Increasing the SBS threshold by applying a flexible temperature modulation technique with temperature measurement of the fiber core

Abstract

In this paper, we proposed a temperature modulation technique for the suppression of stimulated Brillouin scattering (SBS). This technique can achieve different kinds of temperature distributions in a high-power laser system with compact design and safe operation. We built up an experiment platform and a theoretical model to evaluate the performance of the temperature modulation technique by applying different temperature distributions along the gain fiber. A total of 3.3 dB SBS suppression can be achieved with only a 70 °C temperature gradient at 36 W output power in this experiment. During the experiment, optical frequency domain reflectometry (OFDR) was used to measure the temperature distributions of the gain fiber core under the effect of the temperature modulation technique. By further simulating and optimizing the temperature distributions, we can see the potential of SBS suppression rise to 3.5 dB with this temperature modulation technique. Through these studies, we demonstrated our temperature modulation technique with high flexibility and great potential for SBS suppression in a high-power single-frequency laser system.

Realization of in Situ Fiber-Core Temperature Measurement in a Kilowatt-Level Fiber Laser Oscillator: Design and Optimization of the Method Based on OFDR

“…To verify the feasibility of the measurement experiment, we used the theoretical model introduced previously [21,22] to simulate the fiber temperature of the kilowatt oscillator. In this model, rate equations for fiber lasers [36][37][38][39] and heat conduction equations for radial thermal distribution [12,14] were combined.…”

“…Recently, our group has mastered and achieved a fiber-core temperature measurement technique in the high power regime. This technique has been applied in the study of nonlinear effect suppression by temperature modulation [21]. The fiber-core temperature in hundred-watt-level single-mode fiber laser oscillators has also been previously obtained [22].…”

High‐Power Laser Systems

“…[275,276] A 3.3 dB SBS suppression ratio has been reported by temperature gradient control at 70 °C. [277]…”

Investigation of the confined-doped fiber on single-mode operating and power scaling in all-fiber single-frequency amplifiers

“…Till now, a variety of approaches have been reported to provide effective suppression on these two effects, separately. For example, approaches like enlarging the mode area or shortening fiber length [7][8][9], employing acoustically tailoring technique [10], introducing strain or temperature gradient [11][12][13], using gain competition strategy [14][15][16] and counter-pumping scheme [17,18] are always applied to suppress the SBS effect. Meanwhile, plenty of effective methods are utilized in the high-power laser systems to mitigate the TMI effect, such as coiling active fiber [19,20], optimizing pumping wavelength or signal wavelength [21][22][23], suppressing the noise property [24,25], reducing the fiber core to pump cladding ratio [26,27], and using gain-tailoring technique [28,29].…”