• 한국레이저가공학회지
• /
• 제15권2호
• /
• pp.6-10
• /
• 2012

We fabricated the diffraction grating on the surface of fused silica glass using a femtosecond laser. The grooves of diffraction grating has a lot of micro crack and debris result in reduced diffraction efficiency. So, we polished the diffraction grating with $CO_2$ laser beam. With different scan number of $CO_2$ laser beam, we observed the image of diffraction grating and measured the diffraction efficiency.

• 한국레이저가공학회지
• /
• 제14권3호
• /
• pp.17-20
• /
• 2011

We fabricated a multi-layer diffraction grating inside fused silica glass by using a femtosecond laser direct writing method. The femtosecond laser with a wavelength of 515 nm, a pulse width of 250 fs, a repetition rate of 100 kHz, and an average output power of 6 W was used. Two layer diffraction grating with a grating period of $6{\mu}m$ was successfully fabricated with the layer gap of 0.5, 1, 2, 3, and $5{\mu}m$, respectively. Also, we investigated the diffraction pattern by illuminating a He-Ne laser beam. Finally, we demonstrated the diffraction grating with a grating period of $3{\mu}m$ by adjusting the gap of each layer with a grating period of $6{\mu}m$. Femtosecond laser direct writing technology of multi-layer has a potential to fabricate the diffraction grating with a grating period of below $1.5{\mu}m$.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2006년도 제37회 하계학술대회 논문집 C
• /
• pp.1428-1429
• /
• 2006

We investigated the diffraction efficiency, erasing property and rewriting property of diffraction grating with each wavelength of recording beam. A (P:P) polarized light was exposed on AsGeSeS and Ag/AsGeSeS thin film to form a diffraction grating by HeNe(635nm) laser and DPSS(532nm) laser. At the maximum efficiency condition, unpolarized HeNe laser beam was irradiated to erase 1ha generated diffraction grating. The HeNe laser showed more higher diffraction efficiency and the DPSS laser showed more faster diffraction grating time. At erasing and rewriting process, AsGeSeS(61%-85%)thin film showed better property than Ag doped Ag/AsGeSeS(53%-63%) double layer structured thin film.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2003년도 하계학술대회 논문집 Vol.4 No.2
• /
• pp.1058-1061
• /
• 2003

In this thesis, we observed the optical characteristic of amorphous chalcogenide thin films by He-Cd laser. Also, grating formation by He-Ne laser and He-Cd laser. After analyze diffraction efficiency of the time on the $Ag(200{\AA})/As_{40}Ge_{10}Se_{15}S_{35}$ thin films. The result diffraction efficiency of Maximun 0.2% reduced according to time grating formation by He-Ne laser. Diffraction efficiency of Maximun 0.1% showed stabiliy characteristic according to time grating formation by He-Cd laser.

• Current Optics and Photonics
• /
• 제2권2호
• /
• pp.125-133
• /
• 2018

We report an in-depth analysis of the design and fabrication of multilayer dielectric (MLD) diffraction gratings for spectral beam combining at a wavelength of 1055 nm. The design involves a near-Littrow grating and a modal analysis for high diffraction efficiency. A range of wavelengths, grating periods, and angles of incidence were examined for the near-Littrow grating, for the $0^{th}$ and $-1^{st}$ diffraction orders only. A modal method was then used to investigate the effect of the duty cycle on the effective indices of the grating modes, and the depth of the grating was determined for only the $-1^{st}$-order diffraction. The design parameters of the grating and the matching layer thickness between grating and MLD reflector were refined for high diffraction efficiency, using the finite-difference time-domain (FDTD) method. A high reflector was deposited by electron-beam evaporation, and a grating structure was fabricated by photolithography and reactive-ion etching. The diffraction efficiency and laser-induced damage threshold of the fabricated MLD diffraction gratings were measured, and the diffraction efficiency was compared with the design's value.

