Prism Pair Research Articles

Ultra-broadband optical parametric amplification based on pre-chirp controlling

For optical parametric amplification with broadband pump coming from the second harmonic of an amplified Ti:sapphire laser syetem, a novel ultra-broad bandwidth phase-matching approach is investigated. The results show that an approximately 400nm phase-matching bandwidth can be obtained by using a 10nm pump bandwidth. Moreover, the phase-matching bandwidth can reach 600nm when the pump bandwidth attains 20nm. In order to obtain temporal overlap of phase-matched spectral components, a linear chirp in the pump requires a quadratic chirp in signal. The photonic crystal fiber with a zero-dispersion wavelength of 800nm generates a supercontinuum with a quadratic chirp. The broadband pump pulse is stretched to a linear chirped pulse by a prism pairs. Calculations concerning the appropriate length of fiber and prism sequence to be inserted in optical path for the pre-chirp controlling were performed, the results of which provide a theoretical basis for implementing the ultra-broadband optical parametric amplification.

Generation of narrowband subpicosecond mid-infrared pulses via difference frequency mixing of chirped near-infrared pulses

The widely used setup for the generation of femtosecond infrared (IR) pulses based on parametric amplifiers (OPAs) and difference frequency mixing (DFM) is extended to produce tunable narrowband mid-IR pulses. The insertion of pairs of silicon prisms after the OPA induces adjustable chirp, which leads to the generation of narrowband pulses in the DFM stage. Rapid tunability of the mid-IR wavelength via a computer-controllable actuator can be achieved in a range of approximately 200 cm(-1) at a bandwidth of the IR-pulses between approximately 15 and approximately 50 cm(-1) and pulse energies up to 0.4 microJ. The narrowband mid-IR pulses are well suited for 2D IR spectroscopy.

Electric Field Enhancement of Nano Gap of Silver Prisms

Using numerical calculation, we examine the effects of gap distance ofa pair of nano gap silver prisms with rounded corners on the locallight intensity enhancement. Two peaks due to localized surface plasmon(LSP) excitation are observed in a wavelength range from 900 nm to300 nm. The results demonstrate that peaks at a longer and a shorterwavelength corresponded to dipole-like and quadrupole-like LSPresonances, respectively. It is found that a gap distance up to 20 nmprovides larger light intensity enhancement than that of a singlesilver nano prism with rounded corners. Furthermore, nano gap silverprisms are fabricated by direct focused ion beam processing, and wemeasure the scattering light spectrum of a pair of nano prisms by aconfocal optical system. However, the two LSP peaks are not observed invisible range because the sizes of the nano gap and prisms are toolarge.

Image inversion and magnification by negative index prisms

A Dove prism and an anamorphic prism pair are investigated in negative index imaging systems. An equilateral triangular prism with refractive index of -1 operates as a negative index Dove prism that inverts as well as images the incident field. A negative index anamorphic prism pair acts as a negative index imaging system with magnification. The relationship between achievable magnification and aberrations is discussed. Both prism systems can be implemented by using negative index photonic crystals, and their performance is demonstrated numerically by the finite-difference time-domain method. These negative index prism structures enhance the functionalities of negative index flat lenses and broaden the applications of negative index materials.

The Comparison Between Experiment and Calculation of the Chirp-Controlled Raman Self-Frequency Shift in a Photonic Crystal Fiber

The control of the spectrum of an ultrabroadband pulse generated by a photonic crystal fiber (PCF) is important for various applications including coherent anti-Stokes Raman scattering spectroscopy. In this study, the spectral peaks due to fundamental soliton pulses near 1000 nm from a PCF have been measured for various input pulse chirps applied by changing the position of one of the prisms in a prism pair. The measured spectra have been compared with calculated spectra and the excellent agreement between the measured and the calculated spectra was observed.

