Oscar E Sandoval
12/11/2015
ECE 616: Term Paper
Achieving PW Level Powers via Optical Parametric Chirped Pulse Amplification
Optical Parametric Chirped Pulse Amplification (OPCPA) is a technique that allows for efficient
energy extraction from an amplifier, in this case a nonlinear crystal, without spectral or temporal
distortion (1). This amplification process is implemented by combining Chirped Pulse Amplification (CPA)
and Optical Parametric Amplification (OPA). Both of these techniques will be introduced in the following
sections. OPCPA can facilitate ongoing research in the fields of particle acceleration, plasma physics, and
electron transport. But one major application is Nuclear Fusion. Pettawatt (PW) level systems, such as
the Omega Laser at the Laboratory for Laser Energetics at the University of Rochester, are helping
researchers achieve the ultimate goal of harnessing the immense heat generated by nuclear fusion to
drive electric turbines and thus produce a more efficient energy source. Prior to learning more about the
exciting field of large scale PW level OPCPA, the pioneering work performed by Dubietis et al. in 1992 (2)
will be introduced for laying the foundation of the larger scale more complicated setups.
Prior to introducing OPCPA, the two main pulse amplification techniques will be introduced.
Chirped Pulse Amplification (CPA):
Figure 1. The diagram of CPA invented at the LLE. It allows for efficient extraction of energy from
an optical amplifier while preventing temporal and spectral distortion (3).
The chirped pulse amplification technique was developed at LLE in 1985 (3). This allowed for the
generation of high intensity ultrashort pulses. The goal is to amplify ultrashort pulses and avoid the
detrimental non-linearities in an optical amplifier (4). In very short optical pulses, peak intensities can
become very high and this can lead to detrimental nonlinear pulse distortion. Also, high peak intensities
can lead to destruction of the gain medium. By stretching the pulse prior to amplification the pulse
intensity is reduced, thus reducing the amount of non-linear interactions occurring in the optical amplifier.
After the amplification, the pulse is then recompressed back to its original pulse duration, but now
amplified.
Thus, by reducing the peak intensity of the pulse that is going to be amplified two things are assured.
1. The nonlinearities that can occur in the optical amplifier are reduced, and therefore detrimental
pulse effects can be reduced.
2. Self-focusing can be prevented and thus optical damage of the gain medium can be prevented.
Self-focusing is a process resulting from the intensity-dependent refractive index (5). It occurs
when a beam of light, having a non-uniform intensity distribution, propagates through a material with a
positive nonlinear coefficient (n2>0). The material effectively acts as a positive lens, causing the rays of
light to curve toward each other. The intensity at the focal point of the self-focused beam can usually be
sufficiently large to lead to optical damage of the material. Self-focusing can occur if the power of the
pulse is larger than a critical power value given by (5),
𝑃𝑐𝑟𝑖 =
𝜋(0.61)2 𝜆2𝑜
8𝑛𝑜 𝑛2
Optical Parametric Amplification (OPA):
Figure 2. a) Non-degenerate Optical Parametric Amplification (OPA). Generates a depleted pump,
amplified signal, and highly dispersed idler. b) a laboratory view of laser beams in a BBO crystal. (6)
There are two types of Optical Parametric Amplification (OPA), for the treatment of OPCPA, this
will focus on the nondegenerate case. The process of OPA can be viewed in the figure 2 (6). Here a
pump pulse and a signal pulse are directed to a nonlinear crystal. When these two pulses interact, three
waves can be analyzed after the crystal.
1. The signal pulse is amplified. This is the pulse that will be treated in OPCPA.
2. The pump pulse is depleted.
3. An idler pulse is generated at a different frequency..
The non-degenerative OPA means that the process is independent of the signal phase. However,
care should be taken to make sure that phase matching condition is met.
