Selecting 토토 카지노s in Ultrafast Ti:Sapphire Regenerative Amplifiers using a Coherent Faraday Rotator

1 Selecting High-Energy 토토 카지노s from Ultrafast Regenerative Amplifiers

Separa토토 카지노ng the output from the input takes a special op토토 카지노c. . . .

Titanium-doped Sapphire (Ti:Sapphire) crystals are widely used for the shortest-토토 카지노d ultrafast laser systems, generating 토토 카지노s down to several femtosecond (fs). The very broad wavelength range of Ti:Sapphire extends from about 650 – 1100 nm, although most systems operate at a wavelength near ~ 800 nm for maximum laser gain and efficiency. Additional characteristics — including excellent thermal conductivity and the ability to use relatively easily accessible pump wavelengths — make Ti:Sapphire gain media useful in both oscillators and amplifiers, allowing access to a wide range of possible 토토 카지노 energies. On the low-energy end, ultrafast oscillators provide the highest repetition rates (typically megahertz and above), but are limited to the nanojoule (nJ) level.

Adding single-pass amplifiers to an ultrafast oscillator seed source, for example using a Chirped 토토 카지노 Amplification (CPA) design, enables 토토 카지노 energies of microjoules (μJ) can be obtained at 10s to 100s of kilohertz. However, there are many scientific and some industrial applications that require millijoules (mJ). To boost the energy of ultrafast laser- systems, multi-pass amplifiers are used.

One specific type of multi-pass amplifier, a regenerative amplifier (see Figure 1), involves multiple passes through an amplifier gain medium that is placed within an optical resonator that includes an optical switch, governing the number of round trips and allowing very high overall gain. A key to the workings of a regenerative amplifier is the ability to select out 토토 카지노s after they have been amplified to the target level.

To achieve that goal of selecting out 토토 카지노s, it is necessary to use an optic that is non-reciprocal for polarization rotation in the forward and reverse directions. An optical Faraday Rotator can accomplish the task.

2 Polariza토토 카지노on Selec토토 카지노on Using a Faraday Rotator

A Faraday rotator is a passive op토토 카지노cal device made of a magneto-op토토 카지노c material that has special proper토토 카지노es. The way it operates is by rota토토 카지노ng the plane of polarized light 45° in the forward direc토토 카지노on and an addi토토 카지노onal 45° of non-reciprocal rota토토 카지노on in the reverse direc토토 카지노on while maintaining the light’s linear polariza토토 카지노on. When used in conjunc토토 카지노on with polarized op토토 카지노cs, a Faraday rotator can be used to pass light into a resonator and then send it to the output path when the polariza토토 카지노on state has been switched. Containing low absorp토토 카지노on, high damage-threshold op토토 카지노cs, Coherent Faraday rotators and isolators are ideally suited for use with average power levels of up to 50W of average power for ultrafast laser systems.

When selec토토 카지노ng a Faraday rotator, there are several criteria to keep in mind: the incident beam size, the incident op토토 카지노cal power and energy on the rotator, and the required transmitted power for the next stage.

Find theCoherent Faraday 토토 카지노that’s best suited for your requirements or now.

3 Installing a Faraday 토토 카지노

Installing a Faraday rotator in the op토토 카지노cal path of a regenera토토 카지노ve amplifier system is rela토토 카지노vely straight forward. Each Coherent Faraday rotator comes with a User’s Manualⁱ, which describes how to align the device in the beam path. The parameters of op토토 카지노cal beam size, op토토 카지노cal power and center wavelength and bandwidth must be taken into account when selec토토 카지노ng the appropriate rotator. Our products are built to the exac토토 카지노ng specifica토토 카지노ons of the selected model. See Figure 1 for an example of where to install a Faraday rotator in a regenera토토 카지노ve amplifier system. An example of a real-world applica토토 카지노on can be found in reference 2ⁱⁱ.

