The second harmonic generation (SHG) is a second-order nonlinear process, and is being developed as a three-dimensional optical imaging technology in recent years. It is with unique high spatial resolution and high imaging depth as nonlinear optical imaging does, and can avoid the fluorescence bleaching effect in two-photon imaging.

Compared with other imaging techniques, SHG has unique imaging characteristics, which makes it widely used in many fields.

1. Increase SNR and three-dimensional spatial resolution

2. Long time imaging for sample

3. Deeper imaging can be done

4. Sample dyeing is not necessary

5. Highly sensitive to organizational symmetry changes

Schematic diagram and principle of harmonic imaging (SHG/THG)：

SHG for MoS2 crystal layer analysis
　

SHG for Bio-medical imaging

Helping to build a second harmonic imaging test system with minimum cost

To set up an ideal harmonic imaging system, a high-performance ultrafast laser is essential. In recent years, the rapid development of ultra-fast fiber laser has greatly promoted the research and application of SHG imaging technology. Compared with traditional Ti:Sapphire lasers, ultra-fast fiber lasers are favored by the market for their compact structure, small size, superior performance and comparatively lowered price.

The Rainbow1064/1550 developed by NPI Lasers is a cost-effective ultra-fast mode-locked fiber laser. Due to its high stable wavelength and power output, as well as its high reliability, it can meet the requirements of scientific research users for different material studies.

Applications：
 

Wang Xinran research group of Nanjing University

Hao Yufeng research group of Nanjing University