Synchronized subharmonic modulation in stimulated emission microscopy

Subir Das, Yi Chih Liang, Shunji Tanaka, Yasuyuki Ozeki, Fu Jen Kao

Research output: Contribution to journalArticlepeer-review

5 Scopus citations


In this work, we have demonstrated a stimulated emission (SE)-based pump-probe microscopy with subharmonic fast gate synchronization, which allows over an order of magnitude improvement in signal-to-noise ratio. Critically, the alternative way of modulation is implemented with the highest possible frequency that follows the lasers’ repetition rate. Its working is based on a homemade frequency divider that divides the repetition frequency (76 MHz) of the Ti:sapphire (probe) laser to half of the repetition frequency, 38 MHz, which is used to synchronously drive the pump laser and to provide the reference signal for the ensuing lock-in detection. In this way, SE can be detected with sensitivity reaching the theoretical (shot noise) limits, with a much lower time constant (0.1 ms) for faster image acquisition.

Original languageEnglish
Pages (from-to)27159-27167
Number of pages9
JournalOptics Express
Issue number19
StatePublished - 16 Sep 2019


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