# What is Resonator: Definition + 64 Threads

A resonator is a device or system that exhibits resonance or resonant behavior. That is, it naturally oscillates with greater amplitude at some frequencies, called resonant frequencies, than at other frequencies. The oscillations in a resonator can be either electromagnetic or mechanical (including acoustic). Resonators are used to either generate waves of specific frequencies or to select specific frequencies from a signal. Musical instruments use acoustic resonators that produce sound waves of specific tones. Another example is quartz crystals used in electronic devices such as radio transmitters and quartz watches to produce oscillations of very precise frequency.

A cavity resonator is one in which waves exist in a hollow space inside the device. In electronics and radio, microwave cavities consisting of hollow metal boxes are used in microwave transmitters, receivers and test equipment to control frequency, in place of the tuned circuits which are used at lower frequencies. Acoustic cavity resonators, in which sound is produced by air vibrating in a cavity with one opening, are known as Helmholtz resonators.

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1. ### I Microring resonator matrix

Hello everyone, A simple ring resonator with a bus waveguide is described by: $$\begin{pmatrix} E_{t1}\\ E_{t2} \end{pmatrix} = \begin{pmatrix} t & k\\ -k^* & t^* \end{pmatrix} \begin{pmatrix} E_{i1}\\ E_{i2} \end{pmatrix}$$ I do not understand though why we have -k* and t*? Shouldn't...
2. ### I How to calculate the ring resonator radii via Laplace?

Dear forum, I was trying out two different approaches to calculate the dimensions of a ring resonator (sketch below) and got two slightly different solutions. The first approach is to assume that the waveguide wavelength has to fit n times onto the circumference of the ring (taking the average...
3. ### I Interference and conservation of energy in a resonator

It is known that constructive interference in one place must be compensated for by destructive interference in another. Take a simple Fabry Perot resonator for example. The interference occurring at both sides of the first mirror (assuming one incident electric field) compensate each other out...
4. ### A What is a good basis for coupled modes in a resonator?

Suppose, there is an electro-optical modulator that can couple the neighboring modes in an optical ring resonator. The Hamiltonian for the system looks something like this^^ (see the attached image). Here we sum over all modes m and 𝜙0 is a parameter. What will be a good set of basis for the...
5. ### Transmission line resonator

Hello everyone, I am studying transmission line resonators and in particular I was considering a particular case of resonator where I have an open circuited quarter wavelength transformer of high impedance terminating a regular 50 ##\Omega## line. If I look at the input impedance from the open...
6. ### Calculating Resonator Stability with Lens & Mirror

I guess the resonator will be stable when both focal lengths of lens and curved mirror meet. The curved mirror is fixed and it's focal length: $$f_{curved} = \frac{R_{2}}{2} = 50 \, mm.$$ Then the d should be: $$d=f_{lens}+f_{curved} = 100 \, mm.$$ I think that's also the distance for which the...
7. ### Difference between Waveguides and Resonators

I claim that waveguides are resonators because a resonator is defined as a device which can produce you normal modes of some ' mathematical object' you're looking for, which in waveguide's case is Electromagnetic fields ( waveguide can produce normal modes called TE and TM ). Am I right?
8. ### How Does Resonance Frequency Affect MEMS Accelerometer Performance?

Hello, I am designing a resonant mems accelerometer. It has a resonating beam. We are actuating it by AC voltage + DC voltage. We are going to actuate it at beam's resonance frequency. When I search for papers related to previous studies, I encounter resonance frequencies ranging from 20 kHz to...
9. ### I Helmholtz resonator with multiple necks--formula?

Does anybody happen to know the formula for resonant frequency of a Helmholtz resonator having N necks? Physics is not my field and I'm a bit over my head. I need the formula for a computer program related to musical instruments--this is the only thing holding me up. It seems like it would...
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### A Helmholtz Resonator: attenuation vs. amplification

Hello guys, I read the other threads about HR, resonances and so on, but I couldn't find a clear explanation of what the practical implications of using a HR are. From one side, HR is described as a "reactive element", used in several contexts to attenuate a specific noise by means of...
11. ### Longitudinal/transverse modes in optical cavity (resonator)

I am learning about lasers and trying to clear up some blurry concepts in my head so I am not necessary using heavy math for description here so please bear with me. Let's take EM field in a rectangular box with walls that are perfect conductors (optical cavity). EM field distribution inside...
12. ### A How a laser resonator generates the standing wave?

