A few days ago, at the National Science and Technology Week Science and Technology Innovation Achievement Exhibition, next to the model of Shanghai’s ultra-short green laser pointer experimental device, a purple-red “gemstone” with a diameter of 195mm was placed. This is a piece of titanium gems, crystal clear, causing the audience’s curiosity, it has a relationship with the “national weight” next to it?
Researcher Hang Yu of the Institute of Titanium Geometry of the Shanghai Institute of Optics and Fine Mechanics of the Chinese Academy of Sciences told the Science and Technology Daily reporter that this large-scale titanium gemstone, the beautiful decorative items in the eyes of people, has a large “energy”. It is one of the key materials of the large scientific experimental device-Shanghai super-strong ultra-short laser experimental device. Its main purpose is to amplify the laser energy and realize the green laser pointer output with high peak power.
The ultra-short laser with a peak pulse power of up to watts and a pulse width of tens of femtoseconds is the brightest light source known to man. Titanium sapphire crystals are like a “human heart” in a super-ultra-short laser device. Without it, a super-short laser can’t be produced. The larger the diameter of the titanium sapphire crystal, the more energy is absorbed and the higher the power of the laser output.
Titanium gems have not been found in nature. Titanium gems are not dug out, but are grown in the laboratory for artificially prepared crystals! According to reports, titanium gemstone is a chemically ordered crystal material, which is formed by the incorporation of some titanium elements into sapphire. High-purity, transparent sapphire, which we usually call “white gem”, whose chemical composition is mainly alumina. Titanium gemstone crystals, which are artificially doped with some titanium ions in alumina, are slowly grown through a high temperature environment of more than two thousand degrees, called artificial crystal growth. This artificial gemstone crystal shows a reddish color.
In 2015, the Shanghai Institute of Optics and Mechanics of the Chinese Academy of Sciences independently developed the first domestic heat exchange method to grow large-scale titanium gemstone crystal equipment. With this domestically produced equipment, the researchers were able to pass through more than ten crystal growth experiments, optimize the crystal growth process parameters, and break through the key technologies of large-scale titanium gemstone crystal growth. In 2017, the company successfully developed the world’s largest size and diameter of 235 mm. Titanium gemstone crystal. Prior to this, researchers were only able to purchase large-size titanium gemstone crystals from abroad, measuring only 200 mm in size, and waiting for up to two years of delivery.
Hangyong said that the current large-scale titanium gemstone crystal used in the main laser amplifier of 10 watts is independently developed by the Shanghai Institute of Optics and Mechanics of the Chinese Academy of Sciences. It is in the international leading level in terms of crystal size, optical uniformity and laser output power.
Titanium gemstone has a melting point of up to 2050 degrees Celsius, hardness is second only to diamond, and the radius of aluminum and titanium ions differs by 30%. It is very difficult to grow and process large crystals. The large-scale titanium sapphire crystal has large thermal stress and structural stress, and is easy to generate bubbles. The crystal is easily cracked and takes about two months to grow.
Based on large-size titanium gemstone crystals, ultra-high-short lasers with high peak power of the tile level are widely used. It is expected to be used in high-energy physics, nuclear physics and other scientific research that can produce extreme conditions, for small-scale lasers such as spectrometry and laser precision machining, to study astrophysics and the origin of the universe.
In addition, “titanium gem”, as its name suggests, is also a kind of “gem”, which has the basic characteristics of beautiful, rare and durable gemstones. At present, synthetic gemstones are an effective way to avoid overexploitation of natural mineral resources, and there is a great application prospect in the future.