Phonon Maser Research Articles

Phonon maser stimulated by spin postselection

In a sequence of single spins interacting longitudinally with a mechanical oscillator, and using the micromaser model with random injection, we show that after an appropriate post-selection of each spin, a phonon laser analog with Poisson statistics is created with nearly perfect coherence, evidenced by the second order coherence function that goes asymptotically to one. The non-linear gain of the system depends crucially on the properly post-selected spin state as well as the pump. Our model and results suggest that the mechanism of interaction followed by a post-selected state or partial trace (common in laser/maser theory) of the spins may create the coherent vibrational radiation. However, for situations where the mechanical losses are high and it is imposible to decrease these, then the heralded post-selection can be the only resource to get phonon lasing if compared to the partial trace operation. These ideas and results may be useful for further theoretical and technical developments.

Heating of Heavy Water by Acoustic Wave Propagation in Magnetic Field and Phonon Maser Action of Deuteron

Heating by less than 10°C of heavy water was observed at room temperature upon the propagation of acoustic waves of 6 MHz with intensity of about 2 W/cm 2 during the scanning of a magnetic field from 800 to 1000 mT. A control experiment with light water did not show the heating. As a quantitative explanation of this heating, the “spin-flip phonon maser” action of deuterons due to the thermal Raman process of spin-phonon coupling is considered. Good agreement with the experimental result was obtained. The 6 MHz acoustic waves induce the pumping transitions of the nuclear spin system.

Mode-locked CdS phonon masers — optical reconstruction of strain profiles

The strain profile in a mode-locked phonon maser has been reconstructed by applying spatial and temporal filtering techniques to optical signals produced by laser diffraction.

Nanosecond acoustic strain pulses from CdS phonon masers

Observations of nanosecond strain pulses generated by a mode-locked CdS phonon maser are reported. Peak strains exceeding 5 × 10 -5 have been measured. An analogy is drawn between the observed mode-locked operation and a repetitive pulse generator.

Nanosecond acoustic strain pulses from CdS phonon masers

Nanosecond acoustic strain pulses, generated by a mode‐locked CdS phonon maser, have been observed through application of optical diffraction and spatial filtering techniques. Peak strains exceeding 5×10−5 have been measured. An analogy drawn between our device and a repetitive pulse generator has provided some insight into mode‐locked phonon maser operation. [Work supported by the National Research Council and Defense Research Board of Canada.]

Light Diffraction Studies of CdS Phonon Masers: Off-Axis Cavity Structures

Light diffraction experiments on CdS phonon masers whose cavity normal is oriented at 15, 30, 45, 60, and 75° to the crystallographic c axis are presented and compared with theory. It is shown that in general the acoustic waves do not propagate along the direction of the cavity normal. An interpretation of the observations requires that one takes into account the acoustic anisotropy and the effect of mode conversion at the cavity walls.

Light Diffraction Studies of CdS Phonon Masers: Polarization Effects

We have studied polarization effects associated with the diffraction of light from ultrasonic waves present in c-axis phonon masers. Experimental data are presented and compared with a theory which assumes that the ordinary and extraordinary components of the light beam are diffracted coherently.

Ultrasonic wave propagation in CdS phonon maser structures : Vrba, J., Haering, R.R., Canadian journal of physics51 (15 July 1973) 1350–1358

Ultrasonic wave propagation in CdS phonon maser structures : Vrba, J., Haering, R.R., Canadian journal of physics51 (15 July 1973) 1350–1358

Voltage modulation of CdS phonon masers

We have investigated the voltage tuning of b-axis CdS phonon masers. Voltage modulation is found to be a fairly complex phenomenon involving amplitude as well as frequency modulation of the phonon maser output. Near threshold, the frequency modulation is typically of the order of 10 kHz/V. The response is flat up to frequencies of the order of the reciprocal of the acoustic transit time. At the higher driving voltages, the tuning is reduced. The device appears promising as a FM communications transmitter.

