Topic
Crystal oven
About: Crystal oven is a research topic. Over the lifetime, 955 publications have been published within this topic receiving 10380 citations. The topic is also known as: oven-controlled crystal oscillator & OCXO.
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21 Jun 2016
TL;DR: A cyclical pulsing oscillator with a pulse repetition rate close to a crystal resonant frequency in an oscillator provides more useful start-up energy to the crystal oscillator circuit and thus provides much faster startup time as discussed by the authors.
Abstract: A cyclical pulsing oscillator having a pulse repetition rate close to a crystal resonant frequency in an oscillator provides more useful start-up energy to the crystal oscillator circuit and thus provides much faster start-up time. The start-up pulsing oscillator runs for a number of cycles or until the crystal oscillator amplitude as built up to a desired value. The pulsing oscillator may have a repetition rate of from about one-third to about one-half the crystal resonant frequency, thus providing more useful start-up energy to the crystal oscillator circuit.
12 May 2013
TL;DR: In this paper, the authors presented results of numerical and experimental investigation of the non-critical phase-matching SHG in LiB3O5 (LBO) crystal with a constant axial temperature gradient.
Abstract: Summary form only given. Efficiency of second-harmonic generation (SHG) of broadband light pulses is limited by chromatic dispersion of a nonlinear crystal. The group velocity mismatch between first and second harmonic pulses results diminishing overlap between pulses as they propagate in a nonlinear crystal. Particularly, when fundamental pulses are chirped (phase-modulated), the group velocity mismatch causes loss of phase-matching even before complete walk-off of pulse envelopes occurs. This limits the optimal crystal length and, as a result, overall conversion efficiency. In order to maintain the high conversion efficiency in a shorter crystal, pulse irradiance has to be increased. However, the pulse irradiance is limited by the crystal damage threshold. Thus, achieving the high conversion efficiency of broadband pulses is not a trivial task, especially when the pulses are not bandwidth-limited. Concept of improving the frequency conversion bandwidth by inducing a constant temperature gradient along a nonlinear crystal was proposed by R.A. Hass. The phase-matching wavelength of the non-critical phase-matched SHG in a nonlinear crystal depends on the crystal temperature. When a constant temperature gradient is imposed along the crystal, the phase-matching conditions for different wavelengths are satisfied at different positions along the crystal. This explains the broad conversion bandwidth achievable by this method. However, in order to fully analyze possible improvements in the conversion efficiency achievable by this method, numerical calculations are required. In this contribution, we present results of numerical and experimental investigation of the non-critical phasematched SHG in LiB3O5 (LBO) crystal with a constant axial temperature gradient. Numerical calculations were accomplished by integrating (in the plane-wave limit) coupled-wave equations using a split-step technique in which pulse propagation is handled by the fast Fourier transform methods, whereas nonlinear interaction is handled by Runge-Kutta integration. According to the numerical results, by using the SHG method with a constant axial temperature gradient for broadband (phase-modulated) picosecond pulses, higher conversion efficiency could be achieved than using conventional SHG method, when the crystal temperature is uniform. For the experiment, a special crystal oven with two independent heaters at opposite ends of the crystal was developed. Second harmonic of the 12 nm bandwidth (1064 nm center wavelength) 11 ps pulses was generated in the 30 mm long LBO crystal with axial temperature gradient. At pulse energy of 2.5 μJ, the conversion efficiency was higher than 65 % and the whole fundamental spectrum was converted to second harmonic. The obtained experimental results were in agreement with results of our numerical calculations. According to our results, this SHG method can be attractive for implementation in practical applications, because of the high-efficiency broadband operation, robust design and simple wavelength tuning. Particularly, when using the LBO nonlinear crystal, a single frequency conversion module can be designed suitable for operation in the whole ytterbium-doped fiber laser gain wavelength range.
02 Sep 2001
TL;DR: This paper shows most of the results obtained so far by the method of extracting signals from thickness shear mode resonator sensors and discusses the general performance, advantages and disadvantages as well as comparison with the standard frequency measurement technique.
Abstract: This work illustrates an alternative method of extracting signals from thickness shear mode resonator sensors. The basic idea consists of modulating the voltage supply of an oscillator circuit driven by a quartz element. The sensor signal can then be obtained measuring the time decay of the output signal in the off state, where some energy, stored in the on state, is released in the form of a damping oscillation. It has been experimentally proven that the time decay in the off state can be reproducibly related to the quartz loading by a remarkable sensitivity function. This paper shows most of the results obtained so far by this technique and discusses the general performance, advantages and disadvantages as well as comparison with the standard frequency measurement technique.
01 Nov 2007
TL;DR: In this paper, an element retention mechanism was designed to safely maintain the quartz crystal resonator for the external force with flat structure, which has the characteristic that the resonance frequency changes by the external forces.
Abstract: To achieve high sensitivity, high-speed response, and wide range, a force sensor with quartz crystal resonator, which has the characteristic that the resonance frequency changes by the external force, is fabricated with a simple structure. AT-cut quartz crystal is employed due to its superior temperature and frequency stability. Because it is weak for the quartz crystal to the impact, bend, and tension, an element retention mechanism was designed that safely maintains the quartz crystal resonator for the external force with flat structure. In this study, a novel retention mechanism of the quartz crystal resonator for the flat structure was fabricated and analyzed. The proposed force sensor is flat, small, and sensitive to be applied to several usages such as medical treatment and dynamic contact force detection of human.
TL;DR: In this paper, a method of measurement is used whereby variation in frequency of a high frequency oscillator can be measured easily to a fraction of a part in a million, where the audible difference tone produced by a harmonic of a constant, high-frequency oscillator and a second oscillator is compared to the tone of a variable, calibrated audio frequency oscillators.
Abstract: A method of measurement is used whereby variation in frequency of a high frequency oscillator can be measured easily to a fraction of a part in a million. The audible difference tone produced by a harmonic of a constant, high frequency oscillator and a harmonic of a second oscillator is compared to the tone of a variable, calibrated audio frequency oscillator. Any change of the frequency of the second high frequency oscillator is measured to a fraction of a cycle per second. This method of measurement is used to determine the effects of temperature and pressure on the frequency of a piezo‐electric oscillator. The temperature effect is of the order of 20 parts per million per degree centigrade while the pressure effect is of the order of only 6 parts per million per atmosphere.