Quick mtf this software is designed for assessment and comparison physics of the software major lens quality components. A laser resonator with flat parallel mirrors a careful analysis of the resonator will be important in understanding the behavior of lasers, particularly their transverse intensity patterns. Analysis of laser modes in high power unstable resonators. He is a trained toolmaker and worked with trumpf laser systems since the mid1990s in the service area. The beam quality, mode area, threshold gain, and operation reliability are compared between the traditional unstable resonator and the one with a graded reflectivity mirror. Numerical study of unstable resonator in thin disk laser. It has a modern, userfriendly interface, so you need no specialized training or programming skills to use all of its functions and too. It measures physics resolution and chromatic aberration. Pdf numerical study of unstable resonator in thin disk laser.
Huygensfresnel diffraction of hermitegaussian modes by a. One again uses the equation one again uses the equation where a is now the radius of the end mirrors, and l is the resonator length. The people at lightmachinery are veterans of the laser and optics world with many years of experience in the areas of optical design, high power lasers, optical fabrication, laser systems, metrology, thin film coatings and custom machinery fabrication. The fresnel number is a useful concept in physical optics. Extending previous research pertinent to the high equivalent fresnel number regime, we have modeled the optimum performance of a. No attempt is made to be exhaustive in the treatment. The laser resonator gases for co 2 lasers usually consist of a mixture of helium, nitrogen and carbon dioxide.
Glad can model almost any type of optical resonator. Computer programs for doing the barrier calculations are commercially. Software simulation of complex resonator and optical system designs offer the. This is for example the case with very high power lasers. A primary conclusion is that for any laser system characterized by a moderate gain per pass and a fresnel number greater than a few times unity the unstable resonator provides the best practical resonator design for obtaining a highquality neardiffractionlimited output laser beam combined with efficient energy extraction from the laser medium. There is a continuing interest in the design and calculation of laser resonators and optical beam propagation.
The fresnel number f, named after the physicist augustinjean fresnel, is a dimensionless. Excess noise in low fresnel number unstable resonators h m. In some case, if the laser medium exhibits a gain coefficient high enough to allow a high level of losses, unstable resonators can even be very useful. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed. A stable resonator is not a necessary condition to make a laser. Toric concave mirror laser resonator with a big fresnel number. Unstable optical resonators for laser applications abstract.
Optical cavities are a major component of lasers, surrounding the gain medium and providing feedback of the laser light. Simulation of timedependent oscillations in a cw hf chemical. Kaleidoscope modes in large aperture porro prism resonators. Fraunhofer diffraction from fresnel diffraction is the fresnel number defined as. Standing waves are created when two waves with the same frequency and amplitude are interfering while moving in opposite directions. Fresnel number as well as magnification factor on the beam quality were also investigated. Aug 16, 2017 we have developed a suite of programs to help teach the course of laser principle.
The gain of a lasing medium can be enhanced by placing it between a pair mirrors to increase the effective lenght and restrict the allowed spatial and spectral modes of operation, greatly improving coherence and reducing pumping power requirements. This is the usual situation in a stable laser resonator. The concept of the fresnel number has also been applied to optical resonators cavities, in particular to laser resonators 1. Conclusion we have shown that it is possible to design laser resonators having a specified output.
Not generally appropriate for pulsed or timevarying solutions unless the timevarying nature is much slower than a resonator roundtrip time. Numerical calculations of excess noise factors in low fresnel number unstable resonators are. Start by directing the laser beam onto the 200 mdiameter. The high fresnel number resonator led to a bad beam quality with m2. Advances in coating technology today make possible the fabrication of precise reflectivity profile such at those required here. Employs multiphysics simulation to optimise laser resonator design. The dbr configuration comprises two fbgs with overlapping bragg resonances and a given grating separation. The concept of the fresnel number has also been applied to optical resonators, in particular to laser resonators 1.
The one round trip of wave in the cavity should be an integral number times 2p, the resonant frequencies is n kc2l, k is an integral number, c is the speed of light in the medium, l is the cavity length. He is therefore well acquainted with the development of the trumpf resonator series and an experienced expert for possible sources of errors optimization potential of co 2 laser resonators and its system engineering. An optical cavity, resonating cavity or optical resonator is an arrangement of mirrors that forms a standing wave cavity resonator for light waves. The vibrational energy is easily transferred from n.
Expired lifetime application number us07071,155 inventor chunsheu lee stanley l. The software rp resonator for advanced laser resonator design. Optical resonators and gaussian beams resonator stability. New developments in laser resonators new developments in laser resonators siegman, anthony e. Longitudinal optical modes in a laser describe standing waves along the optical axis of the laser. Laser parts, service and support the people at lightmachinery are veterans of the laser and optics world with many years of experience in the areas of optical design, high power lasers, optical fabrication, laser systems, metrology, thin film coatings and custom machinery fabrication. Software optics physics optical design analysis laser. It is meant to be tutorial in nature and useful in scope. Comparisons with simple analytical models and experimental results, author rapaport, alexandra and bass, michael and weichman, louis s and brickeen, brian k and green, steven w, abstractnote no abstract prepared.
