YAG Single-crystal Fiber Laser Research Articles

1.7 μm LD Resonantly Pumped Tm∶YAG Single Crystal Fiber Laser

1.7 μm LD Resonantly Pumped Tm∶YAG Single Crystal Fiber Laser

High-efficiency tandem Ho:YAG single-crystal fiber laser delivering more than 100 W output power

Abstract We report on a high-efficiency, high-power tandem Ho:YAG single-crystal fiber (SCF) laser in-band pumped by a Tm-doped fiber laser at 1907 nm. In addition to the uniform heat distribution resulting from the large surface-to-volume ratio of this fiber-like thin-crystal rod, the long gain region provided by the tandem layout of two SCFs enables high lasing efficiency and power handling capability. More than 100 W output power is achieved at 2.1 μm, corresponding to a slope efficiency of 70.5% and an optical-to-optical efficiency of 67.6%. To the best of our knowledge, this is the highest output power and efficiency ever reported from SCF lasers in the 2-μm spectral range.

High-efficiency Ho:YAG single-crystal fiber laser in-band pumped by a 1.9 μm laser diode

We report on a 10-watt-level, efficient 2 μm Ho:YAG (0.6 at.% Ho3+ doped Y3Al5O12) single crystal fiber (SCF) laser in-band pumped by a 1.9 μm laser diode. Benefiting from the high gain of the SCF and the unique propagation features of the pump and laser beams, a maximum output power of 10.77 W is achieved with T OC = 20%, corresponding to a slope efficiency of 61.8%. The higher efficiency of 64.8% and the output power of 9.8 W are obtained with T OC = 50%. Compared to the traditional bulk crystal, wave-guiding of the pump light in the SCF can extend the gain region and thus improve the laser efficiency, which provides a simple and effective method to improve the utilization rate of the pump light even for the low-brightness laser diodes.

63 W wing-pumped Tm:YAG single-crystal fiber laser.

We present a high-power continuous-wave (CW) Tm:YAG single-crystal fiber (SCF) laser wing-pumped by laser diodes at 791 nm. A maximum output power of 63.3 W is achieved at ∼ 2.01 µm, corresponding to a slope efficiency of 34.2%. This is, to the best of our knowledge, the highest power obtained from the SCF laser in the 2 µm spectral range. In addition to the wing pumping scheme, the large surface-to-volume ratio of such fiber-geometry crystalline rod with diffusion-bonded undoped YAG end caps are benefited for the spatial uniform distribution of pump intensity and thermal load, and thus improving the power scalability.

Compact Q-switched Nd:YAG single-crystal fiber laser with 794 nm laser diode pumping

A promising Nd:YAG single-crystal fiber (SCF) was successfully fabricated by the laser-heated pedestal growth method. The compact passively Q-switched laser has been realized for the first time with a 794 nm laser diode pumping. Pulsed laser performances of this SCF were investigated in detail with a flat-flat resonator. Under the absorbed pump power of 2.50 W, the peak power of 274.24 W was obtained with 19.41 ns pulse duration width and 65.94 kHz repetition rate.

采用解析法对Nd:YAG单晶光纤的温度场研究

采用解析法对Nd:YAG单晶光纤的温度场研究

35 W continuous-wave Ho:YAG single-crystal fiber laser

We report on a high-power Ho:YAG single-crystal fiber (SCF) laser inband pumped by a high-brightness Tm-fiber laser at 1908 nm. The Ho:YAG SCF grown by the micro-pulling-down technique exhibits a propagation loss of $0.05\pm 0.005~\text{cm}^{-1}$ at $2.09~\unicode[STIX]{x03BC}\text{m}$ . A continuous-wave output power of 35.2 W is achieved with a slope efficiency of 42.7%, which is to the best of our knowledge the highest power ever reported from an SCF-based laser in the 2 $\unicode[STIX]{x03BC}\text{m}$ spectral range.