Spectroscopy and Lasing of Yb-Doped <formula formulatype="inline"> <tex>${\hbox {NaY}}{({\hbox {WO}}_{4})}_{2}$</tex> </formula>: Tunable and Femtosecond Mode-Locked Laser Operation

Tetragonal (space group f4 macr) single crystals of NaY(WO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub> ) <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> doped with Yb to a density of 4.52 times 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">20</sup> cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-3</sup> have been employed as laser active materials for the 1-mum spectral range, operating at room temperature. Using Ti:sapphire laser pumping, slope efficiencies as high as 74.6% were achieved without special cooling for the pi-polarization. The Yb-laser was continuously tunable from 1003.7 to 1073.0 nm with a birefringent filter. Pulses as short as 53 fs were obtained at 1035 nm by SESAM passive mode-locking with intracavity dispersion compensation and additional extracavity pulse compression using analogous prism pairs. Experimental data on the spectroscopic properties of Yb <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3+</sup> in the 5-300 K temperature range and the room temperature optical properties of this novel Yb-host is also presented.

Performance evaluation of a wave-front displacement system for vectorial shearing interferometer

We describe a wave-front displacement system using a novel configuration of a pair of wedge prisms. The wave-front propagation, through the displacement system, is analyzed using the exact ray trace. The main advantage, of this configuration, is that the shearing (direction and magnitude) is constant from the displacement system to the image plane. The direction of the shearing depends on the relative orientation of the prisms. The magnitude of the shearing is proportional to the distance between prisms. The proportionality constant depends on the wedge angle and the material of fabrication of the prisms, and it gives the sensitivity to the displacement of the system. The deviation of the shearing due to the difference between the wedge angles is larger than that the produced by the oblique incidence of the wave-front. The experimental results confirm the theoretical data.

Few-optical-cycle pulses in the near-infrared from a noncollinear optical parametric amplifier

We extend the concept of broadband phase matching in a noncollinear optical parametric amplifier (NOPA) to the near-IR. In an 800 nm pumped NOPA using periodically poled stoichiometric lithium tantalate, we amplify a spectrum spanning the 1.1-1.7 microm range and corresponding to two optical cycles of the carrier wavelength. A limited portion of the spectrum is compressed by a prism pair down to 16 fs.

Photonic band gap fibre compressed chirped-pulse oscillator

One of the most successful techniques for generating high-energy femtosecond laser pulses directly out of an oscillator without external amplification is based on intracavity pulse broadening due to a net positive round-trip group-delay dispersion. The main disadvantage of this concept, however, is the need to have an external compressor, often a pair of prisms separated by an optical path length of several metres. In this paper, we demonstrate for the first time an all-fibre compressor based on a photonic band gap fibre. Compared to a standard prism pair the total length of the set-up can be reduced by up to two orders of magnitude while its throughput is increased at the same time.

Propagation of the centroid of arbitrary pulses through angularly dispersive systems

We conduct the experimental investigation of arbitrarily shaped ultrashort pulse propagation through angularly dispersive systems, a pair of gratings, and a pair of prisms, in the linear regime. The propagation time has been explained by the net group delay in the context of centroid of energy arrival as the definition of the pulse propagation time. The temporal positions of the centroid of energy are apparently the same for both transform-limited coherent and arbitrary pulses, despite the fact that the pulses suffer severe distortion owing to strong group-velocity dispersion during propagation through the dispersive systems.

Carrier to envelope and dispersion control in a cavity with prism pairs

Continuously mode-locked lasers combine a broad bandwidth with a fine comb structure that enables high resolution spectroscopy. Independent control of the pulse duration, center of gravity of the spectrum, the mode position, and spacing are essential for spectral applications and metrology. Exact analytical expressions are derived for the first, second, and third order dispersion in a cavity with a pair of intracavity prisms. The influence of cavity controls such as tilt and translation of the end mirror on the frequency comb parameters are analyzed and calculated.

Compensation of resonant atomic dispersion using a pulse shaper

An ultra-short pulse propagating in a resonant dense atomic medium experiences an important distortion due to a strong modification of its spectral phase. This distortion cannot be corrected using the usual simple dispersive devices (a pair of prisms, gratings, etc.). We present here an experimental demonstration of the compensation of this effect using a dual 640-pixel high-resolution pulse-shaper device. A cross-correlation intensity measurement combined with the XFROG (cross-correlated frequency-resolved optical gating) spectral phase measurement of the compensated pulse are performed; efficient correction of the resonant dispersive phase is shown. A spectacular temporal compression of the propagating pulse is then obtained.

