# Three ways to select from two attosecond pulses

## TL;DR

This paper explores methods to generate and select between single attosecond pulses using spectral filtering and propagation effects, enabling control over pulse energy domains for advanced ultrafast spectroscopy.

## Contribution

It introduces a novel approach to produce and select different single attosecond pulses by spectral filtering during propagation in a macroscopic medium.

## Key findings

- Filtering high harmonics yields two distinct SAPs in different spectral domains.
- Feasible experimental setup proposed for energy domain-specific SAP generation.
- Double pulse emission with fixed temporal separation observed without filtering.

## Abstract

We demonstrate that by filtering high harmonics it is possible to obtain two different single attosecond pulses (SAP) resulting from naturally separated spectral domains formed during propagation in the macroscopic medium. We propose a feasible experimental configuration in which one can obtain a SAP in a lower energy domain (<300 eV), or another SAP in a higher energy domain (>300 eV). Without filtering, a double attosecond pulse emission with fixed temporal separation is obtained. The gap between the two spectral domains is close to the onset of the water window.