Δ𝑘 = 𝑘𝑃 − (𝑘𝐼 + 𝑘𝑆 ) = 0 → 𝑃ℎ𝑎𝑠𝑒 𝑀𝑎𝑡𝑐ℎ𝑖𝑛𝑔
This is important because the phase matching condition is what determines the bandwidth gain.
In OPA there is no excitation of media to higher-lying energy levels. Instead the amplification occurs
from the second harmonic generation in a non-linear crystal. This also means that there is no energy
storage in the crystal. That is to say that, amplification only occurs for a narrow temporal window during
which the pump and signal pulses overlap (4). Therefore, care should be taken to synchronize the pump
and signal pulse so as to achieve proper amplification. OPAs also offer other advantages over optical
amplifiers (1), such as.

High gain per single pass.

Low thermal effects thanks to the fact that no population inversion is involved.

Great wavelength flexibility.

Reduced amplified spontaneous emission along with high energy and intensity contrast ratio of
the amplified pulses.

High quantum efficiency, which counterbalances the amount of energy carried by the idler wave

High amplified signal beam quality

Scalability to high energies
But they also suffer from some disadvantages. Such as, lack of pump energy accumulation i.e. no
energy storage, amplified parametric fluorescence, limited aperture of nonlinear crystals, requirements
of precise pump and signal synchronization, and losses introduced by idler wave (1).
Now that the two processes for short amplification have been introduced, it is time to combine
the two and present the OPCPA technique.
Optical Parametric Chirped Pulse Amplification (OPCPA):
Figure 3. General setup of an OPCPA system. A seed laser generates the signal pulse and, although it
doesn’t have to be the case, generates the pump pulse. The signal is stretched prior to amplification,
and then compressed after amplification in an OPA. This results in a high intensity pulse. (1)
Optical Parametric Chirped Pulse Amplification (OPCPA) incorporates the same principles of
CPA, but the optical amplifier is replaced by an OPA. Figure 3 shows the general setup of OPCPA
obtained from (1). The seed laser generates the signal pulse and the pump pulse may be generated by
the same laser or it can be generated by another laser. As an example in (7) the pump laser is generated
via second harmonic generation from a Nd:glass laser. This is chosen as the pump because it operates
with the best energy efficiency for spectrally narrow pulses that can be compressed via available large
area gratings. The signal pulse is stretched thus allowing to efficiently extract energy from the amplifier
without it spectrally or temporally distorting the signal pulse (1).
In typical OPCPA systems a pre-amplifier stage and a power amplifier stage are used. Typically
the pre-amplifier is a β-barium borate (BBO) or lithium triborate (LBO) crystal. In the pioneering work (2)
BBO was used as the OPA. BBO is typically used as it possesses a large gain bandwidth (8). Typically
potassium dihydrogen phosphate (KDP) is used as the power amplifier. KDP is used as the power
amplifier because it can be grown in large dimensions without degradation of the optical quality of the
crystal (1).
Shorter crystals enables a wider phase-matching bandwidth and can support almost octave
spanning bandwidths (6,9). Various methods for realizing broad bandwidth gain have been discussed in
literature (7,10). Two particular relevant to OPCPA are:
1. In the case of the pump and signal being nearly collinear the type of crystal and wavelength can
affect the FWHM of the gain bandwidth. The maximum bandwidth is achieved by operating with
small phase mismatch (close to phase matching coniditon).
2. The second case is for the signal and pump beams to be operated in a noncollinear geometr.
Therefore, many OPCPA systems employ a noncollinear geometry, as did Dubieitis et al (2) did in the
pioneering work.
For broad bandwidth signal gain with a narrow bandwidth pump the phase matching condition
𝑑𝒌
𝑑𝒌
must be met for the following vectors (10) 𝒌𝑝 , 𝒌𝑠 + ( 𝑑𝜔𝑠 ) Δ𝜔, 𝒌𝑖 + ( 𝑑𝜔𝑖 ) Δ𝜔 as well as for the
vectors 𝒌𝑝 , 𝒌𝑠 , 𝒌𝑖 . Solving the following equations gives values for the phase matching angle and
noncollinear angle at a given pump and signal wavelength. Ross et al. (10) has provided solutions over a
wide range of parameters for all crystals.
