# Building blocks for future detectors: Silicon test masses and 1550 nm laser light

## TL;DR

This paper explores the potential of using silicon test masses and 1550 nm laser light to enhance the sensitivity of future gravitational wave detectors, addressing thermal and quantum noise challenges.

## Contribution

It compares properties of silica and silicon test masses and discusses recent advances in laser technology relevant for next-generation detectors.

## Key findings

- Silicon test masses at low temperatures can reduce thermal noise.
- 1550 nm laser light is promising for decreasing quantum noise.
- Silicon and 1550 nm technology are potential building blocks for future detectors.

## Abstract

Current interferometric gravitational wave detectors use the combination of quasi-monochromatic, continuous-wave laser light at 1064 nm and fused silica test masses at room temperature. Detectors of the third generation, such as the Einstein-Telescope, will involve a considerable sensitivity increase. The combination of 1550 nm laser radiation and crystalline silicon test masses at low temperatures might be important ingredients in order to achieve the sensitivity goal. Here we compare some properties of the fused silica and silicon test mass materials relevant for decreasing the thermal noise in future detectors as well as the recent technology achievements in the preparation of laser radiation at 1064 nm and 1550 nm relevant for decreasing the quantum noise. We conclude that silicon test masses and 1550 nm laser light have the potential to form the future building blocks of gravitational wave detection.