We report an invisible two-dimensional (2D) barcode embedded into a synthetic fused silica by femtosecond laser
processing using a computer-generated hologram (CGH) that generates a spatially extended femtosecond pulse beam in
the depth direction. When we illuminate the irradiated 2D barcode pattern with a 254 nm ultraviolet (UV) light, a strong
red photoluminescence (PL) is observed, and we can read it by using a complementary metal oxide semiconductor
(CMOS) camera and image processing technology. This work provides a novel barcode fabrication method by
femtosecond laser processing using a CGH and a barcode reading method by a red PL.
We report on a curved waveguide fabrication using femtosecond laser processing with a glass hologram. We design and
produce a glass hologram that transforms femtosecond laser beam into a half-ring beam. The half-ring beam generated
by the glass hologram is patterned inside fused silica with one laser shot. The guided light whose bending radius is larger
than 1mm is observed at wavelength of 635nm. As a simple application, a directional coupler consisting of a straight-line
waveguide and a half-ring waveguide is fabricated by two laser shots. Its basic functionality as a coupler is confirmed.
We also develop a hologram that simultaneously produces a straight-line and a half-ring. Using it, we demonstrate a
directional coupler fabrication inside crown glass with one laser shot.
In accordance with the development of various optical devices, an urgent need for innovative 3D microfabrication
method arises. It requires not only rapid processing time or high energy efficiency but also high flexibility in designing
3D structure. Hence we established new 3D microfabrication method to satisfy all of these seemingly-contradictory
factors. This method uses only single femtosecond laser pulse and phase CGH (computer generated hologram); the phase
distribution of the pulse is controlled by the CGH and an arbitrary 3D microstructure is fabricated inside transparent
material by multi photon absorption. It means that this method costs extremely short time and low power for the
fabrication of an arbitrary complex 3D microstructure. In this report, the microfabrication of 3D spiral array which
consists of 24 dot elements is demonstrated. It is very difficult to process multiple elements at different depths
simultaneously, because the light intensity depends on the numerical aperture number of the objective lens and the
distance from the CGH. Hence we improved the CGH calculation by considering these dependencies so that the light
intensity of each element could be controlled separately. By this intensity adjustment, the shape of all elements becomes
homogeneous. The other side of this intensity control is that it is able to process different shape elements intentionally by
varying the intensity of each element. This intensity control is confirmed by the microfabrication with another CGH
which forms 7 dot elements of different shapes. This result proves the high flexibility in designing 3D structure of this
We report on a new waveguide fabrication method with femtosecond laser pulses shaped by Computer-Generated
Hologram (CGH). We design and make CGH's that generates a straight-line intensity distribution from an input laser
intensity distribution. We fabricate a waveguide inside a fused silica sample with exposing the line intensity beam
generated by the CGH, without translating the sample. The fabricated waveguide is 5.1 mm long and 6μm width. We also observe guided-light passing through the waveguide that is butt-coupled to a single mode fiber, at wavelength of 635 nm. The near field pattern is nearly circular cross section. This is the first achievement of waveguide fabrication using a CGH.