▎ 摘　　要

NOVELTY - The laser device (100) has a graphene saturable absorber (130) disposed at least partially between the surfaces of highly and partially reflective mirrors (110,120). The absorber operates as a variable loss mechanism in the optical cavity allowing population inversion if the gain material exceeds the lasing threshold without the graphene and causing the stored optical energy to be released in optical pulses. The laser device emits pulses stimulated coherent radiation through the second mirror with center wavelengths of about 1,800 nanometers or more and about 25,000 nanometers or less. USE - Linear cavity laser device. ADVANTAGE - The saturable absorber can initiate mode-locking or phase-locking of the laser by providing lower loss to a multiple longitudinal optical modes with a specific phase relationship within the laser resonant cavity, if the gain bandwidth and laser cavity simultaneously support a large optical bandwidth. For passive mode-locking in a laser, an ideal saturable absorber selectively absorbs low-intensity light, while transmitting or reflecting light which is of sufficiently high intensity, thus acting as an optical gate. The linear cavity laser may include a sensing region within the optical cavity for inserting gas samples to be measured to determine the gas molecules within the sensing region, and the laser device can be operated in the frequency comb spectroscopy mode to permit enhanced sensing of the gas molecules within sensing region. The facet on the output end may be an anti-reflection coating, and the facet may be titled in certain embodiments to prevent or mitigate feedback, e.g. minimize or reduce Fabry-Perot resonances, due to the residual facet reflectivity. DESCRIPTION OF DRAWING(S) - The drawing shows the partial sectional side elevation view illustrating a linear cavity laser device. Laser device (100) Highly reflective mirror (110) Partially reflective mirror (120) Graphene saturable absorber (130) Semiconductor optical amplifier (140)