Naoki, Vicky

We measured the seed and pump mode matching to OPO. The measured seed mode matching is 82% and pump mode matching is 73% at most.

First we blocked the pump and injected the seed to OPO. The seed launch power was set to 1.8 mW. We scanned the OPO PZT and measured the seed OPO transmission (Fig. 1). The mode matching of seed is calculated as 13.09/(13.09+2.06+0.42+0.30+0.09) = 82%.

Then we blocked the seed and injected the green pump to OPO. We decreased the pump power from 10 to 2.6 mW to avoid the saturation of OPO green trans PD. We will go to SQZT7 and reduce the PD gain. We scanned the OPO PZT and measured the pump OPO transmission (Fig. 2). The largest higher order mode is HG10 (yaw misalignment). The symmetric peaks around TEM00 and HG10 should be their sidebands. Ignoring those sidebands and some higher order modes below 1, the upper limit of mode matching of pump is calculated as 15.06/(15.06+5.46)=73%.