Diamond Brillouin Lasers

Abstract

The coherent interaction between optical and acoustic waves via stimulated Brillouin scattering (SBS) is a fundamental tool for manipulating light at GHz frequencies. Its narrowband and noise-suppressing characteristics have recently enabled microwave-photonic functionality in integrated devices based on chalcogenide glasses, silica and silicon [1][2][3][4][5]. Diamond possesses much higher acoustic and bandgap frequencies and superior thermal properties, promising increased frequency, bandwidth and power; however, fabrication of low-loss optical and acoustic guidance structures [6] with the resonances matched to the Brillouin shift [1] is currently challenging. Here we use intense cavity-enhanced Raman generation to drive a diamond Brillouin laser without acoustic guidance. Our versatile configuration-the first demonstration of a freespace Brillouin laser-provides tens-of-watts of continuous Brillouin laser output on a 71 GHz Stokes shift with user switching between single Stokes and Brillouin frequency comb output. These results open the door to high-power, high-coherence lasers and Brillouin frequency combs, and are a major step towards on-chip diamond SBS devices.SBS interactions provide an important bridge between optical and microwave frequencies, enabling generation and signal processing capabilities with high resolution, broad bandwidth and wide tunability that far surpass capabilities of electronic components [2, 4, 7, 8]. The combination of a GHz frequency response and ultra-narrow linewidth (10s of MHz), both of which are widely tunable via the pump spectral properties [9], enables microwave processing functionality such as reconfigurable narrow-band filters, phase-shifters and time delays [7, 8,10,11]. SBS lasers also provide noise suppression via the acoustic field [12,13], and can be cascaded for ultra-low-noise lasers and frequency combs [1, 2, 14-17] in microwave synthesis [2] and spectroscopy [15]. The prospect of integrating these optical synthesis and processing capabilities onto a miniaturized format has stimulated a large effort in on-chip waveguide and resonator-based devices, predominantly in chalcogenide, silica and silicon [2, 5, 7, 9,18]. However, nonlinear absorption, thermal effects and a limited range of Brillouin frequencies (typically 5-20 GHz) in these materials [6,19,20] limit optical power handling and spectral control-both of which are key to device performance [2]-which has motivated a search for alternative and hybrid material platforms [3,[20][21][22]].Diamond's suite of exceptional optical and physical properties make it an outstanding candidate for extreme photonics applications in high-power lasers, quantum optics, bio-photonics and sensing [23][24][25]. Its high sound velocity and wide bandgap also increase the available Brillouin frequency range to , up to an order of magnitude higher than other SBS materials [19,22]. Continuous powers and power densities at hundreds of watts and 1 GW.cm −2 are routinely sustained without deleterious nonlinear effects [23,27,28] in cont...

Stable high-efficiency continuous-wave diamond Raman laser at 1178 nm

“…The emergence of SBS adversely affects the output stability and further power scaling due to the strong nonlinear coupling from the SRS field. Based on the SRS and SBS double-resonating conditions proposed in [40,41], a solution to suppress the SBS was proposed by altering the cavity length by translating mirror M1. Using steps of 0.01 mm over a range of 12.7 mm was found not to suppress the SBS.…”

“…Presently, the main challenge for power scaling is the SBS. The fact that SBS could not be suppressed with cavity length [41] indicates that mechanism for SBS generation is not well understood. The large Brillouin frequency shift of diamond crystal makes intracavity spectral filtering using volume Bragg gratings or Fabry-Pérot etalons for example, a possible method to suppress the SBS.…”

A comprehensive review on the development and applications of narrow‐linewidth lasers

“…In addition, the Brillouin laser and Brillouin frequency comb based on the Raman conversion were demonstrated in the same group. 93,94 Owing to the excellent optical and thermophysical properties of diamond, diamond Brillouin lasers exhibit high power and wavelength scalability. [95][96][97]…”

Comprehensive Thermal Analysis of Diamond in a High-Power Raman Cavity Based on FVM-FEM Coupled Method

“…In the last decade, diamond has been of interest to the laser community due to its excellent thermophysical, spectral, and nonlinear optic properties. By using a single crystal diamond with a volume of less than 0.04 cm 3 , over a kilowatt of quasi-continuous Raman laser power (in thermal quasi-steady-state) [18,19] and high power (11 W for continuouswave, and on-time power 40 W for quasi-continuous-wave) Brillouin lasing [20,21] have been demonstrated. In addition, lasers based on diamond as the gain medium provide a promising approach to high brightness beam generation [22,23] with a wide spectral range [24][25][26].…”