Ultrafast Thin Windows

Shalom EO’s ultrafast thin windows are critical ultrafast optics for transmitting femtosecond pulses with minimum losses. These thin windows are made of Fused Silica, manufactured with small thicknesses (standard 0.1mm~3mm thick). Our thin windows, available as off-the-shelf and custom windows, are offered in three standard coating configurations:

1. Uncoated blanks, the high-precision and high surface quality uncoated window substrates are excellent options for depositing other customized coatings;

2. 700-900nm AR coated, these windows are designed for 800nm Ti: Sapphire femtosecond lasers

3. 950-1100nm AR Coating, these windows are designed for 1030nm Ytterbium doped (Yb) lasers

Minimized geometric and surface profile deviation is achieved with wavefront distortion of λ/10@633nm and parallelism of <10 arcsec. Shalom EO’s ultrafast thin windows also feature a low group delay dispersion of GDD=±10fs2, which implies negligible phase distortion to the optical wavefront, leading to cleaner and more stable pulses in applications like pump-probe experiments or multiphoton imaging.

Specifications:

Interference Test Result (Measured by Zygo)

Femto-line laser systems are developing rapidly in recent years; subsequently, one of their most crucial components, the demand for Ultra-thin (typically 0.1mm, 0.2mm) windows or substrates with high surface flatness (Lambda/10 or Lambda/4 @633nm) is surging.

The classical single surface polishing method, though utilized conventionally and commonly in the production of high precision laser grade optics products,  practical implementation has proved its difficulty and unreliability while processing high flatness optics with miniature thickness. The reason is that, during the actual operation of classical single surface polishing, the polished optics are often put on a pitch plate to accomplish the polishing procedure; the pitch plate and the optic are often bonded, inducing stress to the optics. You might manage to attain high surface quality while the optic is on the pitch plate, but once the optic is detached, the stress that comes from bonding is naturally released, leading to a slight change in the form of the optics, and the surface flatness will eventually be lowered. The thinner the optics, the more severe the impact of stress-releasing, since even the mildest deviation of the surface flatness could be significant as a proportion of the total thickness. Achieving high surface flatness in ultra-thin windows is always challenging for manufacturers.

To deal with the problem, Hangzhou Shalom EO has successfully developed a double surface polishing method for processing high-precision optical windows or substrates, where both of the surfaces of optics complete their polishing procedure in one go. The optics are not put on pitch plates during the procedure, so there is no stress-releasing problem, which effectively eliminates the variation of surface flatness after it is taken off the pitch plates. The double surface polishing method was not incorporated in precise optics fabrication previously because the finished optics produced by this method have the defect of low surface quality (that is, relatively higher S/D). Hangzhou Shalom EO has overcome this obstacle by improving the polishing machine, successfully raising the surface quality, while exploiting the benefits of the double surface polishing method of precise surface flatness. Furthermore, excellent parallelism (10 arcsec) is also realized on the UVFS Ultra-thin Windows or Substrates.