Diamond sodium guide star laser

Abstract

Laser guide stars based on the mesospheric sodium layer are becoming increasingly important for applications that require correction of atmospheric scintillation effects. Despite several laser approaches being investigated to date, there remains great interest in developing lasers with the necessary power and spectral characteristics needed for brighter single or multiple guide stars. Here we propose and demonstrate a novel, to the best of our knowledge, approach based on a diamond Raman laser with intracavity Type I second-harmonic generation pumped using a 1018.4 nm fiber laser. A first demonstration with output power of 22 W at 589 nm was obtained at 18.6% efficiency from the laser diode. The laser operates in a single longitudinal mode (SLM) with a measured linewidth of less than 8.5 MHz. The SLM operation is a result of the strong mode competition arising from the combination of a spatial-hole-burning-free gain mechanism in the diamond and the role of sum frequency mixing in the harmonic crystal. Continuous tuning through the Na D line resonance is achieved by cavity length control, and broader tuning is obtained via the tuning of the pump wavelength. We show that the concept is well suited to achieve much higher power and for temporal formats of interest for advanced concepts such as time-gating and Larmor frequency enhancement.

Numerical Simulation of Long-Wave Infrared Generation Using an External Cavity Diamond Raman Laser

“…In addition, due to the excellent thermophysical properties of diamond, stable LWIR Raman operation without heat accumulation can be realized when the pump pulse width is in the order of 100 microseconds, meanwhile, the repetition rate can be up to kHz-level [10,25], even if its quantum defect is significantly higher than that of the short wave. As there is no spatial hole burning effect in the process of Raman conversion [26][27][28][29], the theoretical study also provides a preliminary reference for realizing the operation of narrow linewidth LWIR lasing. Besides, the excellent Brillouin characteristics of diamond also make it possible to realize low-noize LWIR Brillouin lasing and Brillouin frequency combs in the future [30,31].…”

Development of Single-Longitudinal-Mode Selection Technology for Solid-State Lasers

“…e Raman cavity is based on a simple standing-wave structure pumped by a multilongitudinal mode laser. Subsequently, the same group [5] demonstrated a SLM 589 nm laser with near-diffraction limited beam quality generated in a standing-wave diamond Raman resonator with intracavity second-harmonic generation. With a 63 W 1018 nm pump, 589 nm laser with output power up to 22 W was achieved.…”

“…With only one fundamental frequency component, singlelongitudinal-mode (SLM) lasers have the advantages of narrow linewidths and low phase noise and are therefore ideal for applications where a high-coherence light source is required, including Doppler wind lidar, atmospheric composition measurement, coherent optical communication, gravitational wave detection, sodium guide star, and nonlinear optics [1][2][3][4][5]. In general, if the linewidth of an SLM laser is narrower than the resolution of a spectrum analyzer or the nonlinear gain bandwidth of a specific medium, it is assumed to be a single-frequency laser.…”

Diamond Raman laser: a promising high-beam-quality and low-thermal-effect laser

“…The results show that the self-suppression provided by additional gain competition strongly reduces the instability of SLM caused by thermally induced cavity length. In 2020, the author first realized a 22 W of CW output at 589 nm with neardiffraction-limited beam quality in the diamond Raman and second-harmonic generation resonator [74] . The 1018 nm ytterbium-doped fiber (YDF) laser as the pump laser consists of two parts: fiber Bragg grating oscillator and one-stage YDF amplifier.…”