Ultrasonic Wave Propagation in CdS Phonon Maser Structures

An analysis of phonon maser action in CdS is given which includes the complications arising from the presence of off-axis ultrasonic waves. The treatment includes the angular variation of the velocity of sound and of the piezoelectric coupling constant and takes account of mode conversion at the cavity walls. Numerical results are given for CdS maser structures.

Light Diffraction Studies of CdS Phonon Masers

Light diffraction experiments on c- and b-axis CdS phonon masers are presented and compared with the theoretical analysis presented in the previous paper. It is shown that in general the active acoustic waves do not propagate along the normal to the plane parallel sides of the crystal. The agreement with theory is good. Strain amplitudes as large as 10−4 have been observed.

Wave Propagation in a Dispersive and Emissive Medium

Recently a measurement of the velocity of longitudinal ultrasonic waves propagating through a phonon maser amplifier showed that the pulse traveled with the maximum or cutoff velocity at resonance. With an approximate dispersion rule for a homogeneously broadened spin-resonance transition, the propagation of the wave is analyzed using a method for the asymptotic expansion of Fourier-type integrals. This analysis, contrary to earlier studies, indicates that the pulse observed, or at least the leading edge of that pulse, was an amplified precursor (transient response). For a sinusoidal imput signal, the asymptotic wave form at a given position is given for all possible values of the time.

A proposed broad-band phonon maser

This letter proposes a pulsed microwave phonon maser which, operating at 2°K, should have a gain of a few dB/cm and a bandwidth of about 300 Mc/s.

Basic Equations and Conservation Theorems for the Electrostriction Phonon Maser

Brillouin scattering of light by phonons and the phonon maser are usually described in terms of an approximate set of linearized equations. Here we give a more exact set of equations for a lossless polarizable fluid; only relativistic effects are disregarded. When these equations are linearized and higher order terms in the ratio of sound speed to light speed are disregarded, they reduce to the customary set of equations. The more exact equations permit the derivation of the law of conservation of energy with a simple physical interpretation. From these equations the Manley-Rowe relations and other conservation laws also follow relatively easily.

The phonon maser

Abstract : The report is a proposal for a c.w., continuously tunable, phonon maser. The mechanism is quite analogous to optical pumping schemes, utilizing a double pump to preferentially populate an excited state of a paramagnetic ion.

Quantum Approach to Amplification of Optical Phonons in Semiconductors

It is shown by using a quantum-mechanical treatment that, in semiconductors with some ionic character, optical phonons can be amplified via their interaction with conduction electrons. The amplification of the optical phonons occurs when the drift velocity of the conduction electrons exceeds the phase velocity of the optical phonons. Both longitudinally and transversely polarized optical phonon modes are amplified via the electron-phonon interaction when the quantum treatment given is valid. The amplification of the optical phonon modes can be viewed as a phonon maser process, with the external drift field inverting the electron population. When the drift velocity of the electrons exceeds the optical-phonon phase velocity, the number of electrons that will emit optical phonons exceeds the number that will absorb optical phonons. The result is a net gain for those optical phonon modes whose phase velocity $s=\frac{\ensuremath{\omega}}{q}$ satisfies the condition ${V}_{d}>S$.

Interaction of phonons with iron-group ions

The interaction of phonons with paramagnetic spin systems is best characterized by coupling constants which relate the energy shift in the spin system to the strain introduced into the lattice. The theory of spin-phonon interactions is reviewed, and the coupling constants, as experimentally obtained, are compared to those which are most conveniently calculated. Generally, the results calculated on the basis of the point-charge theory are in reasonable agreement with the experimental results. A number of special topics involving spinophonon interactions are discussed, including double quantum detection of phonons, propagation in a dispersive medium, and the phonon maser.

Sound waves amplified by phonon maser effect

Sound waves amplified by phonon maser effect