Diode-pumped Yb:GSO femtosecond laser

Compact femtosecond laser operation of Yb:Gd(2)SiO(5) (Yb:GSO) crystal was demonstrated under high-brightness diode-end-pumping. A semiconductor saturable absorption mirror was used to start passive mode-locking. Stable mode-locking could be realized near the emission bands around 1031, 1048, and 1088 nm, respectively. The mode-locked Yb:GSO laser could be tuned from one stable mode-locking band to another with adjustable pulse durations in the range 1~100 ps by slightly aligning laser cavity to allow laser oscillations at different central wavelengths. A pair of SF10 prisms was inserted into the laser cavity to compensate for the group velocity dispersion. The mode-locked pulses centered at 1031 nm were compressed to 343 fs under a typical operation situation with a maximum output power of 396 mW.

Bichromatic, phase compensating interferometer based on prism pair compressors

We present a bichromatic prism pair interferometer (BPPI) for controlling the delay between laser pulses of two different frequencies propagating collinearly in a single beam. The BPPI is especially useful when working with ultrafast laser pulses because it intrinsically allows for independent control over the second-order dispersion experienced by the differently colored pulses. We use this control to demonstrate successful precompensation for blue (lambda approximately 390 nm) and UV (lambda approximately 260 nm) pulses that pass through 2.2 cm of dispersive material after the interferometer. The BPPI is extremely flexible and works with all frequencies from the UV to the near-infrared. We demonstrate this by describing measurements made with BPPIs configured for three different combinations of central frequencies.

Compact Single-Stage Femtosecond Multipass Ti:SapphireAmplifier at 1 kHz with High Beam Quality

A compact femtosecond Ti:sapphire amplifier system is reported usingsingle-stage multipass configuration with high beam quality. A highdispersion glass stretcher and a pair of double prisms for compressionare introduced based on broadband femtosecond seed pulses. Thenon-grating-based pulse stretcher and compressor are advantageous toincrease high beam quality and to reduce the high-order dispersion. AGaussian filter is used to reduce the gain narrowing effect inamplification. The compact femtosecond Ti:sapphire nine-pass amplifierdelivers pulses with a duration of 26 fs and an energy of 800 μJat 7 mJ pumping pulses energy at 1 kHz. The 1-kHz femtosecondamplifier with high beam quality and high stability is very suitable forultrafast physics research applications, such as attosecond science,ultra-precision micromachining, and THz wave generation.

Carambola optics for recycling of light

Recycling of light allows the luminance (radiance) emitted by a light source to be increased at the cost of reducing the total luminous flux (radiant power). Recycling of light means returning part of the emitted light to the source, where part of it will escape absorption. An optical design that is suitable for multiple and controlled recycling is described. Carambola optics is named for its resemblance to star fruit. Several pairs of mirrors or prisms redirect light repeatedly onto the source, thus achieving multiple transits of the light through the source. This recycled light exits the carambola in the same phase space as light directly emitted and not recycled.

Femtosecond optical parametric amplification with dispersion precompensation

In this paper, we study a midinfrared femtosecond optical parametric amplifier (OPA) that is severely affected by group velocity dispersion (GVD). Both theoretical and experimental results show that GVDs in nonlinear crystals will significantly degrade the performance of a femtosecond OPA. By introducing a prechirp to the pump pulse, the effect of GVD can be effectively compensated. A lithium-niobate-crystal-based femtosecond OPA demonstrates that the conversion efficiency with optimally prechirped pumping is nearly twice that of the nonchirp case, and the output pulses can be further compressed to nearly their Fourier-transform limit by prism pairs.

Measuring pulse-front tilt in ultrashort pulse laser beams without ambiguity of its sign using single-shot tilted pulse-front autocorrelator

The measurement of pulse-front tilt (PFT) in ultrashort pulse laser beams, without ambiguity of its sign, has been carried out using an in-house built single-shot tilted pulse-front autocorrelator (TPFAC) based on second harmonic generation in non-linear crystal. The experiment is carried out for the beam propagation through a single prism and a pair of prisms. Expressions of PFT angle have been derived to account for beam size, beam propagation effects and for arbitrary incidence of the laser beam. The measured PFT angles were found in accordance with theoretically calculated values. The calculated sensitivity of TPFAC is found to be larger than that offered by the other techniques.

