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Lasers, Optical Amplifiers, and Laser Optics|158 Article(s)
Mid-infrared SESAM mode-locked Er:CaF2-SrF2 bulk laser at 2.73 µm
Jingjing Liu, Linxuan Tang, Xiaoyue Feng, Mengyu Zong, Luyang Tong, Zhen Zhang, Lina Zhao, Jie Liu, and Liangbi Su
To the best of our knowledge, this is the first time that a mid-infrared Er3+:CaF2-SrF2 laser has achieved continuous-wave mode-locked operation by a semiconductor saturable absorber mirror. The laser emits a maximum output power of 93 mW at 2.73 µm with a repetition rate of approximately 69 MHz and demonstrates a high signal-to-noise ratio of around 71 dB. In addition, a MgF2 birefringent plate was utilized to enable wavelength tuning of the Er3+:CaF2-SrF2 laser, resulting in operation at approximately 2.73 µm, 2.75 µm, 2.79 µm, and 2.81 µm. These results demonstrate that Er3+:CaF2-SrF2 is a promising alternative for the generation of efficient diode-pumped mode-locked lasers around 2.8 µm. To the best of our knowledge, this is the first time that a mid-infrared Er3+:CaF2-SrF2 laser has achieved continuous-wave mode-locked operation by a semiconductor saturable absorber mirror. The laser emits a maximum output power of 93 mW at 2.73 µm with a repetition rate of approximately 69 MHz and demonstrates a high signal-to-noise ratio of around 71 dB. In addition, a MgF2 birefringent plate was utilized to enable wavelength tuning of the Er3+:CaF2-SrF2 laser, resulting in operation at approximately 2.73 µm, 2.75 µm, 2.79 µm, and 2.81 µm. These results demonstrate that Er3+:CaF2-SrF2 is a promising alternative for the generation of efficient diode-pumped mode-locked lasers around 2.8 µm.
Chinese Optics Letters
- Publication Date: May. 17, 2024
- Vol. 22, Issue 5, 051406 (2024)
Polarization full feedback external cavity of open loop spectral beam combining based on multi-single emitters laser diode
Man Hu, Weiqiao Zhang, Peng Cao, Tongtong Li, Xuyan Zhou, and Wanhua Zheng
In this paper, a spectral beam combining (SBC) structure of multi-single emitters laser diode based on a polarization full feedback (PFF) external cavity is proposed and demonstrated. The maximum combining efficiency is 75.6%, which leads to an output power of 38.48 W, a degree of polarization (DOP) of 99.42%, and electro-optical conversion efficiency of 35.63% under continuous wave operation at a current of 8 A. Compared to the conventional SBC, the output power, the combining efficiency, the electro-optical conversion efficiency, and the DOP of the PFF-SBC structure present improvements of 5.73 W, 11.26 percentage points, 5.3 percentage points, and 7.26 percentage points, respectively. The results show that this SBC method can achieve a high efficiency and linearly polarized laser output of SBC, thereby making the subsequent polarization beam-combining efficiency approach the limit. In this paper, a spectral beam combining (SBC) structure of multi-single emitters laser diode based on a polarization full feedback (PFF) external cavity is proposed and demonstrated. The maximum combining efficiency is 75.6%, which leads to an output power of 38.48 W, a degree of polarization (DOP) of 99.42%, and electro-optical conversion efficiency of 35.63% under continuous wave operation at a current of 8 A. Compared to the conventional SBC, the output power, the combining efficiency, the electro-optical conversion efficiency, and the DOP of the PFF-SBC structure present improvements of 5.73 W, 11.26 percentage points, 5.3 percentage points, and 7.26 percentage points, respectively. The results show that this SBC method can achieve a high efficiency and linearly polarized laser output of SBC, thereby making the subsequent polarization beam-combining efficiency approach the limit.