𝒌𝑝 = 𝒌𝑠 + 𝒌𝑖
𝒌𝑝 = 𝒌𝑠 + 𝒏𝑔𝑠
Where 𝒏𝑔 =
𝑐
𝜈𝑔
Δω
Δ
+ 𝒌𝑖 − 𝒏𝑔𝑖
𝑐
𝑐
is the group index.
However, one consequence of the noncollinear geometry is that the idler wave is highly
dispersed. This is caused because the phase matching condition is achieved over a large bandwidth by a
continuous variation of the direction of the idler (10).
As mentioned before, one of the attractive characteristics of OPAs is the fact that they can work
at a large gain bandwidth. Therefore, an interesting feature of them is that for increasing gain, the gain
bandwidth increases for a fixed crystal length, this is in contrast to optical amplifiers, and it decreases
with increasing gain for fixed pump intensity. This allows for the OPCPA bandwidth to be maximized by
maximizing the pump intensity and minimizing the crystal length in accordance with (6,9). Figures in (10)
show that very large gain bandwidths are possible in OPAs at a variety of wavelengths. (The figures are
not reproduced in this work because the figures are not of good quality, and better quality images were
not found, my apologies.)
OPCPAs can be implemented in either the “front-end” or “back-end” architecture. Examples of
front-end OPCPA systems are the Vulcan laser at the Central Laser Facility in the United Kingdom and
the Omega laser system at the Laboratory of Laser Energetics (LLE) at the University of Rochester. These
type of OPCPA systems offer some advantages. For instance, very high gain per single pass, reduced selfaction effects (such as Self Phase Modulation and Self Focusing), and improved pulse contrast (1). An
example for the back-end architecture is the PALS laser.
The PW laser systems introduced in the previous section are designed for experimentation in extremefield science, transport and acceleration of energetic particles, and plasma physics. For instance, the
Vulcan PW laser system, briefly mentioned before has been used in the following applications (11).

The first user experiment on the PW facility conducted by Professor K Krushlenick and
colleagues investigated advanced particle acceleration schemes. The experiment used a focusing
parabola to produce a high intensity interaction in a Helium jet. It produced, what at the time
was, world leading electron acceleration results.

Researchers from AWE used Vulcan to investigate the electron transport in targets by observing
the heating of a buried layer of aluminum beneath varying thickness of plastic.

Ledingham et al. studied laser driven photo transmutation (the changing of one element into
another by radioactive decay, nuclear bombardment, or similar processes) of materials.

Professor O Willi et al. studied electron beam transport through low density foams.
Figure 4. Overview of nuclear fusion to produce a more efficient energy source. (12)
However, there is one application of PW level systems that can have revolutionary impacts. The
development of nuclear fusion, the origin of our sun’s energy (13), as an energy source. The Omega laser
at LLE was developed to study this (13). How are PW laser systems related to this type of research?
It starts with fuel pellets that are made up of two forms of Hydrogen that are abundant in sea water,
Deuterium and Tritium. Then by performing direct-drive inertial confinement fusion (ICF) the fusion
process can be generated. In ICF high-intensity laser beams are focused directly onto a spherical fuel
target. The target is a shell made up of the previously mentioned deuterium and tritium. The first
interaction with a high intense laser beam results in compression of the fuel pellet. The second
interaction, another high intense laser beam sparks the fusion. The fusion process generates immense
heat, which heats water that is flowing in tubes that are surrounding the chamber. This heating of water
produces steam that can then be used to drive electric turbines. As noted in figure 4, 2lb of this fuel can
generate the same amount of energy as 10,000 tons of fossil fuel (12). Therefore making it an attractive
alternate source of energy. However, more research must be performed in order for this to be a viable
source of energy.
