The acoustooptic interaction results in the phase modulation of an optical beam by an acoustic wave in a photoelastic medium. An acoustooptic modulator aom, also called a bragg cell or an acoustooptic deflector aod, uses the acoustooptic effect to diffract and shift the frequency of light using sound waves usually at radiofrequency. Included in the discussion are the topics of deflectors, modulators, and. Acoustooptic application note modulator model 3000 series this data sheet is issued to provide outline information only and crystal technology, inc. The material showed one example of having a laser beam shinning on the intensitymodulated acoustooptic modulator which is driven by a rf signal of some frequency e. Mccarron december 7, 2007 1 introduction acoustooptic modulators aoms are useful devices which allow the frequency, intensity and direction of a laser beam to be modulated. Acoustooptic modulation for sound transmission ryersonphysicsvids. Acoustooptic modulators are devices that use sound waves to modify the amplitude, frequency, or phase of light passing through an acoustooptic material. The rf modulation at frequency v causes a traveling density wave to form inside the crystal. Basic acousto optic modulator and driver rf 1st order output 0th order input laser beam intensity modulation sep bragg modulator driver ao modulator key parameters.
A rf signal is fed to a strain transducer in contact with the aom crystal. Acoustooptic, figure of merit, effective elastooptic. The frequency of laser light can be shifted in the rf range through the use of an acousto optic frequency shifter aofs. The characteristics of the diffraction efficiency, compression, cross modulation, and intermodulation intensities are analyzed theoretically. Introduction to acoustooptic modulators by olen rambow september 20 omycroft. Acoustooptic tunable filters are useful for selecting specific wavelengths for excitation light in confocal and multiphoton fluorescence microscopy.
Adjustment of the rf output power is best done with the series 230 driver connected to the acoustooptic modulator. Part i operation of the acoustooptic modulator simple analysis of acoustooptic deflection. Aa optoelectronic offers its customers solutions from prototype design to large volume manufacturing thanks to its internal resources. Connect the rf output bnc jack to an acoustooptic modulator or a 50q, rf load, if it is desired to measure the modulator rf output power. A guide to acoustooptic modulators nickerson devices. How an aom works an aom is a crystal connected to a piezoelectric transducer. Voloshinov, 3 and monish chatterjee 4 1 department of electrical and computer engineering. Applying a radiofrequency electrical drive to the pzt launches a highfrequency traveling sound wave in the medium. These advancements include the analytical treatment of complex interaction geometry, preparation of waveguide materials, design and fabrication of wideband bragg modulators and deflectors bragg cells, and the demonstration of a number of simple. The major advantage of acoustooptic fiber coupled device modulation is the. An aom consists of a piezoelectric transducer pzt bonded to an optical medium glass or crystalline. Within these devices incoming light bragg di racts o acoustic wavefronts which propagate through a crystal.
In our experiment, the acoustooptic interaction length of the aom designed primarily for operation in such a mode was 2 mm. We combine extensive ao device design experience with strict manufacturing. Free space acoustooptic modulators mhz electronics. Pdf this paper presents a new type of acoustooptic modulator based on the conjunction of a piezoelectric contour mode resonator cmr. Also known as bragg cell explanation of acoustooptic modulator. The driver maximum output power is factory preset to the specified level 1 watt. The research in this paper will lay theoretical foundation on manufacture of the fiber acoustooptic intensity modulator. A device utilizing acoustooptic interaction ultrasonically to vary the amplitude or the phase of a light beam.
We present to the reader the mathematical formalism used to describe this phenomena as well as the common. An optional integrated frequencydoubling module that provides conversion efficiencies up to 40% further extends the capabilities of the pulse switch. Modulation and switching of light in dielectric waveguides, in integrated optics, 2nd edn. An introduction to acoustooptics scott e pollack physics 7810 fundamentals of optics and lasers university of colorado, boulder december, 2002 abstract this paper is a brief introduction to acoustooptic phenomena. For proper modulator operation, the optical beam and sound. On the other hand, there are fiber coupled modulators, often realized as a waveguide modulator with fiber pigtails, which can easily be integrated into fiberoptic systems.