• 한국레이저가공학회지
• /
• 제9권3호
• /
• pp.1-5
• /
• 2006

Diffraction grating is the optical device which has periodic pattern. Decorative logotypes is the one of application of diffraction grating. In this paper diffraction grating for decorative logotype is fabricated by dot pattern in stead of line pattern. A metallic mold for diffraction gratings is fabricated with a mode-locked 12 ps Nd:YVO4 laser. Laser pulses with a wavelength of 355nm are irradiated on the surface of NOK 80, a mold material, to generate dot patterns. In order to minimize the dot diameter, laser power is set just above the ablation threshold of NOK 80. Results show that the spectrum from the fabricated mold is good enough for some industrial application

• 한국레이저가공학회:학술대회논문집
• /
• 한국레이저가공학회 2006년도 추계학술발표대회 논문집
• /
• pp.114-117
• /
• 2006

Diffraction grating is the optical device which has periodic pattern. Decorative logotypes is the one of application of diffraction grating. In this paper diffraction grating for decorative logotype is fabricated by dot pattern in stead of line pattern. A metallic mold for diffraction gratings is fabricated with a mode-locked 12 ps $Nd:YVO_4$ laser. Laser pulses with a wavelength of 355nm are irradiated on the surface of NOK 80, a mold material, to generate dot patterns. In order to minimize the dot diameter, laser power is set just above the ablation threshold of NOK 80. Results show that the spectrum from the fabricated mold is good enough for some industrial application.

• 한국정밀공학회지
• /
• 제27권3호
• /
• pp.18-26
• /
• 2010

Diffraction gratings with precise spatial periods of 2 ${\mu}m$ and 5 ${\mu}m$ have been fabricated by using a femtosecond laser which does not have limits on materials of micromachining and small thermal effects due to high peak power. Diffraction angle and diffraction efficiency of those were measured. Simulation results of diffraction angle and diffraction efficiency of the diffraction grating calculated with the parameters such as line width, depth, and spatial period of the fabricated gratings were compared with experimental results measured with a He-Ne laser. Besides these, Fresnel Zone Plates (FZPs) with focal distances of 50 mm and 25 mm were fabricated and focal distances of fabricated FZP were measured. Those experimental results for diffraction gratings and FZPs match well with experimental results.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2006년도 추계학술대회 논문집 전기물성,응용부문
• /
• pp.55-56
• /
• 2006

We investigated the diffraction grating efficiency by the DPSS laser beam wavelength to improve the diffraction efficiency on AsGeSeS & Ag/ AsGeSeS thin film. Diffraction efficiency was obtained from DPSS(532nm)(P:P)polarized laser beam on AsGeSeS, Ag/ AsGeSeS and AsGeSeS/Ag/AsGeSeS thin films. As a result, for the laser beam intensity, 0.24 mW, single AsGeSeS thin film shows the highest value of 0.161% diffraction efficiency at 300 s and for 2.4 mW, it was recorded with the fastest speed of 50 s, which the diffraction grating forming speed is faster than that of 0.24 mW beam. Ag/ AsGeSeS and AsGeSeS/ Ag/ AsGeSeS multi-layered thin film also show the faster grating forming speed at 2.4 mW and higher value of diffraction efficiency at 0.24 mW.

• 한국레이저가공학회:학술대회논문집
• /
• 한국레이저가공학회 2006년도 춘계학술발표대회 논문집
• /
• pp.97-100
• /
• 2006

Picosecond (ps) laser micro-machining has emerged as an attractive method of fabricating high-precision microstructures, especially in metals. In this paper, a metallic mold for diffraction gratings is fabricated with a mode-locked 12 ps $Nd:YVO_4$ laser. Laser pulses with a wavelength of 355nm are irradiated on the surface of NOK 80, a mold material, to generate line patterns. In order to minimize the line width, laser power is set just above the ablation threshold of NOK 80. Results show that the spectrum from the fabricated mold is good enough for some industrial application.