22.5-W narrow-linewidth diamond Brillouin laser at 1064 nm

Abstract

Stimulated Brillouin scattering (SBS), with its advantages of low quantum defect and narrow gain bandwidth, has recently enabled an exciting path toward narrow-linewidth and low-noise lasers. Whereas almost all work to date has been in guided-wave configurations, adaptation to unguided Brillouin lasers (BLs) offers a greater capacity for power scaling, cascaded Stokes control, and greater flexibility for expanding wavelength range. Here, we report a diamond Brillouin laser (DBL) employing doubly resonant technology at 1064 nm. Brillouin output power of 22.5 W with a linewidth of 46.9 kHz is achieved. The background noise from the pump amplified spontaneous emission (ASE) is suppressed by 35 dB. The work represents a significant step toward realizing Brillouin oscillators that simultaneously have high power (tens-of-watts+) and kHz-linewidths.

Linewidth narrowing in free-space running diamond Brillouin lasers

“…The pump beam was injected into the fundamental mode of the Brillouin cavity using focusing lenses (f1 and f2) and reflectors (HR1 and HR2). In addition, the cavity length was adjusted to support the dual resonance of the pump and Stokes field frequencies [ 29 ] . Frequency locking of the pump field to the cavity was achieved using the Pound–Drever–Hall frequency stabilization technique [ 31 ] .…”

“…The resonant width γ , determined by the coupler reflectivity and inherent loss of the cavity, is of the same order of magnitude as the Brillouin gain width Γ (2π × 5.3 MHz) of the diamond at 1064 nm [ 29 ] . Therefore, the current system does not satisfy the adiabatic approximation ( γ << Γ ), that is, the Stokes linewidth behavior is dominated by the phase diffusion of the pump, which is similar to the linewidth behavior of most single-pass pumped fiber BLs [ 22 , 26 ] .…”

“…However, even with these impressive demonstrations, the characteristics of Stokes linewidth narrowing in spatially structured BLs have not been reported so far, which has been the most crucial basis for extensive research and development of BLs. In our previous study, we reported that the single-frequency BL output at 1064 nm and 46.9 kHz exhibited severe broadening compared with the linewidth of the pump (~7 kHz), which was attributed to the effect of technical noise at that time [ 29 ] .…”

High-SMSR wavelength-swept laser with a CL-band mode-hopping free tuning range

“…Several types of wavelength-swept lasers, such as external-cavity semiconductor lasers (ECSLs), dye lasers, distributed Bragg reflector lasers, tunable solid-state lasers, verticalcavity surface-emitting lasers, distributed feedback lasers, and optical non-linear frequency conversion-based lasers have been developed in the last 50 years [13][14][15][16][17][18][19][20][21]. Compared to other types of wavelength-swept laser, ECSL has the prestigious characteristics of a large tuning range, high signal-to-source spontaneous emission ratio, narrow linewidth, and low cost, which is one of the most versatile measuring tools [22][23][24].…”

178-W picosecond green laser with active beam-pointing stabilization

“…High-power laser sources with high beam quality and spectral diversity are of broad interest for various applications [1][2][3][4][5]. Among them, ultrashort pulse (picosecond and femtosecond) lasers are widely used in industrial processing, precision manufacturing, and waveguide etching because of their negligible heat-affected zones [6][7][8][9][10].…”