Stable multiwavelength Tm‐doped fiber laser with a microfiber knot resonator

Abstract

We presented a compact and enduring multiwavelength Tm‐doped fiber laser at 2 μm employing a microfiber knot resonator (MKR). The MKR, made by the flame‐brushing technique, has a fiber diameter of 10 μm and a ring diameter of 150 μm. The MKR plays a role as both the comb filter and the power equalization device, which is critical for the stable multiwavelength Tm‐doped fiber laser. By properly adjusting the pump power, three wavelength lasing channels (1956.2, 1964.4, and 1971.8 nm) were observed stable and their average power density was around −8.76 dBm with 1 W pump power. In addition, the channel spacing is 5.8 nm with the 3‐dB bandwidth of the channel smaller than 0.5 nm. The experiments demonstrated that the MKR can be utilized as a comb filter with the suitable transmission spectrum to reach a steady multiwavelength Tm‐doped fiber laser.

Models and Programs of the Gain and Noise Figure of the Nd-doped Fiber Amplifier in 1.7-1.8μm Band

“…Only three outer energy levels: 4 I 9/2 , 4 I 15/2 , and 4 F 3/2 , are shown in the simplified energy level model of Nd 3+ , which is convenient to analyze. To amplify the signal light with the energy between 4 I 9/2 and 4 I 15/2 , which equals to 6E+03 cm -1 , a pump light with energy equal to the energy gap between 4 I 15/2 and 4 F 3/2 must be emitted into the working medium of Nd 3+ -ion-doped glass, then absorbed by the electrons in the ground state 4 I 9/2 [1][2][3][4][5][6]. The electrons stimulated by the pump light with energy that fulfills the gap between the ground state and excited state will experience stimulated absorption and be excited up to the excited state 4 F 3/2 .…”

“…The Nd element is white silver metal and one of the most active rare earth metals [1][2][3].The first fiber amplifier that appeared in 1961 used neodymium ion-doped fiber with a core diameter of 300μm and length of 1m as the gain medium and outputs laser with a wavelength of 1.06μm. A multiwavelength Tm-doped fiber laser was proposed with a microfiber knot resonator to filter signals of specific wavelengths and equalize the power [4]. A Tm-doped fiber amplifier with a ring-cavity configuration was also introduced, showing high efficiency and increasing output power [5].Researchers discussed the application and potential of Nd-doped fiber amplifiers [6].…”

“…An Nd-doped fiber amplifier has the advantages of low pumping threshold, low noise figure, and high doping concentration [7]. In recent years, it has been widely paid attention to in space communication and large-power amplification [4,5,[7][8][9][10][11][12][13][14][15][16][17][18][19][20][21].…”

Research on acoustic sensing device based on microfiber knot resonator

“…It can be widely used in some micro-nano optical devices. Such as lasers [4,5], sensors [6], micro-nano gratings [7], which have become an indispensable part of micro-nano optical devices. At present, optical fiber is the most commonly used acoustic sensor.…”