Chinese Optics Letters
- Publication Date: May. 14, 2024
- Vol. 22, Issue 5, 051405 (2024)
Suppression of nanosecond prepulses from regenerative amplifier and multipass amplifiers in the SULF-1PW laser
Peile Bai, Zongxin Zhang, Xinliang Wang, Jiayi Qian, Jiacheng Zhu, Fenxiang Wu, Jiabing Hu, Xiaojun Yang, Jiayan Gui, Xiaoming Lu, Yanqi Liu, Yi Xu, Xiaoyan Liang, Yuxin Leng, and Ruxin Li
In this research, we report the latest progress in the suppression of nanosecond prepulses from regenerative amplifier and multipass amplifiers in the SULF-1PW laser. The prepulse generated from the Pockels cell (PC) in a regenerative amplifier is delay-shifted by enlarging the distance between the PC and the nearby cavity mirror, and then removed by the extra pulse pickers outside the regenerative amplifier. The prepulses arising from multipass amplifiers are also further suppressed by adopting a novel amplifier configuration and properly rotating the Ti:sapphire crystals. After the optimizations, the temporal contrast on a nanosecond time scale is promoted to be better than a contrast level of 10-9. This research can provide beneficial guidance for the suppression of nanosecond prepulses in the high-peak-power femtosecond laser systems. In this research, we report the latest progress in the suppression of nanosecond prepulses from regenerative amplifier and multipass amplifiers in the SULF-1PW laser. The prepulse generated from the Pockels cell (PC) in a regenerative amplifier is delay-shifted by enlarging the distance between the PC and the nearby cavity mirror, and then removed by the extra pulse pickers outside the regenerative amplifier. The prepulses arising from multipass amplifiers are also further suppressed by adopting a novel amplifier configuration and properly rotating the Ti:sapphire crystals. After the optimizations, the temporal contrast on a nanosecond time scale is promoted to be better than a contrast level of 10-9. This research can provide beneficial guidance for the suppression of nanosecond prepulses in the high-peak-power femtosecond laser systems.
Chinese Optics Letters
- Publication Date: May. 17, 2024
- Vol. 22, Issue 5, 051404 (2024)
Dual-comb soliton rains based on polarization multiplexing in a single-walled carbon nanotube mode-locked Er-doped fiber laser
Yue Zhao, Ying Qin, Kailin Jia, Li Chen, Guangwei Chen, Guoqing Hu, Tengfei Wu, Huiyu Li, Jingwen He, and Zhehai Zhou
We experimentally demonstrate tunable dual-comb soliton rains in a polarization multiplexing fiber laser based on a single-walled carbon nanotube. The repetition frequency difference of dual-comb pulses is about 39 Hz, with a maximum extinction ratio of 29 dB. With suitable polarization states, one of the dual-comb pulses switches into soliton rain sequence with chirped isolating soliton trains. The signal-to-noise ratio reaches 61 dB, which is 11 dB higher than that of the normal dual-comb pulses. The intervals between chirped isolating solitons are distributed progressively, and the number of isolating solitons can be flexibly tuned from 2 to 11 by adjusting polarization state or pump power. Our work will provide support for further understanding of interaction dynamics of solitons and give a new route to the application of precision measurement. We experimentally demonstrate tunable dual-comb soliton rains in a polarization multiplexing fiber laser based on a single-walled carbon nanotube. The repetition frequency difference of dual-comb pulses is about 39 Hz, with a maximum extinction ratio of 29 dB. With suitable polarization states, one of the dual-comb pulses switches into soliton rain sequence with chirped isolating soliton trains. The signal-to-noise ratio reaches 61 dB, which is 11 dB higher than that of the normal dual-comb pulses. The intervals between chirped isolating solitons are distributed progressively, and the number of isolating solitons can be flexibly tuned from 2 to 11 by adjusting polarization state or pump power. Our work will provide support for further understanding of interaction dynamics of solitons and give a new route to the application of precision measurement.
Chinese Optics Letters
- Publication Date: May. 14, 2024
- Vol. 22, Issue 5, 051402 (2024)
Large aperture disk standing-wave unstable resonator with intra-cavity adaptive correction
Yi Yu, Jiayu Yi, Liu Xu, Jianli Shang, Jing Wu, Lixin Tong, Qingsong Gao, Chun Tang, Wei Zhang, and Lei Chen
An unstable resonator with seven large aperture ceramic disks and intra-cavity adaptive correction is presented. The composite ceramic disks with absorption rings were adopted to suppress amplified spontaneous emission. An intra-cavity aberration non-conjugate correction based on round-trip wavefront and relaxation iteration was applied in the resonator. After tilt and defocus were corrected in turn, an average output power of 4.5 kW was obtained. The corresponding beam quality factor β was 19.5. After tilt, defocus, and high order aberrations were corrected, the average output power was increased to 5.4 kW, and the beam quality factor β was improved to 6.8. An unstable resonator with seven large aperture ceramic disks and intra-cavity adaptive correction is presented. The composite ceramic disks with absorption rings were adopted to suppress amplified spontaneous emission. An intra-cavity aberration non-conjugate correction based on round-trip wavefront and relaxation iteration was applied in the resonator. After tilt and defocus were corrected in turn, an average output power of 4.5 kW was obtained. The corresponding beam quality factor β was 19.5. After tilt, defocus, and high order aberrations were corrected, the average output power was increased to 5.4 kW, and the beam quality factor β was improved to 6.8.
