Dependence of residual amplitude noise in electro-optic phase modulators on the intensity distribution of the incident field

Juna Sathian, Esa Jaatinen

Research output: Contribution to journalArticlepeer-review

3 Citations (Scopus)

Abstract

Our results demonstrate that photorefractive residual amplitude modulation (RAM) noise in electro-optic modulators (EOMs) can be reduced by modifying the incident beam intensity distribution. Here we report an order of magnitude reduction in RAM when beams with uniform intensity (flat-top) profiles, generated with an LCOS-SLM, are used instead of the usual fundamental Gaussian mode (TEM00). RAM arises from the photorefractive amplified scatter noise off the defects and impurities within the crystal. A reduction in RAM is observed with increasing intensity uniformity (flatness), which is attributed to a reduction in space charge field on the beam axis. The level of RAM reduction that can be achieved is physically limited by clipping at EOM apertures, with the observed results agreeing well with a simple model. These results are particularly important in applications where the reduction of residual amplitude modulation to 10-6 is essential.

Original languageEnglish
Article number125713
JournalJournal of Optics (United Kingdom)
Volume15
Issue number12
Early online date24 Oct 2013
DOIs
Publication statusPublished - 1 Dec 2013
Externally publishedYes

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