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Nonlinear effects in cavities and microresonators attract nowadays considerable attention, mainly because they allow generation of equidistant optical frequency combs [1] that are desirable for a number of applications in diverse areas of science. In proper regime, phases of different comb lines may be synchronized leading to formation of stationary soliton states moving along the microresonator....
Quantum-optical states, such as single-photons or quadrature-squeezed light, used for processing quantum-information easily reach optical bandwidths, however homodyne-detection — a major quantum-information tool, is sub-GHz limited. Using optical parametric-amplification we demonstrate effectively bandwidth unlimited optical-homodyne measurement.
Passive optical resonators are important tools for enhancing the sensitivity of spectroscopic measurements [1], and for enhancing the peak and average power of femtosecond laser pulses to the levels necessary for high-order harmonic generation (HHG), e.g. for the generation of XUV frequency combs [2]. The optical bandwidth and thus the pulse duration in such enhancement cavities (ECs) is typically...
It is significant to improve the bandwidth of supercontinuum (SC) and the spectral flatness by more than one wavelength pumping. The broadband spectrum generation by induced phase modulation (IPM) in optical fiber was investigated by Yamashita et al. [1]. Schreiber et al. investigated the SC generation in PCFs by femtosecond single and dual wavelength pumping [2]. In this work, we investigate the...
Astronomical spectrographs combining high resolution (R >> 10, 000) with high stability provide unique scientific capabilities, e.g. for observing the small Doppler shifts which are signatures of Earth-like exoplanets or sensitively measuring isotopic ratios in ancient stars to reveal details of the early universe. Laser frequency combs with mode spacings from 12.5–50 GHz [1] have been shown...
Fully-stabilized optical frequency combs from modelocked lasers are a key component in various applications like optical frequency metrology, optical clocks or ultra-stable microwave generation. The traditional approach to stabilize the carrier-envelope offset (CEO) frequency /ceo in a diode-pumped modelocked laser is via a modulation of the pump current, i.e., by modulating the gain of the modelocked...
Optical frequency combs (OFCs) have led to an impressive number of achievements, including multi-heterodyne spectroscopy [1]. Mode-locked OFCs have been widely used due to their exceptional spectral bandwidth, but they usually require sophisticated locking methods to control the free spectral range (FSR) and the absolute frequency of the comb. A promising alternative is provided by electro-optic OFCs,...
Most few-cycle pulses are formed by compression of an ultrabroadband light source obtained in meter-long hollow-core fiber filled with noble gas [1]. However, the hollow-core fiber scheme requires a careful alignment and is extremely sensitive to the beam-pointing direction, limiting its long-term stability. Recently we reported a novel approach of using a set of plates for continuum generation (MPC,...
Silicon nitride microresonators provide a potentially CMOS-compatible platform for optical frequency comb generation [1]. As in any high-Q microcavity, thermal effects strongly affect the dynamics. This is particularly true considering that typical continuous wave pump powers for microresonator comb generation operate in the 20–35 dBm range. Temporal bright solitons for instance are generated when...
In recent years, Yb3+ doped calcium fluoride (Yb:CaF2) has attracted great attention as a gain media for ultrashort pulse laser oscillator and amplifier. Yb:CaF2 has many advantages suitable for mode locked laser e.g. very broad and smooth fluorescence spectrum shape, relatively high thermal conductivity, and long fluorescence lifetime [1]. Especially, its fluorescence spectrum bandwidth of about...
High repetition rate femtosecond lasers able to deliver pulse energies ranging from few hundred microjoules to the millijoule level is a very active and competitive field in laser research. In laser bulk technology, major improvements toward high average power were (i) the reduction of the pump heat load through Yb-doped crystals development and (ii) the availability of low cost and bright diode-laser...
Low-power, ultrafast, all-optical switches have been developed by tuning the phase difference between transverse modes of a probe beam via intermodal cross-phase modulation (XPM) with a second beam as the control beam [1]. Switching energies in the nanojoule-regime were achieved in few-mode fibers [2].
We report on metrological-grade saturated absorption spectroscopy of CHF3 at 8.63 μm based on CW distributed-feedback QCL laser and a mid-IR self-frequency referenced optical comb. The experimental setup for the saturation spectroscopy of CHF3 is shown in Fig. 1. A CW DFB-QCL with a maximum output power of ∼40 mW tunable in the wavelength range from 8.55 to 8.65 μm, in coincidence with the us (asymmetric...
Lasers with high optical frequency stability have played a significant role in numerous applications including metrology and spectroscopy. A laser with better frequency stability allows shorter integration time and higher accuracy. To achieve this, one of the most crucial factors is the stability of the cavity length of the laser. The length of the cavity is always disturbed by environmental noises...
Hybrid quantum technologies seek to combine the advantages of two individual quantum architectures by transferring the information between the two systems. We want to benefit from the high mobility and ease of transmission of photons for quantum communication and exploit the excellent readout and storage capabilities of atomic qubits as a quantum memory, which is essential to build up quantum repeater...
Photonic Crystal Slabs (PCSs) are nanostructured, dielectric waveguides that feature resonances with small bandwidths and very high reflectivity in the visible spectrum. As refractive index-sensitive transducers, PCSs have been studied for biosensing applications in the past decades [1]. Incident light can couple to and from quasi-guided modes at resonance wavelengths. Due to the evanescent field...
We report our advances in development of subwavelength engineered metamaterial structures in silicon waveguides, specifically high-efficiency fiber-chip couplers, ultra-broadband surface grating couplers and nanophotonic beam splitters, evanescent field waveguide sensors and on-chip Fourier-transform spectrometers.
Terahertz (THz) quantum-cascade lasers (QCLs) constitute a very promising candidate for compact, wide bandwidth, integrated frequency combs [1, 4-7]. QCLs based on heterogeneous cores display the widest spectral coverage reaching more than one octave [2]. The possibility to engineer the gain profile turns out to be fundamental also with respect to dispersion compensation in order to extended the comb...
Passively mode-locked, ultrafast and compact laser sources operating in the wavelength range beyond 2 μm have gained interest for several applications such as nonlinear frequency conversion into the mid-infrared and THz region, material processing, medicine etc. Typically, Ho-doped optical fibers (HDF) are used to directly address this spectral region in ultrafast mode-locked oscillators while Ho:YLF...
Nonlinear wavelength up-conversion from the infrared (IR) to the visible spectrum appears as an interesting alternative for imaging applications. Since early demonstrations [1], work is being done to improve significantly features of up-converted images in terms of the efficiency by intra-cavity continuous wave up-conversion [2] and resolution and field-of-view by incoherent illumination [3]. Direct...
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