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We demonstrate a single-comb Fourier transform spectrometer by sweeping the pulse repetition frequency of an electro-optic frequency comb. Such combs are more flexible than mode-locked lasers in terms of tunability of the comb repetition rate, which provides an advantage for comb based spectroscopy.
Real-time image data processing tools are proposed to enhance the spectrophotometric absorbance accuracy, using a three-wavelength LED source. The measurements of the beam spot-size allow us to determine the ray displacement in the liquid cuvette and then the corresponding refractive index.
We present a high-resolution optical frequency domain reflectometry for characterization of group refractive index of waveguides in photonic integrated circuits. The method provides a relative accuracy of 10−4 for group refractive index measurements and of 10−3 for its dispersion.
A compact grating with relaxed alignment tolerance for coupling between a fiber and a silicon nitride waveguide is presented. The measured peak coupling efficiency is 22% and the 3dB bandwidth is 58 nm. The fabrication of gratings does not require any etching of materials.
We present a high-speed InP-based photodiode with multiple InGaAs/GaAsSb type-II quantum wells for 2 μm detection. The fabricated photodiode exhibits dark current as low as 100nA at −2V, with an external responsivity of 0.27 A/W, and 3 dB bandwidth of 3.5 GHz at 2 μm.
We discuss the advances of several optical interconnect options, including the VCSEL based, the Si-photonics based, and the monolithically integrated approaches. In addition, we discuss the possibility of using optical method to power and connect smartdust type of devices.
The short-reach optical interconnects used in datacenters and high-performance computing systems are dominated by vertical-cavity surface-emitting laser (VCSEL) and multimode fiber (MMF) links1. The VCSEL-MMF technology is the most cost and power efficient and offers the smallest footprint. VCSELs for 25–28 Gbit/s OOK lanes are in production2 while 25–28 Gbaud PAM-4 with forward-error-correction (FEC)...
A broadband silicon PSR is presented with an insertion loss lower than ∼0.7dB/0.3dB and crosstalk lower than 12.1dB/14.7dB for TE and TM mode respectively. By combining the PSR with AWG and Germanium PDs, an integrated polarization insensitive DWDM receiver is further demonstrated.
Construction of high power nanosecond and picosecond lasers is getting important in many fields of industry and science. Hilase centre combined several hi-tech approaches in laser technology like diode pumping, disk and slab laser concept, ceramic gain media, or cryogenic cooling, and constructed nanosecond and picosecond laser platforms with unprecedented average output power and pulse energy exceeding...
Microresonators have undergone an impressive development in the last decade, opening new pathways to nonlinear optics, laser stabilization, spectroscopy and sensing. Here we present our recent results on linewidth narrowing of quantum cascade lasers and chemical sensing using crystalline solid and liquid whispering-gallery-mode resonators.
An LED light suitable for general illumination is proposed to enhance subconscious visual responses, which are essential to our well-being. Using the silent substitution technique, a melanopsin-selective flicker was added into white light. A linear optimization algorithm suppresses perceivable fluctuations of colors of illuminated objects.
We present our recent works on Microbottle Resonator (MBR) lasers. Wavelength selective and single mode lasing from Ytterbium-doped MBRs and nonlinear processes such as Raman amplification in such resonators are studied.
Octave-spanning supercontinuum is generated in chalcogenide, Ge23Sb7S70, waveguides pumped at 1550 nm. The 2μm side is subsequently amplified in a Thulium-doped fiber amplifier and utilized for second-harmonic generation (SHG). The generated signal has 55 dB of signal-to-noise ratio.
We demonstrate SNAP microresonators fabricated in silica capillary fiber with ultrathin walls by local annealing with a focused CO2 laser and internal etching with hydrofluoric acid. We investigate the introduced capillary wall nonuniformity and demonstrate the feasibility of advanced microfluidic sensing with SNAP microresonators.
Using a non-collinear FOPA, a source delivering 1.8 μm, 30 mJ, 13 fs laser pulses is demonstrated. This is the first step towards 100 mJ for ∼10 TW. This laser opens the way for high brightness soft X-ray attosecond pulses.
We present the differences between Input-Output formalism and Lindblad Master Equation approach in transmission spectrum of Coupled high-Q Cavity with Quantum Dot system in weak coupling regime. Full-width-half-maximum (FWHM) and the peak transmission of Dipole Induced Transparency (DIT) are analyzed in detail.
We present a broadband supercontinuum (SC) generation in highly nonlinear fiber (HNLF) with carbon-nanotube (CNT)-based passively mode-locked erbium-doped fiber laser (EDFL). The passively mode-locked EDFL incorporating CNT-based saturable absorber (SA) has achieved a pulse width of 570 fs with a repetition rate of 18.3 MHz.
We investigate t he ex treme nonlinear optical phenomena using mid-infrared pulses: 1) the laser filamentation in ambient air, pumped by a 2 μm kHz source, for atmospheric chemical detections and 2) the high-harmonic generation i n s olids, dr iven by sub-cycle 2.5–9.0 μm pulses, towards petahertz electronics.
A current injection efficiency model is developed to identify and understand the limiting factors of the internal quantum efficiency in the GaN:Eu based red LEDs. Through this model the design and fabrication of high efficiency GaN:Eu devices in the red spectra regime is feasible.
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