Laser amplifier

In the previous chapter we have introduced the physical basis of the interpretation of optical spectra of centers in crystals. The main effect of these centers is to introduce new energy levels within the energy gap of the crystal, so that the transitions among these levels produce new optical bands that are not present in the perfect crystal. Due to these absorption and emission bands, centers in crystals are relevant for a variety of applications, such as solid state lasers, amplifiers and phosphors for fluorescent lighting and cathode ray tubes. In this chapter, we will describe the main characteristics of the relevant centers for these applications. 

A. Larsson, N. Eriksson, S. Kristjansson, P. Modh, M. Uemukai, T. Suhara, and H. Nishihara, Grating coupled surface emitters integrated lasers, amplifiers, and beam shaping outcouplers, SPIE 3626, 190-200 (1999). 

The effects of Nj and He on the rotational relaxation rate in the CO2 00° 1 upper laser level have been measured by Abrams and Cheo 379), who used the output of a g-switched CO2 laser (1 Kw peak power, 20 nsec) to selectively deplete the population of one rotational level in a flowing CO2, CO2 + He and CO2 + N2 laser amplifier. The relaxation from neighbouring rotational levels into this depleted state showed up as a recovery of the amplifier gain at the corresponding line which was detected as a function of time with a third cw single-frequency CO2 laser. 

Figure 9. Design of the dye laser amplifier. Ultrafast laser pulses are amplified roughly 10,000 times by seven passes through a dye jet pumped by a copper vapor laser.

Experimental Setups. The experimental configurations used for CARS measurements have common features in most laboratories now. Figure 2 shows one such arrangement which is typical. A pulsed laser, in most cases a Q-switched Nd YAG, is used to generate the (o. frequency at 532 nm. In a few cases experimenters use ruby or other solid state pulsed lasers. Typically the 532 nm beam is split and the second beam is used to pump a dye laser -dye laser amplifier leg. This produces the ou probe frequency. 

Figure 1. Diagram of apparatus for picosecond fluorescence studies using streak camera detection. A laser oscillator B dye cell C output reflector D polarizer E spark gap F KDP pockels cell G polarizer (crossed with D) H clear glass beamsplitter J laser amplifier K pin photodiode L transient digitizer M,N 1054 nm reflectors P 2nd harmonic generator Q 3rd or 4th harmonic generator R spectrograph S streak camera T biplanar photodiode U image...

C. Honninger, R. Paschotta, M. Graf, F. Morier-Genoud, G. Zhang, M. Moser, S. Biswal, J. Nees, A. Braun, G.A. Mourou, I. Johannsen, A. Giesen, W. Seeber, U. Keller, Ultrafast ytterbium-doped bulk lasers and laser amplifiers, Applied Physics B 69, 3 (1999). 

We have undertaken an experiment to try to improve the performance of pulse amplifier experiments. The system is shown schematically in figure 2. It consisted of a continuous-wave C102 dye laser amplified in three stages by a frequency tripled Q-switched NdtYAG laser. The output energy was approximately 2.0 mJ in a 150 MHz linewidth and was up-shifted from the continuous-wave laser by 60 MHz caused by the frequency chirp. This light was then spectrally filtered in a confocal interferometer with a finesse of 40 and a free spectral range of 300 MHz. The linewidth of the filtered radiation was approximately 16 MHz. 

Quantum dots have been widely explored during the last few years for their interesting optical properties and for their possible applications in diode lasers, amplifiers, and detectors. Quantum dot behaviour, observed both in single- and in multi-walled CNTs,17 18 is determined by the unique electronic structure of these particles. Moreover, a CNT can act as a quantum wire capable of... 

The instrument was based on a standard Ti sapphire laser-amplifier system generating 80 fs pulses at 800 nm at a repetition rate of 1 kHz. 

Such single-mode lasers, often pulse amplified by dye laser amplifiers pumped by injection-locked Nd YAG lasers, are used in nonlinear Raman techniques by which an instrumental resolution better than 0.001 cm is achieved (Esherick and Owyoung (1982), Schrotter et al. (1988a)). 

Dves and Related Systems - A major reason for an interest in dyes is the search for continuous improvement in the design of tuntable lasers. Amplified spontaneous emission is observed from... 

Figure 16.16. Ex situ synthesis of optical composite for laser amplifying films. [Adapted, by permission, from Beecroft L L, Ober C K, Chem. Mater., 9, 1997, 1302-17.]...

Fosterite Tribromo styrene/ naphthyl methacrylate 100 optical composite for laser amplifying films 63... 

The apparatus employs a passively mode locked Nd/YAG laser oscillator, a Pockel cell pulse extractor, and Nd/YAG laser amplifier to produce laser pulses at 1064 nm. Non-linear crystals convert 30% of this light to 355 nm, which is used for excitation of the sample. The optical path length of the 355 nm light is varied by a computer-controlled time delay stage. 

The transient absorption setup used in our experiments is a versatile tool providing both the necessary time resolution and the tunability to investigate different compounds. The pump-probe spectrometer is based on two noncollinearly phase matched optical parametric amplifiers (NOPAs) (see Fig. 11.3) [21, 22]. The NOPAs are pumped by a regenerative Ti sapphire laser amplifier delivering approximately 100 fs NIR pulses at around 800 nm with a repetition rate of 1 kHz. 

OSC = Laser Oscillator AMP = Laser Amplifier PCD = Pockels Cell Drive... 

The originally doubled, Nd-YAG (2 x Nd-YAG) laser beam at 532.0 nm is directed through a KG-3 filter to remove any 1.06-um energy. Part of this laser beam is used to excite the dye in the dye-laser amplifier cell. Usually about 30% of the originally doubled ND-YAG beam is used for dye pumping and the residual 70% is directed to the CARS test section. The dye amplifier cell (DC) is at Brewster s angle to maintain the horizontal polarization of the dye-laser beam. 

Black et al. have measured the quantum yield of S( 5) as a function of wavelength as part of the continuing search for suitable laser amplifier systems based on the metastable states of elements in Group 6. In the range 110 ran < X < 170 ran, they found 0[S( 5)] 1.0 between 142 ran and 160 ran, which precisely mirrors the... 

Assume that a product called 10-cm disk aperture laser amplifier is selected for a composite index. Although the 10-cm disk amplifier was produced only during period 0, tracing of selected cost items has continued. To worry about all amplifier components is too involved, so major items were picked for individual tracking, and spot prices have been gathered for 4 years. The quantity of each of the five materials is in proportion to the initial one-time cost of the material to the total cost. Some materials have declined in price, whereas others have increased. Prices for each material have been gathered (or imputed for periods where no information was available) and are shown in Table 2. 

---