High power and energy generation in a Nd:YAG single-crystal fiber laser at 1834 nm

We report on a diode-end-pumped high-power and high-energy Nd:YAG single-crystal fiber laser at 1834 nm. Two 808 nm diodes injecting about 58 W pump power into the Nd:YAG fiber have generated 3.28 W continuous-wave and 1.66 W Cr:ZnSe-based passively Q-switched lasers. Slope efficiencies with respect to pump powers are 8.7% for the continuous-wave laser and 4.9% for the Q-switched laser. The extracted maximum pulse energy is about 266.9 μJ, and the corresponding maximum pulse peak power is 2.54 kW. These performances greatly surpass previous results regarding this specific laser emission because the laser gain medium in the form of fiber can significantly mitigate thermally induced power saturation thanks to its significantly reduced thermal lensing effect. Single-crystal fiber lasers show great potential for high average power, pulse energy, and peak power.

High-performance Ho:YAG single-crystal fiber laser in-band pumped by a Tm-doped all-fiber laser.

We report on, to the best of our knowledge, the first Q-switched single-crystal fiber (Ho:YAG SCF) laser in the 2μm spectral range, in-band pumped by a Tm-doped all-fiber laser. A continuous-wave laser with 12.5W output power and Q-switched laser with 1.44mJ pulse energy and 7.5ns pulse duration at a repetition rate of 1kHz were demonstrated. The high laser performance is attributed to the high gain, suppressed nonlinear effects, and easy thermal management which benefited from the unique geometric construction of the SCF.

Deep-UV 236.5 nm laser by fourth-harmonic generation of a single-crystal fiber Nd:YAG oscillator.

We demonstrate a deep-UV laser at 236.5nm based on extracavity fourth-harmonic generation of a Q-switched Nd:YAG single-crystal fiber laser at 946nm. We first compare two nonlinear crystals available for second-harmonic generation: LBO and BiBO. The best results at 473nm are obtained with a BiBO crystal, with an average output power of 3.4W at 20kHz, corresponding to a second-harmonic generation efficiency of 38%. This blue laser is frequency-converted to 236.5nm in a BBO crystal with an overall fourth-harmonic generation yield of 6.5%, corresponding to an average output power of 600mW at 20kHz. This represents an order of magnitude increase in average power and energy compared to previously reported pulsed lasers at 236.5nm. This work opens the possibility of LIDAR detection of dangerous compounds for military or civilian applications.

Mode-locked operation of Cr^4+:YAG single-crystal fiber laser with external cavity

We report what is to our knowledge the first mode-locked Cr⁴⁺:YAG single-crystal fiber laser, which generates pulses of 120-fs duration with an output power of 23 mW at a center wavelength of 1520 nm for a single pulse in a cavity-round-trip. The laser contains a single-crystal fiber multi-mode waveguide about 120 μm in diameter and 40-mm long. The fundamental transverse mode is selected with an external cavity. This design strategy turned out to be well suited for direct high-power-laser-diode pumping.

250 W single-crystal fiber Yb:YAG laser

We demonstrate an Yb:YAG single-crystal fiber laser with 251 W output power in continuous-wave and an optical efficiency of 44%. This performance can be explained by the high overlap between pump and signal beams brought by the pump guiding and by the good thermal management provided by the single-crystal fiber geometry. The oscillator performance with a reflectivity of the output coupler as low as 20% also shows high potential for power amplification.

34 W continuous wave Nd:YAG single crystal fiber laser emitting at 946 nm

Taking advantage of the pump beam confinement and the excellent thermal management offered by Nd:YAG single crystal fibers, we demonstrated a maximum output power of 34 W at 946 nm for an incident pump power of 86 W. A high slope efficiency of 53% was obtained. There was no rollover observed in the efficiency curves and the maximum output power was only limited by the available pump power.

Nd:YAG single-crystal fiber laser: Room-temperature cw operation using a single LED as an end pump

cw laser action has been obtained using as-grown single-crystal Nd:YAG fibers end-pumped by a single high-radiance LED. The fibers were 0.5 cm long and 80 μm in diameter, and the diameter of the LED luminous area was 85 μm. The lowest cw laser threshold was observed at a diode drive current of 45 mA.