- Special Issue
- Optical Methods for Life Sciences
- 3 Article (s)
Q-switched fiber laser using carbon platinum saturable absorber on side-polished fiber
H. Ahmad, H. Hassan, R. Safaei, K. Thambiratnam, and I. S. Amiri
A 1550 nm Q-switched fiber laser using a carbon platinum saturable absorber deposited on side-polished fiber (SPF) is proposed and demonstrated. The SPF is approximately 2 mm with a polarization-dependent loss (PDL) of 0.4 dB and an insertion loss of 2.5 dB. A stable Q-switched output spectrum is obtained at 1559.34 nm with a peak power of ～6 mW, a pulse width of 1.02 μs, pulse energy of 5.8 nJ, average output power of 0.76 mW, and a repetition rate of 131.6 kHz taken at a pump power of 230.0 mW. A signal-to-noise ratio of 49.62 dB indicates that the Q-switched pulse is highly stable. A 1550 nm Q-switched fiber laser using a carbon platinum saturable absorber deposited on side-polished fiber (SPF) is proposed and demonstrated. The SPF is approximately 2 mm with a polarization-dependent loss (PDL) of 0.4 dB and an insertion loss of 2.5 dB. A stable Q-switched output spectrum is obtained at 1559.34 nm with a peak power of ～6 mW, a pulse width of 1.02 μs, pulse energy of 5.8 nJ, average output power of 0.76 mW, and a repetition rate of 131.6 kHz taken at a pump power of 230.0 mW. A signal-to-noise ratio of 49.62 dB indicates that the Q-switched pulse is highly stable.
Chinese Optics Letters
- Publication Date: Sep. 10, 2017
- Vol. 15, Issue 9, 090601 (2017)
High temperature-sensitivity sensor based on long period fiber grating inscribed with femtosecond laser transversal-scanning method
Xinran Dong, Zheng Xie, Yuxin Song, Kai Yin, Dongkai Chu, and Ji’an Duan
We propose a high temperature-sensitive long period fiber grating (LPFG) sensor fabricated by using the femtosecond laser transversal-scanning method. The femtosecond pulses scan over the whole fiber core and some part of the cladding region; the modified regions are more extended. It is found that the LPFG-I fabricated by the transversal-scanning method shows higher temperature sensitivity and better temperature uniformity than that of LPFG-II written by the femtosecond laser point-by-point method. The LPFG-I with a temperature sensitivity of 75.96 pm/°C in the range of 25°C–400°C is measured. Moreover, in the range from 400°C to 800°C, a higher temperature sensitivity of 148.64 pm/°C and good linearity of 0.99 are achieved, while the temperature sensitivity of LPFG-II is only 95.55 pm/°C. LPFG-I exhibits better temperature characteristics, which, to the best of our knowledge, has the highest sensitivity in silica fiber temperature sensors. We propose a high temperature-sensitive long period fiber grating (LPFG) sensor fabricated by using the femtosecond laser transversal-scanning method. The femtosecond pulses scan over the whole fiber core and some part of the cladding region; the modified regions are more extended. It is found that the LPFG-I fabricated by the transversal-scanning method shows higher temperature sensitivity and better temperature uniformity than that of LPFG-II written by the femtosecond laser point-by-point method. The LPFG-I with a temperature sensitivity of 75.96 pm/°C in the range of 25°C–400°C is measured. Moreover, in the range from 400°C to 800°C, a higher temperature sensitivity of 148.64 pm/°C and good linearity of 0.99 are achieved, while the temperature sensitivity of LPFG-II is only 95.55 pm/°C. LPFG-I exhibits better temperature characteristics, which, to the best of our knowledge, has the highest sensitivity in silica fiber temperature sensors.
Chinese Optics Letters
- Publication Date: Sep. 10, 2017
- Vol. 15, Issue 9, 090602 (2017)
Frequency-doubled triangular shape lightwave generation with a flexible modulation index
Jing Li, Ze Hao, Li Pei, Tigang Ning, and Jingjing Zheng
An approach for full duty frequency-doubled triangle shape lightwave generation is proposed and demonstrated. It requires a dual-parallel Mach–Zehnder modulator (DP-MZM) driven by a sinusoidal signal. A stop band filter is coupled to filter out two undesired sidebands. By tuning the bias voltage applied to the DP-MZM, the output optical intensity with a full duty cycle triangle shape profile can be obtained. It is found that the required modulation index is no longer a fixed one. It can vary within a range, without degrading the target waveform. The principle is analyzed by theory and evaluated by simulation. A proof-of-concept experiment is also conducted. Good agreements between theoretical prediction and experimental results have been found. This approach might be attractive due to the feature of a variable modulation index, which insures simple operation in practice. An approach for full duty frequency-doubled triangle shape lightwave generation is proposed and demonstrated. It requires a dual-parallel Mach–Zehnder modulator (DP-MZM) driven by a sinusoidal signal. A stop band filter is coupled to filter out two undesired sidebands. By tuning the bias voltage applied to the DP-MZM, the output optical intensity with a full duty cycle triangle shape profile can be obtained. It is found that the required modulation index is no longer a fixed one. It can vary within a range, without degrading the target waveform. The principle is analyzed by theory and evaluated by simulation. A proof-of-concept experiment is also conducted. Good agreements between theoretical prediction and experimental results have been found. This approach might be attractive due to the feature of a variable modulation index, which insures simple operation in practice.
Chinese Optics Letters
- Publication Date: Sep. 10, 2017
- Vol. 15, Issue 9, 090603 (2017)
Chinese Optics Letters (COL) invites original manuscript submissions for a Special Issue on Optical Methods for Life Sciences to be published in September 2017. This issue will focus on the cutting-edge optical techniques and its applications to brain sciences and immunology. Understanding the brain’s function and brain diseases has long been quested. Brain’s function depends on neuronal networks and therefore from a systems biology perspective, should be studied not only at the neuron level,but also at the neuronal networks and system levels. Optical imaging can be applied at multiple levels from gene to molecular, from cellular to tissue and from organ to system levels to yield critical information bridging molecular structure and physiological function. Along with the brain research, immunology attracts many researchers’ interest. Optical methods enable visualizing cellular and molecular events dynamically and thus serve as ideal tools for studying immune activities in vivo.
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