Phillip R. Peterson

Diffractive imaging in three‐wave interactions

The coupled signal and idler diffractive differential equations are solved for the parametric processes of upconversion and down conversion. The complex transfer functions are found in terms of spatial frequency, propagation vectors, gain, and media length. Also, we derive the signal to the idler imaging equation by employing the transfer functions for both upconversion and down conversion.

ASE in thin disk lasers: theory and experiment

We derive equations for the ASE intensity, decay time, and heat load. The crux of our development is frequency integration over the gain lineshape followed by a spatial integration over the emitters. These integrations result in a gain length that is determined from experiment. We measure the gain as a function of incident pump power for a multi-pass pumped Yb:YAG disk doped at 9.8 at.% with an anti-ASE cap. The incident pump powers are up to 3kW. Our fit to the measured gain is within 10% of the measured gain up to pump powers where the gain starts to flatten out and roll over. In this comparison we extract the gain length that turns out to be 43% of the pump spot size of 7mm.

Diffractive Raman scattering in focused geometry

The coupled pump and Stokes differential equations are solved by using a rotationally symmetric Gauss–Laguerre decomposition. Three examples of the Stokes and pump intensity are presented.

Power losses in lamellar gratings

Power losses in lamellar gratings per groove length are obtained by integrating the square of the tangential component of the magnetic field, obtained from the infinite conductivity solutions, along the grating profile. The groove fields for the perfectly conducting grating are generated by matching a superposition of diffracted plane waves above the grating to an exact solution of the groove boundary value problem for each polarization. Diffraction effects in the groove energy density and in the power losses are clearly evident.

Power losses in lamellar gratings subject to mixed boundary conditions.

The diffracted powers as well as power losses in the groove bottom, walls, and top are calculated for finite conducting lamellar gratings. The fields are determined from Helmholtz’s equation subject to boundary conditions where the fields and their derivatives are mixed; these conditions are a result of the assumption of a highly conductive grating. A specific example is included for a thin gold-coated grating.

Cryogenic ceramic 277 watt Yb:YAG thin-disk laser

A ceramic ytterbium:yttrium aluminum garnet (Yb:YAG) thin-disk laser is investigated at 15°C (288 K) and also at 80 K, where it behaves as a four-level laser. We introduce a new two-phase spray cooling method to cool the Yb:YAG. One system relies on R134a refrigerant while the other uses liquid nitrogen (LN 2 ). The use of two systems allows the same disk to be tested at the two temperatures. When the Yb:YAG is cooled from room to cryogenic temperatures, the lasing threshold drops from 155 W to near 10 W, while the slope efficiency increases from 54% to a 63%. A 277 W laser with 520 W of pump is demonstrated. We also model the thermal and structural properties at these two temperatures and estimate the beam quality.

Time-dependent thermal blooming in axial pipe flow

The temperature and optical path differences are found for the time-dependent conduction equation with axial convection for an arbitrary heat source. The solution satisfies Dirichlet boundary conditions in the radial and axial directions.

Generalized phase-matching condition for nondegenerate four-wave mixing

The coupled-probe, conjugate, and pump differential equations are solved in the undepleted pump approximation when the pumps are of unequal frequencies. In the usual analysis the two pump wave vectors satisfy k1 + k2 = 0, so that the conjugate and probe wave vectors satisfy kp + kc = 0. The vector phase matching then consists of two one-dimensional problems. However, the unequal pump frequencies require a true two-dimensional analysis, since the pump wave vectors do not sum to zero separately from the probe/conjugate fields. This then requires the inclusion of a transverse dimension in the differential equations. The net result is that the direction of the maximum conjugate intensity, usually determined by the phase-match condition Δk = 0, is instead determined by the generalized condition kc · Δk = 0, where Δk = k1 + k2 − kp − kc. This new phase-matching condition is quadratic in kc, leading to two peaks in the conjugate reflection coefficient.

Recent studies of CW stimulated Brillouin scattering (SBS) in single mode and multimode optical fibers

We report studies of SBS in optical fibers with the goal of using SBS phase conjugation as a passive beam combiner to build high power (>100 W cw) all fiber laser sources. We propose the development of a near infrared high power fiber laser by phasing two Er doped amplifiers in parallel using stimulated Brillouin scattering in a multimode fiber. We use a 1.5 p.m master oscillator-power amplifier configuration (MOPA) to generate SBS in a multimode fiber. The fiber amplifier consists of two Er doped multimode fiber amplifiers (diode pumped), in parallel, which will combine to generate SBS in the multimode fiber.

Circulating pump and single pass pump cw extraction in solid-state lasers

paper deals with the possibility of increasing the energy output with increasing the operational volume of the active medium. The optical scheme of the experiment is given in Fig. 1. The radiation of the master oscillator (A = 1.06 mcm; W = 120 mJ, T = 50 ns, d = 3 mm) with horizonta.1 polarization passed through the Faraday cell 1, 2, 3, was amplified 1-10 times by amplifier A, was expanded by a six-foldl telescope 4, 5 and after the polarization decoupler 6 with aperture 1.7 X 1.7 cm2 entered the FWMF oscillator. The distri-. bution of the intensity of input signal E, in the cell plane differed essentially from the Gaussian one due to the diffraction at the edges of Glan prism 6. The intensity values at the edges of the beam exceeded the intensity in the centre by 20-70%. The FWMF oscillator had the scheme with a linear resonator. The signal radiation with the horizontal polarization passed through cell 7 with an absorbing liquid (acetone solution of Cu(NO,),), then was attenuated by interference polarizers 8, passed through the amplifier, and was returned to the cell through the amplifier and polarizers by mirror 9. The resonator length was 60 cm. The attenuation coefficient of the radiation with the horizontal polarization could vary from 1 to 50 depending on the rotation angle of the polarizers. As a result of interference between the input wave E, and wave E, returned after passing round the resonator, which occurred in the cell, a shortwave grating of the dielectric permittivinput beam diameter 4 mm. F The present