405nm Sat Spec

Introduction

Locking the 405nm master laser will of course require an atomic reference. (see here for level structure)

Setup

This transition has a weaker cross section, as described here. In order to observe this line, we need to heat the typical vapour cell to a higher temperature:

Data

Scanning the master laser piezo, we saw the characteristic saturated absorption peaks:

This had about the right width, given an 11MHz unresolved spread of 1-MHz-wide levels in the excited state.

So far these are averaged images — a single scan had worse signal-to-noise — so further improved optical density will be required.