Dispersion‐compensated supercontinuum generation for ultrabroadband multiplex coherent anti‐Stokes Raman scattering spectroscopy

AbstractWe have generated a dispersion‐compensated picosecond ultrabroadband supercontinuum light source at the sample position without using any additional compensator such as a prism pair or a grating pair. The dispersion‐compensated supercontinuum, which is obtained just by optimizing the length of a photonic crystal fiber, has been used as a Stokes laser source for ultrabroadband multiplex coherent anti‐Stokes Raman scattering (CARS) spectroscopy. Owing to an optimized temporal overlap between the narrowband pump and the Stokes supercontinuum pulses, a CARS signal has been obtained efficiently with a spectral coverage of more than 2800 cm−1. Furthermore, a vibrationally resonant CARS signal is observed not only when the pump pulse and the Stokes supercontinuum are temporally overlapped but also when the pump pulse follows the supercontinuum. It can be explained by an impulsive excitation of the vibrational coherence by the supercontinuum and a subsequent probe by a narrowband pump pulse. Using the dispersion‐compensated supercontinuum, we can perform not only the frequency‐domain multiplex CARS but also the time‐domain impulsive CARS measurement by controlling the delay time between the narrowband laser and the supercontinuum. Both these techniques can be applied to microspectroscopy in order to obtain the wide spectral range of vibrational resonances and the suppression of the nonresonant background. Copyright © 2006 John Wiley &amp; Sons, Ltd.

First occurrence of iodine in natural sulfosalts: The case of mutnovskite, Pb2AsS3(I,Cl,Br), a new mineral from the Mutnovsky volcano, Kamchatka Peninsula, Russian Federation

Mutnovskite, ideally Pb2AsS3(I,Cl,Br), is a new mineral from the high-temperature fumaroles of the Mutnovsky volcano, Kamchatka Peninsula, Russian Federation. It occurs as microscopic rubycolored short-prismatic crystals up to 100 μm across, closely associated with halogen-sulfosalts of Pb, Bi, and As, Cd-Pb-Bi sulfosalts, pyrite, anhydrite, and cristobalite. Mutnovskite is transparent in thin fragments with a dark-red to blue color. The crystals are soft and fragile. Cleavage and fracture were not observed and the Mohs hardness is approximately 2. In reflected light mutnovskite is silvery lead-grey in color with an iridescent tarnish. Pleochroism and anisotropy are not visible because of the strong orange internal reflections, especially in immersion. Reflectance percentages measured in air in the range 400.700 nm were tabulated. Reflectance percentages (Rmin and Rmax) for the four COM wavelengths are 34.2, 34.6 (470 nm), 33.2, 33.5 (546 nm), 32.5, 32.7 (589 nm), and 31.4, 31.7 (650 nm), respectively. A mean of four electron microprobe analyses gave Pb 62.0(3), As 11.0(4), Bi 0.6(1), S 14.4(2), Se 0.2(3), I 8.9(3), Cl 2.44(9), Br 1.1(7), Cu 0.03(2), Fe 0.01(1), total 100.7 wt%, corresponding, on the basis of a total of 7 atoms, to Pb1.99(As0.98Bi0.02)Σ1.00(S2.98Se0.02)Σ3.00(I0.47Cl0.46Br0.09)Σ1.02. The nine strongest powder-diffraction lines [d in Å (I/I0) (hkl)] are: 4.69 (32) (002); 4.37 (67) (210); 3.34 (73) (020); 3.19 (100) (212); 2.715 (61) (022); 2.648 (66) (410); 2.539 (31) (213); 2.455 (29) (402); 1.894 (30) (232). Mutnovskite is orthorhombic, space group Pnma, with a = 11.543(1), b = 6.6764(7), and c = 9.359(1) Å, V = 721.3(1) Å3, Z = 4. The crystal structure was solved and refined to R = 4.14%. It consists of three independent cation positions: Pb1 and Pb2 have tricapped trigonal prismatic coordinations with S and I atoms (completed with one As atom in the case of Pb2), while As has threefold coordination with S atoms, which form the base of a trigonal pyramid with As at the apex. Pairs of Pb1-Pb2 prisms are connected in columns which extend along c. AsS3 coordinations are isolated from each other. S atoms and half of the Pb atoms form wavy close-packed layers. Two kinds of channels parallel to boccur between the layers. The smaller channels host As atoms close to the channel walls, with their lone-electron pairs occupying the median part, while the bigger ones accommodate rows of alternating halogen and Pb atoms. The new mineral is named after the type locality, the Mutnovsky volcano, Kamchatka Peninsula, Russian Federation.