It can be seen why PW level systems are of high interest, and now the question is how OPCPA can
facilitate the reaching of PW level powers. Ross et al. (7) gives a simple setup that is predicted to achieve
11PW level powers by taking advantage of OPCPA.
Figure 5. left) The proposed PW level system by Ross et al (citation). This system is predicted to
result in 11PW of peak power. right) The figure shows the output and input pulse widths for the final
compressor stage. (9)
In this proposed system, the second harmonic from a Nd:glass laser is used as the pump. The
laser output energy was taken to be 3kJ. The OPCPA system is a three-stage amplifier consisting of two
pre-amplifiers (LBO) and one power amplifier (KDP). The power amplifier is operated slightly in the noncollinear geometry as to allow the separation of the signal, pump, and idler beams later in the setup.
The signal is a mode-locked Ti:sapphire oscillator, and the signal is stretched via self-phase modulation
in an optical fiber. The pulse duration of the signal pulse is 0.5ns. At the output of the power amplifier
the output energy is predicted to be 400J, which is within the capacity of the largest available
commercial compressor gratings. Assuming that the compressor is a commercial available compressor
gratings. Therefore there is 224J of energy available to focus on an experimental target. This is due to
the assumption of a single-pass compressor that allows for 70% of the energy to pass and then further
20% loss due to spectral clipping on the gratings.
The compressed pulse is estimated to be 21fs. At this pulse duration, along with the 224J of
energy, this produces peak power of 11PW. How can this pulse duration be assumed? The pulse
duration achievable on target is determined by the product of the source bandwidth and the OPCPA
gain bandwidth combined with other effects in the compressor (9). Expecting an oscillator bandwidth of
1000cm-1, because this is achievable with commercial Ti:sapphire lasers. The following figure shows the
calculated output spectrum which Fourier transforms to a pulse duration of 19fs, then following an
example from literature, the gratings are assumed to produce a compressed pulse of 21fs.
Table-Top OPCPA systems:
In this treatment, OPCPA will be broken into two types of systems. The first will be the “table
top” OPCPA. This will not be the main focus of this paper. However, it lays the foundation for the second
type of OPCPA system. The large-scale, petawatt (PW) level OPCPA system. The following section will
deal with this type of OPCPA technique.
The basic structure of the table top OPCPA was introduced in the previous section, however in
this section, the pioneering work that led to the development of the OPCPA technique will be analyzed.
A brief overview of the development of OPCPA will be introduced and the record for the highest peak
power and average power pulses will be analyzed.
In 1992 the OPCPA method was introduced. This was the pioneering work done by Dubietis et al. (2)
involving a stretcher, an OPA stage, and a compressor resulting in energetic 70-fs pulses (6). Figure 6,
obtained from (2), shows the schematic for their OPCPA technique.
Figure 6. The figure shows the schematic for the pioneering OPCPA system. (2)
The following explanation of the setup was adapted from the (2). The master oscillator in this
setup was a passive mode-locked Nd:glass laser with negative feedback, operating at a repetition rate of
1.5Hz. This oscillator generates 8µs pulses. Using electrooptic switches, 200 pulses in 3µs were selected
and this resulted in a pulse duration of 1.7ps with a spectrum of 27cm-1 at a center wavelength of
1055nm. Two ‘light channels’ were obtained by splitting the beam out of the oscillator. One these
beams was used to obtain chirped pulse, which will be called the signal beam. It is this signal that will
undergo the amplification. The second light channel will be used as the pump.
The signal pulse is attenuated and collimated into a single-mode fiber (SMF). Due to the propagation in
the fiber, the pulses are linearly chirped over a bandwidth of 155cm-1 and temporally stretched to 5ps.
At this point, the energy of a single pulse is approximated to be 8 nJ.
