Spider silk is a magical substance than silk. But because of the temporary human can not tame spiders, spider silk industrial production is only a dream for the time being. Moreover, although modern biotechnology has the ability to steal the day, it can not let the spider in addition to any creatures produce spider silk protein. So, the source of industrial spider silk can only rely on "wild" spider. The amount of less do not say, and this "manual" type of production can not control, there is no standard. So even if the collection of these wild spider silk, its production and application is also a problem. So how do you use these spider silk that are not compatible with modern means of production?

Recently, a team of researchers from India claimed to find a solution to this problem. They say that in a suitable environment, a protein in the spider silk can amplify the power of the laser pointer so that the laser gets enough power to cut or weld the spider silk. The principle behind this approach is called "nonlinear multiphoton absorption". In a simple sense, this effect allows two (or more) photons to be absorbed by matter as a photon, and the energy of the "photon" is the sum of the energy of the two (or more) photons. It is non-linear because the energy of the synthetic photon is equal to the square sum of the multi-photon intensity and can not be a fraction or a multiple.

This effect is important for materials that can absorb high energy photons but can not absorb low-energy photons (such as spider silk). Because it can cause the light that passes through the material normally, it can be absorbed by the material effectively, and the material molecules can transition to the highest energy level. At high energy levels, molecules can appear fluorescent, chemical bonds break, recombine, or continue to absorb energy into melting and other changes.

On spider silk, the researchers used a femtosecond green laser pointer (10-15 second length laser beam) to guide the energy to a specific location using the multiphoton absorption effect. They chose femtosecond, rather than the more common "long picosecond" (10-12 seconds), because in the femtosecond laser irradiation, the target site of energy can be stored only in the spider silk, and do not spread to other parts of the damage.

When using femtosecond lasers, the researchers found several wavelengths that allowed spider silk to achieve double, triple, or even quad single photon energy multiphoton absorption. Among them, 80GW (gigawatt) per square centimeter of power is the baseline, any less than the power of the laser can not produce any effect. And 300GW per square centimeter is on the line, in this power and above, the laser will only cut off the spider silk. Of course, this power laser can be used to accurately cut spider silk into various lengths.

As for the blue laser pointer between the two lines, the power can be successfully let the spider silk half melting, the volume slightly expanded lap; in the deviation from the center of the location, but also let the spider silk to bend. Through the control of the irradiation time, the researchers can precisely control the specific degree of bending. At present, they have used spider silk to make a successful spiral, spring, and complex knot.