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VAD-process Synthetic Fused Silica SK-1300

Our Company successfully developed synthetic fused silica SK-1300 as a result of significant improvements made to the conventional VAD (vapor-phase axial deposition) method of optical fiber manufacturing technology.

SK-1300 is extremely high in purity and much lower in OH content than the traditional direct method, thus making it the first synthetic fused silica usable in the semiconductor and liquid crystal display industries.

SK-1300 is the state-of-the-art technology in optical characteristics because it provides a high ultraviolet transmission, no micro inclusion and a solarization resistance, in addition to heat resistance, mechanical strength, and chemical resistance.

These products can be used in a wide variety of industrial applications for semiconductors, optical and all physical or chemical related research featuring these applications:

  • Wafers for various types of devices such as TFT(poly-Si thin-film transistor LCD.), SOI (Silicon on Insulator) etc.
  • Photomask substrates for ultra-LSI and LCD.
  • Reactor furnace tubes, jigs and tools for ULSI manufacturing processes.
  • Electrical-discharge lamp tubes.
  • Optical elements, Ienses, mirrors and windows, for ultraviolet and vacuum ultraviolet.

Typical Impurity Analysis


Element Analytical value Element Analyltcal value
Al <0.2 Co <0.01
Fe <0.5 Ni <1.0
Ti <0.1 P <1.0
Ca <0.5 B <0.01
Mg <0.1 Na <0.5
Mn <0.1 K <0.2
Cr <0.2 Li <0.1
Cu <0.2 Zr <0.1
OH <200    

Chemical Resistance

Solution Treatment temperatures(°C) & hours(H) Weight loss(mg/cm2)
H2O 95 45 0.0001-0.0002
1/100 N HNO3 115 24 0.005 -0.01
5% NaOH 100 10 1.35





Refractive Index

Wavelength(nm,in air)

25°C in air

20°C in air
365.015(i) 1.474710 1.474655
404.656(h) 1.469786 1.469731
435.835(g) 1.466860 1.466807
486.133(F) 1.463293 1.463240
546.075(e) 1.460245 1.460194
587.562(d) 1.458631 1.458580
656.273(c) 1.456535 1.456484

Measuring accuracy ±1×10-6

Wavelength(nm,in air)
25°C in air
365.015(i) 11.3
404.656(h) 11.0
435.835(g) 10.7
486.133(F) 10.5
546.075(e) 10.2
587.562(d) 10.3
656.273(c) 10.1

Measuring accuracy ±1×10-6


Optical Qualities

Item Grade
Bubbles 0~0.03mm2/100cm3
Striae Grade A in one direction (As per Mil-G-174)
Birefrengence (Strain) 10nm/cm and under
Fluorescence Not permitted (Excited wavelength 254nm)

Physical properties

Item Unit Value Item Unit Value
Density g/cm3 2.201 Coefficient of thermal expansion cm/cm°C 5.5×10-7
Young's module kg/mm2 7280      
Poisson's ratio   0.17 Softening point °C 1700
Compression strength kg/mm2 115 Annealing point °C 1160
Bending strength kg/mm2 7.0 Strain point °C 1060
Tensile strength kg/mm2 5.6      
Torsional rigidity kg/mm2 3150 Specific heat (26°C) cal/g°C 0.176
Vickers hardness kg/mm2 900-1030 Thermal conductivity ratio(26°C)
Knoop hardness kg/mm2 650-710 Thermal conductivity ratio(100°C) cal/cmsec°C 3.27×10-3