The pump pulse is obtained through pulse stretching and amplification. The pulse stretching was
performed so as to obtain the optimal pulse duration. This was done via spectral narrowing. The pulse
stretcher consists of a grating with 1200 lines/mm, a curve mirror, and a window with a variable
aperture. The grating and the mirror spatially disperse the different optical frequencies making up the
pulse of light. A window is inserted in the focal plane of the curve mirror because this is where the
optimum spatial separation occurs. A flat mirror is positioned directly behind the window so as to
employ a double-pass geometry. At the output of the stretcher, the pulses are stretched and nearly
transform limited. The spectrum, and therefore the duration of the pulse can be tuned by varying the
window aperture. In this setup the width of the spectrum can be tuned from 17 to 3.5 cm-1. This
corresponds to a pulse duration from 2.8 to 15ps. By replacing the window with a mask, various pulse
shapes can be obtained. This pulse stretcher setup should sounds familiar, that’s because it is the same
setup introduced in class for pulse shaping.
A single one of these pulses is launched into the Nd:glass regenerative amplifier cavity. The
pulse undergoes approximately 50 round trips before being saturated and being switched out of the
amplifier. The regenerative amplifier increases the pulse energy from 10nJ to 2mJ. The pulse duration at
the regenerative amplifier output can be tuned from 5 to 17ps.
The pulse at the output of the regenerative amplifier is then launched into a double pass amplifier. The
double pass amplifier is a KDP crystal and this increases the pulse energy to 11mJ. The second harmonic
pulse generated in the 2cm of this crystal is 3mJ.
The pump and the signal beam are both sent into the OPA stage. This stage is a BBO crystal of
8mm in length. This crystal possesses a broad parametric amplification bandwidth, approximately up to
400 cm-1, at 1055nm. The OPA operates in a non-collinear geometry. The pump beam was focused to
the OPA by a lens. The signal wave was projected into the OPA stage via a 16x objective. A single pulse
emerging fiber was amplified from 5nJ to 100µJ.
The amplified signal wave was then collimated and directed into the compression stage. The
compression stage consists of a 600 lines/mm reflection grating and pair of flat mirrors. The grating
operates in the Littrow configuration. The optimal compression was obtained with a compressor length
of 170mm. The pulse duration was approximately 70fs, assuming a sech2 shape. The autocorrelation
FWHM was 110fs. This corresponds to a time-bandwidth product of 0.325, indicative of a transform
limited pulse. The following figures show the spectrum of the pulse after amplification, before
compression, and the autocorrelation trace of the compressed pulse.
Figure 7. a) The autocorrelation trace of the compressed pulse. b) The spectrum of the pulse. (2)
Table 1 shows a comparison of the pioneering work by Dubietis et al. and the work producing the
highest peak power (14) and the work producing the highest average power (9).
Pulse Duration
Energy
Repetition Rate
Power
70fs
100µJ
1.5Hz
Ppeak = 1.43GW
Hermann et al. (14)
7.7fs
130mJ
10Hz
Ppeak = 16TW
Rothhardt et al. (9)
5fs
26µJ
1MHz
Pavg = 22W
Pioneering Work
(2)
Table 1. Table of key parameters of the pioneering work performed by Dubietis at al. (2) compared
to the work performed by (14) for highest peak power and (9) for highest average power.
Large Scale PW level OPCPA Systems:
As mentioned in the introduction, one of the goals of large scale PW power systems is to research
what will one day become a vast source of power using the ocean’s ample storehouse of potential
energy (15).
One of these large scale PW power systems researching how to harness this vast amount of
potential energy is the Omega laser housed at the University of Rochester’s Laboratory of Laser
Energetics. It is a football-field-sized structure that was specifically designed to study direct drive ICF,
which was introduced in the introductory section of this work.