Chinese Optics Letters
- Publication Date: May. 14, 2024
- Vol. 22, Issue 5, 051401 (2024)
Design of a high frequency accuracy heterodyne laser source working in a wide temperature range
Hongxing Yang, Yan Wang, Ziqi Yin, Pengcheng Hu, Ruitao Yang, and Jing Li
To ensure the frequency accuracy of a heterodyne laser source in the ambient temperature range of -20°C to 40°C, a dual-longitudinal-mode thermally stabilized He–Ne laser based on non-equilibrium power locking was designed. The ambient adaptive preheating temperature setting scheme ensured the laser could operate normally in the range of -20°C to 40°C. The non-equilibrium power-locked frequency stabilization scheme compensated for the frequency drift caused by different stabilization temperatures. The experimental results indicated that the frequency accuracy of the laser designed in this study could reach 5.2 × 10-9 in the range of -20°C to 40°C. To ensure the frequency accuracy of a heterodyne laser source in the ambient temperature range of -20°C to 40°C, a dual-longitudinal-mode thermally stabilized He–Ne laser based on non-equilibrium power locking was designed. The ambient adaptive preheating temperature setting scheme ensured the laser could operate normally in the range of -20°C to 40°C. The non-equilibrium power-locked frequency stabilization scheme compensated for the frequency drift caused by different stabilization temperatures. The experimental results indicated that the frequency accuracy of the laser designed in this study could reach 5.2 × 10-9 in the range of -20°C to 40°C.
Chinese Optics Letters
- Publication Date: Apr. 25, 2024
- Vol. 22, Issue 4, 041407 (2024)
1.6-µm single-frequency erbium-doped fiber laser based on two cascaded subrings
Yaqi Zhai, Han Wen, Haowei Chen, Baole Lu, and Jintao Bai
We demonstrate a stable narrow linewidth single-frequency erbium-doped fiber laser (EDFL) operating at 1.6 µm. A Fabry–Perot fiber Bragg grating and two cascaded subrings are incorporated in the main ring cavity to achieve single-frequency operation. The experimentally measured optical signal-to-noise ratio is greater than 73 dB. Furthermore, the linewidth of the EDFL is measured to be about 480 Hz by the self-built short-delayed self-heterodyne interferometry device. The laser shows superior stability, with no mode-hopping during the 60-min observation period. The proposed EDFL provides a new experimental idea for realizing a single-frequency fiber laser in the L-band. We demonstrate a stable narrow linewidth single-frequency erbium-doped fiber laser (EDFL) operating at 1.6 µm. A Fabry–Perot fiber Bragg grating and two cascaded subrings are incorporated in the main ring cavity to achieve single-frequency operation. The experimentally measured optical signal-to-noise ratio is greater than 73 dB. Furthermore, the linewidth of the EDFL is measured to be about 480 Hz by the self-built short-delayed self-heterodyne interferometry device. The laser shows superior stability, with no mode-hopping during the 60-min observation period. The proposed EDFL provides a new experimental idea for realizing a single-frequency fiber laser in the L-band.
Chinese Optics Letters
- Publication Date: Apr. 26, 2024
- Vol. 22, Issue 4, 041406 (2024)
5 kW-level single-mode fiber amplifier based on low-numerical-aperture fiber
Yisha Chen, Yun Ye, Liangjin Huang, Huan Yang, Hanshuo Wu, Zhiping Yan, Zhiyong Pan, Xiaolin Wang, Zefeng Wang, and Pu Zhou
A low-numerical-aperture (NA) concept enables large-mode-area fiber with better single-mode operation ability, which is beneficial for transverse mode instability and nonlinear effects suppression. In this contribution, we reported a high-power fiber amplifier based on a piece of self-developed large-mode-area low-NA fiber with a core NA of 0.049 and a core/inner cladding diameter of 25/400 µm. The influence of the pump wavelength and fiber length on the power scaling potential of the fiber amplifier is systematically investigated. As a result, an output of 4.80 kW and a beam quality factor of ∼1.33 were finally obtained, which is the highest output power ever reported in a fiber amplifier exploiting the low-NA fiber. The results reveal that low-NA fibers have superiority in power scaling and beam quality maintenance at high power levels. A low-numerical-aperture (NA) concept enables large-mode-area fiber with better single-mode operation ability, which is beneficial for transverse mode instability and nonlinear effects suppression. In this contribution, we reported a high-power fiber amplifier based on a piece of self-developed large-mode-area low-NA fiber with a core NA of 0.049 and a core/inner cladding diameter of 25/400 µm. The influence of the pump wavelength and fiber length on the power scaling potential of the fiber amplifier is systematically investigated. As a result, an output of 4.80 kW and a beam quality factor of ∼1.33 were finally obtained, which is the highest output power ever reported in a fiber amplifier exploiting the low-NA fiber. The results reveal that low-NA fibers have superiority in power scaling and beam quality maintenance at high power levels.