Acoustooptic devices a schematic drawing of an acoustooptic modulator is shown in fig. This acts like a phase grating, traveling through the crystal at the acoustic velocity of the material and with an acoustic wavelength dependent on the frequency of the rf. The increased bandwidth allows for chirp control in highspeed data communication. Dynamic optical tweezers using acoustooptic modulators. It is shown that the aom design can be considerably simplified and its size can be minimized if the ramannath diffraction mode is the dominant diffraction mode of aom. Fiber coupled aom is designed for pulsed fiber laseramplifier system applications. They are used in lasers for qswitching, telecommunications for signal modulation, and in spectroscopy for frequency control. Theory and modulator of multipledimensional acoustooptic. In an acoustooptic modulator aom a laser beam is caused to interact with a. Free space acoustooptic modulators the brimrose free space acoustooptic modulator aom with rf driver is used to vary and control laser beam intensity. Low insertion loss compact package stable and reliable performance. This phenomenon, known as the acoustooptic ao dif fraction, has led to a. Focusing for a o modulator analog modulation the acousto optic modulator has a nonlinear transfer function. For materials with a fixed acoustic velocity, the acoustic wavelength is a function of the frequency of the drive signal.
Amplitude modulators basically consist of an electrooptic modulator followed by a polarizer. An acousto optic modulator aom can be used to slowly or rapidly modulate the intensity of a laser beam for example, a variation of this component is specifically designed for use as a qswitch inside a laser cavity. Acoustooptic tunable filters florida state university. Acoustooptic modulators selection guide engineering360. For simple gray level control, the best approach is to characterize the. The model h500 series multichannel acoustooptic modulators allow eight independent beams to be modulated at data rates in excess of 20 mbs. Pdf integrated piezoelectrically driven acoustooptic modulator. A practical problem that arises when using acoustooptic modulators aoms to scan the laser. Pdf acoustooptic infiber modulator using acoustic focusing. By carefully orientating the laser with respect to the sound waves the beam can be made to reflect off the acoustic wavefronts bragg diffraction.
An interesting design is to combine the preceding techniques of tangential phase. A is a world leader in the manufacturing of quality acoustooptic and radio frequency devices. An acoustooptic modulator aom is a device which can be used for controlling the power of a laser beam with an electrical drive signal. Rp photonics encyclopedia optical modulators, acousto. Today i read an introduction on an optical device called an acoustooptic modulator, which is used in many optical experiments. In an acoustooptic modulator aom a laser beam is caused to interact with a high frequency ultrasonic sound wave inside an optically polished block of crystal or glass the interaction medium. Npls technique, which is called rapid acoustooptic scanning raos, uses the acoustooptic effect, which describes how light bends as it passes through an acoustic field. Shaper board for eom driving, combining a laser diode driver. Bulkwave acoustooptic bragg diffraction, in guided wave.
Acoustooptic modulator driven by surface acoustic waves. Acoustooptic modulation for sound transmission youtube. The ability of the acousto optic modulator to shift the frequency of a laser light beam by a precise and stable amount is crucial to production of a beat note from two light beams in this experiment. Rp photonics encyclopedia acoustooptic modulators, aom.
Light from a coherent optical source is focused to a beam waist within the optical medium composed of. In order to properly describe this interaction the acoustic and optical waves will be represented separately, and then the coupling between them will be introduced. This is one of the most useful properties of the acoustooptic modulator. It is electronically programmable using a microprocessor connected to the brimrose rf driver unit. The rf driver features all the necessary components to drive the modulator with analog or. The aom is installed in fiber laser cavity, laser pulses can be obtained by modulating the aom with ttl signal. This angle is in the plane of deflection and relative to a normal from the input optical surface. Ahmad et al calculation of acoustooptic figure of merit for some of oxide crystals cartesian system of 1, 2 and 3, is angle from 1 axis on the 1 2 plane and the angle theta from 3 axis 11. Chapter 12 handbook of optics photonics research group. Comsol mode shape of the compound radial expansion mode of the ring resonator at 1. Bragg 1st 0th rf sep vel input opp1 acoustooptic bragg cell 1106 all specifications subject to change without notice quality assured. Applications and commercial products electrooptic modulator phase modulator is a high performance, low drive voltage external optical modulator designed for customers developing next generation transmission systems. A acoustooptic modulator has a nonlinear transfer function, and as a result, care must be exercised when applying an analog modulation signal to a acoustooptic modulator.
693 891 336 389 881 781 76 342 293 511 859 503 783 1108 316 493 1258 1587 1480 1170 65 1336 603 297 197 1357 588 1526 162 1213 1561 1246 1443 1065 1446 826 800 941 82 1254 1431 525 34 1044 310 1044