Plane parallel resonator consists of two plane mirrors set parallel to each other, as shown in the figure below. A simple model to interpret the numerical results is found, which is discussed as well. Rp photonics encyclopedia fresnel number, fraunhofer. A simple geometrical analysis has been developed which describes the lowestorder transverse mode of any large fresnel number optical resonator located in the unstable or highloss region of the resonator mode chart. Grating eliminated nononsense observation of ultrafast laser light e fields simplified device based on shg frogthick shg crystal for 2. L 1 the resonator fresnel number and the resonator magnification determine the diffractive and geometric coupling of the medium to the optical fields. Optical resonator it is easiest to consider the resonator as an enclosed box with highly reflective walls. Mode spectrum of lasers with stable resonators at large. Wavesim fresnel, software that simulates laser beam propagation through physics various optical schemes. Eigenmodes of an asymmetric cylindrical confocal laser resonator with a single. By using an electric discharge it is very easy to excite a nitrogen molecule to its first vibrational energy level, which has almost the same energy as the upper laser level of co 2. Laser resonator design using optical ray tracing software.
Here g is the equivalent gparameter of the resonator, and n f is the effective fresnel number. Laser cavity is made of mirrors at the end of the active medium. The m2 factor of an output laser beam of the new resonator with a fresnel number of 8. I used fresnel to design a onesided negativebranch unstable resonator for a free electron. Herein a hene laser emitting a gaussian beam is shone on a. The fresnel number f, named after the physicist augustinjean fresnel, is a dimensionless number occurring in optics, in particular in scalar diffraction theory for an electromagnetic wave passing through an aperture and hitting a screen, the fresnel number f is defined as where is the characteristic size e. Rp resonator v4 is a powerful software for calculations on optical resonators. Developed software to predict the performance of electromagnetic waves through a grating. For this resonator, this process takes 11 roundtrips therefore, the angle required is approximately reduced by a factor of 11. The first observation is that unstable resonators do not generate repeating petallike patterns, while stable resonators do.
A page magnifier fresnel lens binder clips cardboard with a white side to. New developments in laser resonators, proceedings of spie. Proceedings volume 7579 laser resonators and beam control xii. Appendixaat the end of the lab manual describes how to perform the nonlinear least squares. In the dfb configuration, the laser cavity is created by introducing a. How can we find the number of round trips to image. In such a cavity, a given number of modes could oscillate, and those modes are determined by the boundary conditions for the wavevectors on the faces of the box each mode is associated with a wavevector with and the dimensions of the box. The required complexity or quality of research of student theses may vary by program, and the required minimum study. Rather, emphasis is placed on formulations and derivations which lead to basic understanding and on results which bear practical significance. This program required that i generalize the theory of gaussian beam propagation to the case. Its user interface combines uttermost flexibility with an easy start, making the software suitable for quick calculations in an industrial environment as well as for advanced research. Vice president and chief scientist, advanced optical equipment and systems corporation, 19941997.
The complicated transverse modes of the symmetric confocal resonator can be visualized in personal computers, which is significant to help the students understand the pattern distribution of laser resonator. Laser resonators the resonator is the mirrors plus all other optical components that act to confine the em wave. Osa optimization of coherent lidar performance with. Laser resonators and beam control xii 2010 publications.
Laser beam and resonator calculations on desktop computers. The fresnel core in an unstable resonator is the region about the optical axis whose radius is such that the fresnel number is approximately. Furthermore, the theoretical results are verified by experimental results. Air products range of resonator gases for welding and cutting. For a dispersive oscillator lasing with a tem 00 beam profile at. In particular, it can be used to produce optimized laser resonator designs. In extension to known concepts of wavelengthmultiplexing diode laser arrays, a new external cavity is presented.
Thermal lensing is one of the key problems which designers of laser cavities for solidstate lasers ssl, dpssl etc. The software rp resonator for advanced laser resonator. Resonator modes and mode dynamics for an external cavity. A solarpumped laser spl that converts sunlight directly into a coherent and intense laser beam generally requires a large concentrating lens and precise solar tracking, thereby limiting its. Rather, emphasis is placed on formulations and derivations which lead to basic understanding and on. The laser wavelengths are much shorter than this box can realistically be. The most simple resonator is a parallelepipedic metallic box each face is a metallic mirror. A new type of toric concave mirror laser resonator with a big fresnel number is presented.
The modal behavior of laser beams from stable resonator at large fresnel numbers is studied using the modal coherence model. Eindhoven university of technology bachelor fresnel diffraction. This is analogous to a splittime modeling techniques. Unstable optical resonators for laser applications ieee. According to the user manual for the zemax optical design software, the correct approximation for propagation in the near field follows the angular. Open resonator article about open resonator by the free. Optical cavity and laser modes university of babylon. Glad general laser analysis and design is the leading program in phys. Therefore a resonator with a fresnel number much larger than 1 will.
Shine the beam through a large pagemagnifier fesnel lens to show how the lens bends light to create images. The properties of an unstable resonator are determined by the round trip magnification m and the equivalent fresnel number n of the resonator. Conceptually, it is the number of halfperiod zones in the wavefront amplitude, counted from the center to the edge of the aperture, as seen from the observation point the center of the imaging screen, where a halfperiod zone is defined so that the wavefront phase changes by. Experimental differences between bare and loaded cavities. The first observation is that unstable resonators do not generate. Some numerical results about the mode spectrum are presented. Larger eigenvalue difference between fundamental mode and the next higherorder mode. Simulation of timedependent oscillations in a cw hf. Eigenmodes of a symmetric cylindrical confocal laser resonator and their perturbation by outputcoupling apertures.
The simulation results disclose that with a graded reflectivity mirror more highorder modes participate in mode competition and the localized mode effect of fundamental. Analyzed a design of laser safety glasses for technical and commercial merit. In previous papers, we reported on the extension of the sfur resonator to a ring cavity 5 and the characteristics of the dot mirror when the fresnel number is outside the range originally conceived by. Using a diffractive eigenmode treatment to model the laser output we show that gradedreflectance resonator optics offer significant efficiency benefits over conventional hardedge coupled unstable resonators in the context of coherent detection lidar applications.