

We experimentally realize a great precision enhancement in the small-tilt measurement by using a Sagnac interferometer and balanced homodyne detection (BHD) of high-order optical modes, together with the weak-value amplification (WVA) technique. Smaller minimum measurable tilt and higher signal-to-noise ratio can be obtained by using BHD, compared with the split detection. The precision of 3.8 nrad can be obtained under our present experimental condition. It is shown that combining WVA technique and BHD can strengthen each other's advantages and can behave better for some special application scenarios, such as extremely weak output, wider measurement bandwidth, etc. Moreover, the precision can be further enhanced by experimental parameter optimization.

Automated summary

We achieve a significant improvement in the precision of small-tilt measurement by combining a Sagnac interferometer, balanced homodyne detection, and weak-value amplification technique. Compared with split detection, balanced homodyne detection offers smaller minimum measurable tilt and higher signal-to-noise ratio. With our experimental setup, a precision of 3.8 nrad is obtained. The results demonstrate that the combination of weak-value amplification technique and balanced homodyne detection can complement each other's advantages and perform better in certain application scenarios, such as extremely weak output and wider measurement bandwidth. Furthermore, precision can be further enhanced through experimental parameter optimization.