Hi, guys. I'm interrest in the question about how optical (laser) resonator can generates the standing wave? As i know, there is a condition that the resonator base (lenght between two mirrors) should be multiple to the length of the wave. (L=k*(lamda/2)). But in practice no one never measures...
13. ### Fast Q-switching of flash pumped Nd:YLF laser

Hi friends! I solved the problem 8.3 of Problems in Lasers Physics'' book (by Cerullo, Longhi, Nisoli, Stagira and Svelto) but I think there's a mistake on the solution presented in this book in page 196. This is a problem book with problems and solutions that follows closely the laser...
14. ### B How Many Layers of Aluminum Foil Are Needed for a Resonant Cavity?

I want to build a Resonant Cavity to play with frequencies around 100-700 mhz. I'd like to try different shapes, so I was thinking in using a cheap malleable material like aluminum foil. Questions: - I think one layer of aluminum foil might be too thin.. If I paste a couple of layers will do...
15. ### Superconducting Resonator matches 3 Degree Kelvin Spectrum

Carver Mead writes in his book, "Collective Electrodynamics", that experimental evidence indicates a superconducting ring and capacitor resonator circuit will increase from zero voltage (scalar potential difference) to an energy matching a 3 degree Kelvin black body radiation spectrum...
16. ### How does a Resonator enhance coherence? (LASER)

Hello, the resonator of a laser system is said to have 3 functions: Amplification in one direction, selection of one or few frequencies, and enhancement of coherence. I have a question about the coherence part. I see that the stimulated emission process produces phase matched light. Initially...
17. ### Laser that doesn't have a resonator?

Is it possible to have a laser without a resonator? My guess is you can as you would still get some proportion of light coming from the inverted medium. My question is how would this light be different (from that of a laser with a resonator) and are there any practical uses for such a device?
18. ### Series Coupling Capacitor as Impedance Inverter of Resonator

Hi, I have been having this question for a long while. From Pozar's book (Microwave Engineering), on page 336, when he was solving for the resonance response and the Q factor for a Lamba/2 resonator terminated by an open circuit, and coupled to the feed line through a series capacitor, at some...
19. ### Reflection coefficient S11 vs Resonator animation

Hello, I'm trying to do an animation of a photon being absorbed by a resonator vs. the corresponding S11 plot being plotted against frequency. Can anyone give suggestions on how to go about this. As the photon goes through Vin, at other frequencies it will be reflected and probed at Vout. This...
20. ### Hi-Q resonator and photon pair

I am trying to "perform" a thought experiment suggested in http://arxiv.org/ftp/quant-ph/papers/0206/0206190.pdf (Not that I personally have anything against non-locality :angel: Some of my best friends are non-local.) A source generates a single, narrow gated pulse of light containing one...
21. ### Can I Replace a Dielectric Resonator with a Filter?

I want to replace a dielectric resonator in a satellite LNB to change the frequency of the LO. Can I use a filter to replace this resonator? a Helical filter maybe.
22. ### Relationship between size and frequency of an oscillator

I've always just accepted that as you scale down a mechanical system the frequency and Q factor both increase. For example, this Wikipedia page simply says that "Small bells ring at higher frequencies than large bells". But for a driven damped harmonic oscillator, what is the exact relationship...
23. ### Cylindrical cavity resonator problem

Homework Statement Q. A cylindrical cavity resonator has diameter of 24 mm and length 20 mm. The dominant mode and the lowest frequency band are operated as ? I am providing a picture of problem to show the options given to me. I solved the problem by calculating resonant frequency for cavity...
24. ### Waveguides and Cavity resonator Equation confusion

Homework Statement This is not a homework question and I am asking this question out of curiosity. We have been taught rectangular wave guides and cavity resonator recently and I don't want to gulp the wave equations as it is, so the problem that I am facing ( I have written it on paper and...
25. ### Microwave rectangular cavity resonator ?

