We report the design, fabrication and characterization of novel dichroic mirrors embedded in a tightly confining AlGaAs/Al(x)O(y) waveguide. Reflection at the first-harmonic wavelength as high as 93% is achieved, while high transmission is maintained at the second-harmonic wavelength. The measured cavity spectrum is in excellent agreement with finite-difference time-domain simulations. Such a mirror is essential for achieving resonant enhancement of second-harmonic generation.
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http://dx.doi.org/10.1364/ol.31.003285 | DOI Listing |
Nanophotonics
January 2024
School of Physics, Xidian University, Xi'An 710071, P.R. China.
In this paper, we report the use of femtosecond radially polarized vortex laser with MHz repetition rate for direct writing of cladding waveguides (WGs) and realization of waveguide laser oscillations in ytterbium-doped calcium fluoride crystal. The negative refractive index modification in Yb:CaF crystal is fabricated by the homemade all-fiber laser amplifier. At 976 nm pump wavelength, these Yb:CaF WGs can achieve continuous-wave (CW) laser oscillation.
View Article and Find Full Text PDFHeliyon
November 2024
Institute of Semiconductors, Chinese Academy of Sciences, Beijing, 100083, China.
A study is conducted on a GaAs-based high-contrast subwavelength chiral metasurface (HCCM) designed for 1064 nm. The metasurface integrates a high-contrast subwavelength grating (HCG) for TM mode modulation, a SiO support layer, and a compact quarter-waveplate (QWP) to convert linearly polarized light to circularly polarized light. The HCG achieves ultra-high reflectivity at 1064 nm, attributed to the large refractive index contrast between the Si grating and SiO2 layer.
View Article and Find Full Text PDFYtterbium (Yb)-doped materials are an excellent choice for efficient and powerful ultrafast lasers. They exhibit favorable emission properties, which include a low quantum defect and compatibility with cost-effective high-power pump diodes. While being strongly beneficial for efficiency, the low quantum defect is a challenge for operation in the few-cycle regime.
View Article and Find Full Text PDFSmall Methods
November 2024
State Key Laboratory of Extreme Photonics and Instrumentation, International Research Center for Advanced Photonics, Centre for Optical and Electromagnetic Research, College of Optical Science and Engineering, Zhejiang University, Zhejiang, 310058, China.
Near-infrared II (NIR-II, 900-1880 nm) fluorescence confocal microscopy offers high spatial resolution and extensive in vivo imaging capabilities. However, conventional confocal microscopy requires precise pinhole positioning, posing challenges due to the small size of the pinhole and invisible NIR-II fluorescence. To simplify this, a fiber optical wavelength division multiplexer (WDM) replaces dichroic mirrors and traditional pinholes for excitation and fluorescence beams, allowing NIR-IIb (1500-1700 nm) fluorescence and excitation light to be coupled into the same optical fiber.
View Article and Find Full Text PDFAdv Sci (Weinh)
December 2024
Organic Semiconductor Centre, SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews, KY16 9SS, UK.
Organic light-emitting diodes (OLEDs) have been developed for high-speed transmitters of visible-light communication (VLC) but so far the possibility of direct fabrication of multiple colors on a single substrate has not been exploited for multi-Gbps data transmission. Very fast red-, green-, and blue (RGB)-emitting OLEDs are developed on a single substrate to realize high data transmission speed by wavelength division multiplexing (WDM). -6 dB electrical bandwidth of over 100 MHz is achieved for all colors by selecting fluorescent materials with nanosecond emission lifetimes and little overlap between their emission spectra and incorporating them into OLEDs designed for high-speed operation.
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