Chinese Optics Letters
- Publication Date: Apr. 18, 2024
- Vol. 22, Issue 4, 041404 (2024)
High-power all-fiber linearly polarized Yb-doped chirped pulse amplifier based on active polarization control
Tao Wang, Shuai Ren, Hongxiang Chang, Bo Ren, Kun Guo, Can Li, Pengfei Ma, Jinyong Leng, and Pu Zhou
High-power ultrafast laser amplification based on a non-polarization maintaining fiber chirped pulse amplifier is demonstrated. The active polarization control technology based on the root-mean-square propagation (RMS-prop) algorithm is employed to guarantee a linearly polarized output from the system. A maximum output power of 402.3 W at a repetition rate of 80 MHz is realized with a polarization extinction ratio (PER) of > 11.4 dB. In addition, the reliable operation of the system is verified by examining the stability and noise properties of the amplified laser. The M2 factor of the laser beam at the highest output power is measured to be less than 1.15, indicating a diffraction-limited beam quality. Finally, the amplified laser pulse is temporally compressed to 755 fs with a highest average power of 273.8 W. This is the first time, to the best of our knowledge, that the active polarization control technology was introduced into the high-power ultrafast fiber amplifier. High-power ultrafast laser amplification based on a non-polarization maintaining fiber chirped pulse amplifier is demonstrated. The active polarization control technology based on the root-mean-square propagation (RMS-prop) algorithm is employed to guarantee a linearly polarized output from the system. A maximum output power of 402.3 W at a repetition rate of 80 MHz is realized with a polarization extinction ratio (PER) of > 11.4 dB. In addition, the reliable operation of the system is verified by examining the stability and noise properties of the amplified laser. The M2 factor of the laser beam at the highest output power is measured to be less than 1.15, indicating a diffraction-limited beam quality. Finally, the amplified laser pulse is temporally compressed to 755 fs with a highest average power of 273.8 W. This is the first time, to the best of our knowledge, that the active polarization control technology was introduced into the high-power ultrafast fiber amplifier.
Chinese Optics Letters
- Publication Date: Apr. 17, 2024
- Vol. 22, Issue 4, 041403 (2024)
Eye-safe intra-cavity diamond cascaded Raman laser with high peak-power and narrow linewidth
Xiaobo Mi, Chaonan Lin, Yongsheng Hu, Houjie Ma, Jiuru He, Fengying Ma, Li Fan, and Chongxin Shan
The 1.4–1.8 µm eye-safe lasers have been widely used in the fields of laser medicine and laser detection and ranging. The diamond Raman lasers are capable of delivering excellent characteristics, such as good beam quality concomitantly with high output power. The intra-cavity diamond Raman lasers have the advantages of compactness and low Raman thresholds compared to the external-cavity Raman lasers. However, to date, the intra-cavity diamond cascaded Raman lasers in the spectral region of the eye-safe laser have an output power of only a few hundred milliwatts. A 1485 nm Nd:YVO4/diamond intra-cavity cascaded Raman laser is reported in this paper. The mode matching and stability of the cavity were optimally designed by a V-shaped folded cavity, which yielded an average output power of up to 2.2 W at a pulse repetition frequency of 50 kHz with a diode to second-Stokes conversion efficiency of 8.1%. Meanwhile, the pulse width of the second-Stokes laser was drastically reduced from 60 ns of the fundamental laser to 1.1 ns, which resulted in a high peak power of 40 kW. The device also exhibited single longitudinal mode with a narrow spectral width of < 0.02 nm. The 1.4–1.8 µm eye-safe lasers have been widely used in the fields of laser medicine and laser detection and ranging. The diamond Raman lasers are capable of delivering excellent characteristics, such as good beam quality concomitantly with high output power. The intra-cavity diamond Raman lasers have the advantages of compactness and low Raman thresholds compared to the external-cavity Raman lasers. However, to date, the intra-cavity diamond cascaded Raman lasers in the spectral region of the eye-safe laser have an output power of only a few hundred milliwatts. A 1485 nm Nd:YVO4/diamond intra-cavity cascaded Raman laser is reported in this paper. The mode matching and stability of the cavity were optimally designed by a V-shaped folded cavity, which yielded an average output power of up to 2.2 W at a pulse repetition frequency of 50 kHz with a diode to second-Stokes conversion efficiency of 8.1%. Meanwhile, the pulse width of the second-Stokes laser was drastically reduced from 60 ns of the fundamental laser to 1.1 ns, which resulted in a high peak power of 40 kW. The device also exhibited single longitudinal mode with a narrow spectral width of < 0.02 nm.
Chinese Optics Letters
- Publication Date: Apr. 18, 2024
- Vol. 22, Issue 4, 041402 (2024)
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