High-quality single crystal diamond diffraction gratings fabricated by crystallographic etching.

Marcell Kiss,Teodoro Graziosi,Olivier J F Martin,Toralf Scharf,Adrien Toros,Niels Quack,Christian Santschi

doi:10.1364/oe.27.030371

Abstract

We demonstrate a novel method for fabricating single crystal diamond diffraction gratings based on crystallographic etching that yields high-quality diffraction gratings from commercially available <100> diamond plates. Both V-groove and rectangular gratings were fabricated and characterised using scanning electron microscopy and atomic force microscopy, revealing angles of 57° and 87° depending on the crystal orientation, with mean roughness below Ra = 5 nm on the sidewalls. The gratings were also optically characterised, showing good agreement with simulated results. The fabrication method demonstrated in this contribution shows the way for manufacturing high-quality diamond diffractive components that surpass existing devices both in quality and manufacturability.

Highlights

Diffraction gratings fabricated in single crystal diamond represent an inspiring endeavour, thanks to their exceptional material properties
We demonstrate single crystal diamond diffraction gratings fabricated by photolithography, hardmask patterning and crystallographic etching
The diamond diffraction gratings were fabricated from commercially available general grade single crystal diamond substrates (Element Six, LakeDiamond)

Summary

Introduction

Diffraction gratings fabricated in single crystal diamond represent an inspiring endeavour, thanks to their exceptional material properties. Diamond exhibits a high refractive index (2.4 at 635 nm [1]) and low absorption over a wide spectral range spanning from ultraviolet to far infrared It provides high thermal conductivity and a remarkably high laser induced damaged threshold (LIDT) [2]. Diffraction gratings are found in numerous optical systems, including monochromators [3], spectrometers [4,5,6], beamsplitters [7], continuous wave [8] and pulsed lasers [9] These are commonly fabricated by mechanical ruling [10], where the grooves are created by mechanical material removal, or by microfabrication technologies based on photolithography and subsequent etching procedures [11]. While microfabrication is typically more complex, gratings fabricated this way are well suited as moulds for creating replicas [12]

Methods

Results

Conclusion