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Webb C.E., Jones J. D.C. (eds.) Handbook of Laser Technology and Applications. Vol.1.. Principles (IoP, 2004)(K)(600dpi)(T)(325s)(ISBN 0750309601)_EO_.djvu |
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Size 8.6Mb Date Nov 26, 2005 |
with the surface opposite the 60° coated with a broadband high-reflecting coating...
If the cylinder lens is placed before the
collimating lens, the cylinder radius R is given (approximately) by:
<P2
R = (A3.29)
8nD(\~ cos u)
where cp is the clear aperture of the lens, n is the refractive index of the lens and u is the smaller of the half
acceptance angle of the collimator or the divergence of the laser [8]...
A3.6.1 Q- switching
In a lasing system, the output power is proportional to the population inversion between the upper and lower
energy levels of the lasing transition...
The acousto-optic shutter creates an rf-induced Bragg grating which deflects light out of
the cavity...
Finally, the M2 meter automatically measures beam diameter at
multiple points on a focused beam and compares the observed beam waist and far-field divergence with that
of a theoretical Gaussian, providing important information about how the beam propagates through an optical
system (see section A2.1.4.3)...
Such patterns can cause difficulties in interferometric and holographic
applications where they form a highly detailed, contrasting and confusing background which interferes with
desired information...
In this chapter, we are concerned primarily with the second
possibility, which constitutes the traditional field of nonlinear optics...
By way of illustration, second-harmonic generation
is described using these conventions by the susceptibility x( ^Bw, co,a>), sum-frequency generation by the
susceptibility X/J(<^1 + ^2,^1,^2) and difference-frequency generation by the susceptibility Xjjk^i —
<jl>2,<jO[, —002)...
In contrast, processes such as the intensity-dependent refractive index can occur even as the consequence of
sluggish mechanisms, because in this case the average intensity of the incident light field can lead to a change
of the refractive index...
Note that amplification of the lower frequency input field 0J accompanies the creation of the difference frequency field
The other approach to the generation of radiation at the third-harmonic frequency is to first generate
a field at frequency loo through the process of second-harmonic generation followed by sum-frequency
generation of the fields at frequencies 00 and loo to produce an output at frequency 3a>...
The end mirrors are assumed to be identical and to have reflectivities R\ and R2 at frequencies co\ and 0x2
respectively...
The name
Self-focusing of light 171
phase conjugation derives from the fact that certain nonlinear optical processes have the ability to transform
a field of the form
E(r, t) = A(r)elkz~[a)t + c.c. (A4.25)
into the form
£pc(r, t) = A*(r)e~[kz-[a)t + c.c. (A4.26)
In addition to propagating in a direction opposite to that of the incident field, the wavefront of the phase-
conjugate wave is changed from A to A*...
By a spatial soliton, one means a beam of light that propagates with a constant transverse
profile because of a balance between diffraction and self-focusing effects...
We can see from equation (A4.32)
that, in fact, fa and y must have opposite signs in order for group velocity dispersion to compensate for
self-phase modulation...
From this perspective, spontaneous light scattering occurs as a consequence of fluctuations induced
by thermal or by quantum mechanical zero-point fluctuations and stimulated light scattering occurs as a
consequence of fluctuations that are induced by the presence of the laser field...
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