Generation of multiple parallel non-diffractive beams without any disruption of each beam is a challenging task. Here, we report the approach of spatial-spectral modulation for non-disruptive generation of Bessel beam array. Such modulation is realized with a simple beam splitter placed in a Fourier plane of the initial beam. The various designs of the beam-splitter phase mask allow to generate an array of the Bessel beams with various shapes and controlled intensity distribution without mutual interference of each beam. As such, this array formation can enhance quality of glass cutting and increase the throughput of micro-patterning of glass-fine mask required for a new generation high-resolution OLED display.
Requirements on glass manufacturing with exceptionally high mechanical strength triggered development of new laserbased processing methods. Localized modifications produced by ultrashort pulsed lasers are attractive but may lead to micro-crack generation in glass. Aiming to control stresses during volumetric material modifications, we have studied the effect of pulse duration experimentally. Bessel beam shapes with arbitrary conical angles have been generated using a programmable spatial light modulator (SLM), while stresses have been monitored using time-resolved optical transmission and cross polarized microscopy. Pulse duration variation influences mechanical stress in the laser glass interaction, and we found the optimized pulse duration exists in the laser glass machining by pump-probe microscopy.
Diffraction-free Bessel beams have been of great interest for laser processing of transparent materials. Compared to traditional Gaussian beams, the Bessel-Gauss beams has thin focus profile which remains invariant over much longer propagation distances. Achieved in such a way extended depth of focusing in combination with precise energy deposition has opened diverse promising applications in display industry. Here we have analyzed the effect of conical angle on the interaction of Bessel beam with a display panel having multiple organic and inorganic layers on a glass. First, we have shown that experimentally observed thermal damages in display emission area are caused by long Bessel beam tails in contrast to Gaussian beams, where the damages are driven by heat diffusion. Second, we study the role of Kerr effect and arising instabilities in non-linear propagation through the glass substrate. Using numerical simulations and in-situ pump-probe microscopy methods we gain the knowledge of primary steps of energy deposition with high temporal and spatial resolution. At high laser intensities and low numerical aperture, the original Bessel beam profile can be de-stabilized leading to the longitudinal fluctuation of intensity. The laser processing with high conical angle Bessel beams is much more resistant to undesirable beam self-focusing and phase self-modulation effects, which enables us to achieve the regime of optimal laser energy deposition for high-quality glass cutting.
Graphene has received much interest from optical communities largely owing to its photon-like linear energy band structure called Dirac cone. While majority of the recent research has dealt with plasmon and polariton of the two-dimensional material, a recently reported graphene light emitter could render a new dimension of applications, particularly in high-speed optical communication. Moreover chemical vapor deposition (CVD) growth technique for graphene is available today providing means for scalable high quality graphene.
The reported graphene emitter provides broadband light emission from visible to mid-infrared which could be instrumental in multi-color display units and optical communications, however a truly large scale implementation has not previously been achieved. Here we demonstrate a CMOS-compatible 262,144 light-emitting pixels array (10 x 10 mm2) based on suspended CVD graphene nano-electro-mechanical systems (GNEMS). A single photoemission area is 19.6 µm2 and a unit pixel is consisting of 512 photoemission devices (16 x 16) where a multiplexer and a digital to analog converter (DAC) are used to control each pixel. This work clearly demonstrates scalability of multi-channel GNEMS light-emitting array, an atomically thin electro-optical module, and further paves a path for its commercial implementation transparent display or high-speed optical communication.
Ultrafast electrically driven light emitter is a critical component in the development of the high bandwidth free-space and on-chip optical communications. Traditional semiconductor based light sources for integration to photonic platform have therefore been heavily studied over the past decades. However, there are still challenges such as absence of monolithic on-chip light sources with high bandwidth density, large-scale integration, low-cost, small foot print, and complementary metal-oxide-semiconductor (CMOS) technology compatibility. Here, we demonstrate the first electrically driven ultrafast graphene light emitter that operate up to 10 GHz bandwidth and broadband range (400 ~ 1600 nm), which are possible due to the strong coupling of charge carriers in graphene and surface optical phonons in hBN allow the ultrafast energy and heat transfer. In addition, incorporation of atomically thin hexagonal boron nitride (hBN) encapsulation layers enable the stable and practical high performance even under the ambient condition. Therefore, electrically driven ultrafast graphene light emitters paves the way towards the realization of ultrahigh bandwidth density photonic integrated circuits and efficient optical communications networks.
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