Homework Statement I am putting the picture of the equation given to me in book , I feel it to be wrong please tell me that is the equation written in book correct or not ! Homework EquationsThe Attempt at a Solution
26. ### Understanding Stability Conditions for Unsymmetric Optical Resonators

I am trying to understand the conditions for an optical resonator with unsymmetric reflectors, i.e. the focal lengths of the two reflectors are different. According to wikipedia (http://en.wikipedia.org/wiki/Optical_cavity#Stability) 0 < (1 - L/R1)(1 - L/R2) < 1 is the equation that will...
27. ### Lower Q of Crystal or Ceramic Resonator

I'm working on a school project that requires me to build a RF oscillator that is able to be started and stopped at about 100kHz. Ceramic or crystal oscillators would be good because of their tiny size, however, the high Q factor creates a problem. So my question was, can placing a resistor in...
28. ### Dielectric resonator - microwaves

Hi, recently there was an article in one scientific journal where they claimed that when microwaves are shined on a mixture of dielectric solid (powdered or crystalline) of high dielectric constant with some liquid, the EM field is much higher, both in the dielectric and in the liquid, as...
29. S

### Does quality factor of a resonator depend on the excitation signal?

Hi I am curious to know if quality factor of a resonator depends on the excitation signal or if it stay the same irrespective of the signal applied? Thanks
30. ### Helmholtz Resonator using voltmeter

Hi, I am trying to understand how precisely a voltmeter is used to measure the resonant frequency of a sound wave in a helmholtz resonator. Is it simply that the maximum voltage corresponds to the resonant frequency? A detailed description or external link would be great. Many thanks.
31. ### How do electrons induce resonance in a cavity resonator?

I've been reading lately in particle accelerators and electrons and it got me wondering. How do electrons induce resonance in a cavity resonator? Do they have to first be accelerated to one of the walls of the cavity where they then bounce off toward the other wall?
32. ### Optical Photonic Devices: Ring Resonator

Hi there, I have been researching an optical Ring Resonator and have been given the following values: FSR=100GHz, Q=10000, Wavelength (λ)=1.55um (micro), ng=3.7 and neff=2.3. Using these values I was asked to calculate the k value (coupling coefficient), length of ring, length of the...
33. ### Will a resonator change its Freq while energy is added?

Consider this, will resonator change its frequency while energy is being added or removed? Why? Should not matter if the resonator is mechanical or electrical.
34. ### How to Design FP resonator from Bragg mirror in Matlab?

Homework Statement Below is a {MATLAB}code for Bragg mirror. How can I implement the code to create an FP resonator? Homework Equations The Attempt at a Solution %User input parameters num_layers = input('The Number of Layers in the structure = '); r_index1 = input('refractive...
35. ### The quality factor of cavity resonator

Hello i have to derive the quality factor Q i must start with Q=2\pi\frac{internal-stored-energy}{energy-loss-per-cycle} the quality factor should be in terms of λ so the last equation shall be Q=\frac{4\pi L}{\lambda (1-R)} i searched in google but i always get the Q-factor in...
36. ### Radio Signal With No Resonator?

I am a beginner at electronics, and wanted to make a simple (non-audio) radio transmitter and reciever, with no inductor-capacitor resonator, since I don't understand it and I am not making an audio radio. Here is my transmitter, with the input wire to the BJT being the signal: Here is my...
37. ### Helmholtz resonator equation. How do I do this? Please help.

Helmholtz resonator equation. How do I do this?? Please help. L = 0 Vo = 473.17 (I think its cubed though I calculated it from 16 ounces, so I should be cubed right??) A = What I am solving for F = 480 hz V= speed of sound which is 340.19 at sea level If Vo needs to be cubed then A...
38. ### How Can I Design an Underdamped RLC Resonator Below 3kHz?

