# Two-color photoionization of calcium using SHG and LED light

## TL;DR

This paper introduces a simplified method for loading calcium ions into a trap using resonant laser excitation and LED ionization, reducing complexity and maintenance compared to previous techniques.

## Contribution

The authors demonstrate a novel, low-maintenance photoionization approach combining coherent laser excitation with LED ionization for calcium ions.

## Key findings

- Efficient loading of calcium ions using the described method.
- Reduced setup complexity and maintenance requirements.
- Comparable ionization efficiency to traditional methods.

## Abstract

We present a photoionization method to load single 40Ca ions in a linear Paul trap from an atomic beam. Neutral Ca I atoms are resonantly excited from the ground state to the intermediate 4s4p 1P_1-level using coherent 423nm radiation produced by single-pass second harmonic generation in a periodically poled KTiOPO_4 crystal pumped with an 120mW extended cavity diode laser. Ionization is then attained with a high-power light emitting diode imaged to the trap center, using an appropriately designed optical system composed of standard achromatic doublet lenses. The setup simplifies previous implementations at similar efficiency, and it hardly requires any maintenance at all.