# A versatile, high-power 460nm laser system for Rydberg excitation of ultracold potassium

## TL;DR

This paper introduces a high-power, tunable 460nm laser system with narrow linewidth suitable for Rydberg excitation in ultracold potassium, demonstrating its stability and application in two-photon spectroscopy.

## Contribution

The paper presents a versatile, high-power laser system with a broad tunable range and low noise, optimized for atomic physics experiments involving Rydberg states of potassium.

## Key findings

- Achieved over 1.5W of narrowband light tunable from 455-463 nm.
- Demonstrated two-photon spectroscopy and observed electromagnetically induced transparency.
- Verified long-term stability and capability to excite multiple Rydberg states.

## Abstract

We present a versatile laser system which provides more than 1.5W of narrowband light, tunable in the range from 455-463 nm. It consists of a commercial Titanium-Sapphire laser which is frequency doubled using resonant cavity second harmonic generation and stabilized to an external reference cavity. We demonstrate a wide wavelength tuning range combined with a narrow linewidth and low intensity noise. This laser system is ideally suited for atomic physics experiments such as two-photon excitation of Rydberg states of potassium atoms with principal quantum numbers n > 18. To demonstrate this we perform two-photon spectroscopy on ultracold potassium gases in which we observe an electromagnetically induced transparency resonance corresponding to the 35s1/2 state and verify the long-term stability of the laser system. Additionally, by performing spectroscopy in a magneto-optical trap we observe strong loss features corresponding to the excitation of s, p, d and higher-l states accessible due to a small electric Field.