Frequency divide-by-two (2:1) and divide-by-three (3:1) optical parametric oscillators (OPOs) are basic devices for the implementation of future accurate optical frequency division chains. We report our latest development toward a phase-locked 3:1 frequency division of a radiation at λp ≈ 843 nm (355.9 THz), using doubly resonant oscillators (DROs) based on silver gallium sulfide (AgGaS2 or AGS) and multigrating periodically poled lithium niobate (PPLN). Although stable single-mode pair operation is achievable without any active cavity length servo with the AGS-DRO, because of a strong passive thermal feedback servo, the PPLN-DRO requires an active intensity side-of-fringe locking servo to maintain long-term, single-mode pair operation. To overcome the limited idler output power (< 1 mW) due to the weak mirror transmissivity at 2.53 μm, a CaF2 Brewster-oriented plate was inserted in a longer-cavity PPLN-DRO as a variable output coupler. About 3 mW of idler wave is thus coupled outside the cavity, yielding 15 nW of doubled-idler. We obtained a 30 dB signal-to-noise ratio beatnote in a 100 kHz resolution bandwidth of a spectrum analyser. This beat signal will be used to phase-lock the divider.
|Number of pages||7|
|Journal||IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control|
|Publication status||Published - Sep 2000|
ASJC Scopus subject areas
- Acoustics and Ultrasonics
- Electrical and Electronic Engineering