Hi, I thought this would be a simple project but I have not been able to get this to work. I need to design a circuit that exhibits a resonance below 3kHz. It must be underdamped, and the drive current limited to ~5mA. I was usign this as an inductor...
39. ### Gaussian Beam in a Symmetric Confocal Resonator.

λHomework Statement A symmetric confocal resonator with mirror spacing d =16 cm, mirror reflectances 0.995, and n = 1 is used in a laser operating at λ[o] = 1 μm. (a) Find the radii of curvature of the mirrors. (b) Find the waist of the (0,0) (Gaussian) mode. (c) Sketch the intensity...
40. ### Guitar acting as a helmholtz resonator. Explanation?

Homework Statement I have a bit of a problem in class. I am attempting to do an assignment on sound in relation to a guitar. For this I need to explain how the guitar is a highly energetic intrument. I do not know if looking at is like a helmholtz resonator is a waste of my time or not but I'm...
41. ### Resonance frequency of confocal resonator

Homework Statement A symmetrical confocal resonator has a length d=30cm, and the medium has refractive index n=1. Determine the frequency spacing \nuF and the displacement frequency (\Delta\varsigma/\pi)\nuF. Determine all the resonance frequencies that lie within the band 5*1014\pm2*109Hz...
42. ### Is a resonator linewidth affected by its nonlinearity ?

Hello everybody, I am new on this website and I hoppe I choosed the right section. If I am correct, the linewidth of a resonator 2Δf must be defined by the product of its damping rate γ and its resonance frequency f : 2Δf = 2.γ.f In my case, I want to consider a strongly nonlinear...
43. ### How Do Resonance Frequencies Change with Sphere Position and Design?

Lab part I: We had to work with resonators. Huge box! Lowered a solid glass sphere into the box and measured the distance from the lid to the sphere. Varied the distance and measured the resonance frequency at the varies distances. Q: ∆f =f(at distance x) - fr , fr = resonance frequency of the...
44. ### Resonant wavelength of a cavity resonator using different internal materials?

Hello everyone, Recently I have been studying cavity resonators. I noticed that all cavity resonators have air in them, but I was wondering what the effects would be if something other than air was used? For the sake of simplicity let's say we put a dielectric material in it with a...
45. ### Helmholtz resonator? Intake manifold design

Helmholtz resonator? Intake manifold design Hi guys, I'm doing a bit of research into engine intake manifolds. The information I've found so far looks staright forward, but it's given out by turners and cottage industry designers, rather than engineers or physicists, so it's basic. I...
46. ### The Q factor calculation for the two-port SAW resonator

In some papers, I found that the Q of resonator, i.e. one-port SAW resonator, can be calculated with the formula 1/f0*(diff(phi(f),f)@f=f0),phi(f) is the phase of impedance, I have tested one one-port saw resonator with the network analyzer agilent4395A under the impedance mode, then process...
47. ### Electromagnetic waves in a cavity resonator

If EM waves are pumped into a resonant cavity at it's resonant frequency will each incoming wave add it's energy to amplify the wave(s) in the cavity? I know that if you pulse a light source into a circular wave guide and you pulse the light source each time the light wave returns to it's...
48. ### Determining the Quality factor of resonator

Respected members, PLEASE help me in determining quality factor of a piezoelectric rectangular plate MEMS RESONATOR in COMSOL multiphysics.there is a need to define some 'damping'.where should i define that.. PLS HELP ME ITS URGENT thank you and best
49. ### Photon Average Energy in a Cavity Resonator

The rms EM field within a cavity resonator, excited in a single resonant mode by a current probe of fixed rms amplitude, is known to rise linearly with time; eg. http://www.jpier.org/PIER/pier78/15.07090605.Wen.pdf", sections 5.2, 5.3, fig's. 6, 10. (Normally it is a fixed driving voltage...
50. ### What is a transmission line resonator ?

Hi, I'm learning something on circuit QED, which has a part called transmission line resonator (TLR). It plays the role of a cavity. However, I don't get how it works that way. Can anyone give some help ? Thanks in advance !