Techniques to eliminate error induced due to acousto-optic modulator vibration in heterodyne interferometry

Abstract

Noise reduction and improved resolution are some serious challenges for precision measurement in the era of nanotechnology. Although several factors that lead to the loss of accuracy in precision measurement system were realized and some were eventually eliminated, some critical factors that were overlooked remain. One such factor, which has become an inherent part of the system, is that caused by the vibration of the acousto optic modulator (AOM) in heterodyne interferometry. We highlight the effect of error induced by the vibration of the AOM and, different methods of eliminating this error by the modification of the optical layout discussed. © 1999 Society of Photo-Optical Instrumentation Engineers. [S0091-3286(99)01612-8]

Drift Error Compensation Algorithm for Heterodyne Optical Seawater Refractive Index Monitoring of Unstable Signals

“…The range of the generated signal frequency indicates the stability of the generator. The signal generator used in the experimental device is Gooch & Housego's AODR 97-03307-74 (1040AF-AIF0-0.5) [18], with a center frequency of 40 MHz ± 0.1%, and according to the parameters of the frequency error range of the signal generator, the actual frequency difference ∆ f practical satisfies −0.1% × 40 MHz = −40000 Hz < ∆ f practical < 40000 Hz = +0.1% × 40 MHz (13) Fifty signal acquisition tests in calm environments were executed at different times and locations, and the frequency difference from each test was obtained according to Equation (7), as shown in Appendix A. The average value of all of the frequency differences was −1.896 × 10 −8 Hz, which is negligible.…”

“…Independent studies of drift error, by B. K. A. Ngoi (1999) [7], L. Qian (2011) [8], and B. Lin (2022) [9], have shown that the instability of the optical shift of the AOFS is a primary cause of signal drift.…”

Supplementary document for InP High Power Monolithically Integrated Widely Tunable Laser and SOA Array for Hybrid Integration - 5033234.pdf

“…However, this technique measures a lineshape function that convolves technical noise terms with the intrinsic Lorentzian line shape, also called the Schawlow-Townes linewidth, fundamental linewidth, or high frequency equivalent linewidth in literature [5][6][7][8][9]. Technical noise originates from outside the laser cavity and includes factors such as electrical driving noise and environmental noise coupling into the delayed selfheterodyne instrument [10]. These factors can be reduced with sufficient engineering and stabilization techniques for improved long term laser stability and instrument performance at the expense of setup complexity [11,12].…”

Implementation of a loss-compensated recirculating delayed self-heterodyne interferometer for ultranarrow laser linewidth measurement

“…The frequency fluctuation due to the environmental vibration can therefore be partially canceled. 7 Another important component is the coupler. The coupling coefficient directly affects the maximum order of the beat notes we can obtain.…”