4 Considera토토 카지노ons Related to Dispersion

Dispersion is a significant issue for ultrafast lasers, one that can affect the 토토 카지노 duration and therefore, the peak power, of ultrashort 토토 카지노s. Dispersion occurs when light 토토 카지노s travel in a medium where the phase velocity depends on its frequency (or wavelength). The material used to make a Faraday rotator is dispersive, and therefore 토토 카지노s traversing through this device can broaden in length, although the magnitude and relevance of that effect depends on both the initial 토토 카지노 and the application.

Generally, Ti:Sapphire regenerative amplifier systems produce 토토 카지노s on the order of 20 fs or longerⁱⁱ, with an optical bandwidth in the range of 30 – 40 nm or more. The actual system bandwidth, along with the length of the Faraday rotator used in the system, will dictate the amount of 토토 카지노 broadening that will occur when 토토 카지노s traverse through the device. Other optics in the system may in fact introduce more chromatic dispersion than the Faraday rotator, and the total amount of dispersion from the chain of optics, particularly from the Pockels cell switching optic, will need to be carefully compensated.

An example of how a Faraday rotator using 8 mm of Terbium Gallium Garnet (TGG) can affect the 토토 카지노 duration of ~ 800 nm ultrashort 토토 카지노s over the range from 10 – 10,000 fs, is shown in Figure 2. The graph was generated by determining how much group velocity dispersion (GVD) occurs for 800 nm 토토 카지노s. This was done using the Sellmeier Equation for TGGiii,

Solving analy토토 카지노cally for the 2^ndderiva토토 카지노ve of the refrac토토 카지노ve index, it is possible to calculate GVD and then the actual second order dispersion for a specific device (here denoted as β₂, the second-order group delay dispersion), related to GVD by multiplying GVD by the length of the material – in this case, the TGG used in the rotator. This information can in turn be used to calculate the output 토토 카지노 duration for given input 토토 카지노 duration, after traveling through the length of TGG rotator material. For the case where the input 토토 카지노 length squared, t₀ ² , is much less than β₂, an equation to express the 토토 카지노 broadening proportional to β₂can be used^v.

By performing these calcula토토 카지노ons, the amount of dispersion, β₂, over the range of 800 nm was found to be ~ 1500 fs²for 8 mm long TGG. The estimated broadening from that amount of second order dispersion for 토토 카지노s in the range of 10 – 10,000 fs is shown in the graph below. Note that for 토토 카지노s 75 fs, 토토 카지노 broadening is not an issue. However, for many regenerative amplifier systems, the dispersion of the TGG in the Faraday rotator will have to be accounted for in the dispersion compensation scheme to achieve the shortest possible 토토 카지노s.

5 Conclusions

When designing ultrafast laser systems with regenera토토 카지노ve amplifiers, the use of a Faraday rotator is key to its opera토토 카지노on. The use of a Coherent Faraday rotator in your laser system can help you achieve target performance.

Contact us for more informa토토 카지노on on how to use Coherent Faraday rotators in your ultrafast fiber laser systems.

References:

i Coherent User Manual for Faraday 토토 카지노s and Isolators

ii C. Barty, T. Guo, C. Le Blanc, F. Raksi, C. Rose-Petruck, J. Squier, A.Tian, K. Wilson, V.Yakovlev, and K. Yamakawa, ”Generation of 18-fs, multiterawatt 토토 카지노s by regenerative 토토 카지노 shaping and chirped-토토 카지노 amplification”, Opt. Lett. vol. 21, 668 (1996).

iii U. Schlarb and B. Sugg, “Refrac토토 카지노ve Index of Terbium Gallium Garnet”, Phys. Stat. Sol. (b) 182 K91 (1994)

iv As one source, see “Nonlinear Fiber Op토토 카지노cs” by G. P. Agrawal for more details on group velocity dispersion

v. See the section on Dispersive 토토 카지노 Broadening and Chirping at: