<p>We present a comparative study of continuous-wave (CW) and pulsed optical tweezers for trapping polystyrene beads with radii of 250&#xa0;nm, 500&#xa0;nm, and 1&#xa0;μm, using five different laser power settings. In this study we also emphasize the importance of using femtosecond laser, which uses intense peak power pulses to generate larger gradient forces than a CW laser at very low and same average power. We could also achieve stable trapping of 250&#xa0;nm particle at very low average powers of femtosecond laser. A Ti: Sapphire (MIRA 900&#xa0;F) laser, capable of seamlessly switching between CW and pulsed modes, was used to ensure identical experimental conditions for both cases. The trap strength in each mode was determined by fitting the power spectrum to a Lorentzian curve. Our results show that pulsed tweezers are more effective for smaller particles, while for larger particles, both CW and pulsed tweezers perform similarly at lower laser powers. However, as the power increases, pulsed tweezers provide more stable trapping.</p>

错误:搜索内容不能为空,请输入英文关键词
错误:关键词超出字数限制,请精简
高级检索

Comparative study of femtosecond and conventional optical tweezers

  • Ajitesh Singh,
  • Krishna Kant Singh,
  • Deepak Kumar,
  • Debabrata Goswami

摘要

We present a comparative study of continuous-wave (CW) and pulsed optical tweezers for trapping polystyrene beads with radii of 250 nm, 500 nm, and 1 μm, using five different laser power settings. In this study we also emphasize the importance of using femtosecond laser, which uses intense peak power pulses to generate larger gradient forces than a CW laser at very low and same average power. We could also achieve stable trapping of 250 nm particle at very low average powers of femtosecond laser. A Ti: Sapphire (MIRA 900 F) laser, capable of seamlessly switching between CW and pulsed modes, was used to ensure identical experimental conditions for both cases. The trap strength in each mode was determined by fitting the power spectrum to a Lorentzian curve. Our results show that pulsed tweezers are more effective for smaller particles, while for larger particles, both CW and pulsed tweezers perform similarly at lower laser powers. However, as the power increases, pulsed tweezers provide more stable trapping.