The laser provides 60 UV pulses of light originating from a single 1,053nm IR pulse that is replicated
in successive stages of beam splitting and amplification. These six stages of amplification provide pulse
energies of 800J. Prior to reaching the target chamber, this is where the pulses interact with the
material under investigation, the pulses are frequency converted from 1053nm to 351nm by plates of
potassium dihydrogen phosphate (KDP). The Omega laser provides 30kJ of energy.
Figure 8. Schematic for the Omega EP large scale PW level system. (13)
The Omega laser system underwent an upgrade. The Omega EP (extended performance) is an
OPCPA addition to the Omega laser that would allow the system to reach PW peak power levels.
In order to produce the PW level pulses the Omega EP will need to provide pulses having multikilo-joule, picosecond pulses, and ultrahigh intensities. The system will consist of four different beams.
Two of the beams will provide pulse-widths ranging from 1 to 100ps at a center wavelength of 1053nm.
The energy per pulse depends on the pulse width. For pulse widths of 10ps or greater the energy per
pulse is approximately 2.6kJ. For pulse widths between 1 and 10ps, the energy is scales as a function of
the pulse width because of the damage threshold of the optical coatings at the output of the system. At
1ps the system will produce 1PW of peak power.
As can be seen in figure 8, obtained from (13), in order to achieve the PW level powers one of
the technologies needed is OPCPA. In the Omega EP the OPCPA system make up the front-end and
consists of three amplifier stages. Two pre-amplifiers and one power amplifier. The combination of
these OPAs pumped via a single-pump laser operating at 527nm produce amplified pulses with 400mJ
energy, 8nm wide spectrum centered at 1053nm, at a repetition rate of 5Hz.
The Omega EP schematic is given in figure 8, and the following overview is obtained from (13). A
low-energy sub-picosecond pulse is obtained from a MLL and is subsequently stretched via a diffractiongrating. This stretched pulse is the signal. It is amplified via the front-end OPCPA. After this amplification
the pulse in launched into an angularly multiplexed amplifier chain, i.e. 7-disk booster amplifier, via an
injection mirror. After this the pulse is amplified by a booster amplifier and reflected into the main
amplifier cavity.
The light passes through the cavity amplifier twice, after the second pass a Plasma Electrode
Pockel’s Cell (PEPC) rotates the pulse’s polarization to trap it in the cavity. The PEPC operates like other
Pockel’s cells, however they were developed in the LLE. They use a high voltage 18kV short 250ns pulse
to electro-optically induce birefringence in a KDP plate. These PEPCs are different than other Pockel’s
cells in that the electrodes are helium plasmas on each side of the square KDP plate. After the fourth
pass, the PEPC is turned off and this releases the pulse from the cavity. After the cavity the light is
amplified by the booster amplifier and then sent to a tiled-grating-based pulse compressor.
The tiled compressor is made up of many smaller gratings that are aligned so that they act as
one very large monolithic grating.
There are two limitations to the Omega laser system. The first are wavefront aberrations that
arise from the over 300 optical components in the system and the continuous running of the laser
during the day. The second is the damage threshold of the final grating in the compression stage.
To account for the wavefront aberrations in the OPCPA system, a special polishing technique
developed in the lab was used on the final amplification rods. This technique, known as
magnetorheological finishing (MRF), allows for more efficient amplification from these Nd:YLF
amplification rods. In order to account for the wavefront aberrations after the OPCPA system,
deformable mirrors are placed after the main amplifier cavity and after the final diffraction grating in the
compressor. LLE has developed wavefront sensing capabilities and software to control the mirrors in a
closed loop. These deformable mirrors not only allow for compensation of wavefront aberrations, they
also allow the pulse to be focused in order to perform the nuclear fusion experiments.
To prevent damage of the final diffraction grating in the compressor LLE has developed highreflecting multilayer dielectric coating. The gratings are etched into these specially developed coatings.
Also, by increasing the size of the grating the overall radiation that is exposed to the grating is reduced,
and thus the probability of damage is reduced. The making of these gratings is difficult, therefore the
maximum these gratings can be grown to is 1m.
Table 2 gives a brief comparison of the Omega laser system and 2 other large scale PW level
systems.
The Vulcan laser is a high power laser system composed of Nd:glass amplifier chains capable of
delivering up to 2.6kJ of energy in long pulses (ns in duration) and up to 1PW of peak power in short
pulses (500fs) at 1053nm (16). In 2002 the Vulcan laser system underwent an upgrade to achieve
Petawatt peak power levels (11,17). The 3 BBO crystals making up the OPCPA are pumped via a
customized 2J, 1053nm, 10Hz YAG laser. This generates pulses 4.5ns in duration. The preamplifier
amplifies the signal pulse to 20mJ. To obtain the 670J needed for PW peak power levels two additional
amplification stages are needed. The first stage consists of an amplifier chain optimized for bandwidth
using a combination of Nd:Phosphate and Nd:Silicate amplifying media. The second stage consists of
extra disc amplifier comprised of three ex-Nova 208mm amplifiers. This final amplification stage
achieves the 670J for the PW power level. The compression stage consists of 940mm gold-coated
holographic gratings with a density of 1480 lines/mm. Careful alignment of the compression stage
results in a beam size of 600mm. Finally, after characterization of the pulse via second harmonic
autocorrelation results in a pulse 800fs in duration.
The Prague Asterix Laser System (PALS). The proposed enhancements in (18) would allow the
system to generate 130TW and 1.4PW power levels via a chain of optical parametric chirped pulse
amplifiers. BBO crystals were chosen as the preamplifiers because they support broader spectrum at the
pump wavelength of 532nm. LBO crystal was not chosen as it needs higher pumping intensity which
would require more optical components. KDP or DKDP was not chosen because they do not support a
broad amplification bandwidth around the wavelength of the frequency doubled Nd:YAG pump laser.
The signal pulse is amplified from 1nj of energy to 30mJ by the 3 BBO preamplifiers in the front
end of the system. The KDP crystal is chosen as the power amplifier that is pumped by the third
harmonic of the iodine laser with a wavelength of 438nm. Under this pumping, both the BBO and KDP
would support a broad spectrum, however the KDP crystal is chosen due to its commercial availability in
large apertures needed for the ultra-high-power beams.
The first power amplifier (KDP1) amplifies the signal to the 130TW peak power level. This is
done after the pulse is compressed via the compressor stage. The compressor is a metal coated
diffraction grating with a groove density of 1200 grooves/mm. After compression the pulse is 22fs long,
with a pulse energy of 3.1J corresponding to 130TW of peak power. The second power amplifier (KDP2)
amplifies the output of KDP1 to the 1.4PW peak power level after pulse compression. The compression
of the pulse after KDP2 leads to a pulse with duration of 23fs, pulse energy of 34J corresponding to
1.4PW of output peak power.
Pulse Duration
Energy
Repetition Rate
Peak Power
Vulcan (11,17)
500fs
500J
10Hz
1PW
Omega (15)
1ps
1kJ
PALS (18)
1PW
130TW
1.4PW
130TW
1.4PW
22fs
22fs
3.2J
36J
10Hz
130TW
1.4PW
Table 2. Comparison of large scale PW level OPCPA systems. The Vulcan laser system at the Central
Laser Facility in the United Kingdom (11,17). The Prague Asterix Laser System (PALS) in Prague,
Czech Republic (18).
Conclusion:
OPCPA is a technique to amplify a signal efficiently and without temporal or spectral distortion.
The pioneering work developed this technique and was then extended to larger scale PW level systems.
These large scale PW level systems can be applied to research dealing with nuclear fusion, plasma
physics, and particle acceleration. Ongoing research is being performed so as to make nuclear fusion a
viable form of energy in the future.
References:
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parametric amplification." Selected Topics in Quantum Electronics, IEEE Journal of 12.2 (2006):
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