Frequency drift

About: Frequency drift is a research topic. Over the lifetime, 5054 publications have been published within this topic receiving 56191 citations. The topic is also known as: chirp rate.

Frequency control of tunable lasers using a frequency-calibrated λ-meter in an experiment on preparation of Rydberg atoms in a magneto-optical trap

Abstract: A new technique is proposed and applied to study the frequency drift of an external-cavity semiconductor laser, locked to the transmission resonances of a thermally stabilised Fabry–Perot interferometer. The interferometer frequency drift is measured to be less than 2 MHz h-1. The laser frequency is measured using an Angstrom wavemeter, calibrated using an additional stabilised laser. It is shown that this system of laser frequency control can be used to identify Rydberg transitions in ultracold 7Li atoms.

Frequency Locked Single-Mode Optoelectronic Oscillator by Using Low Frequency RF Signal Injection

Abstract: We propose a new injection-locked optoelectronic oscillator (OEO) which is locked by a low frequency RF signal and without adding high speed devices. From a low frequency modulated optical carrier, the injection-locking effect in a Fabry-Perot laser diode is able to generate and selectively amplify one high order harmonic component, which is subsequently injected into a single-loop OEO to lock one of the oscillation modes. This process can improve the injected signal quality and simultaneously implement a single-mode OEO with precise oscillation frequency. In the experiment demonstration, a 20-GHz single-mode OEO locked by a 1-GHz RF signal is obtained. The measured side-mode suppression ratio is 65 dB and the phase noise at 1-kHz frequency offset is -94.7ndBc/Hz.

A 50-GHz silicon IMPATT diode oscillator and amplifier

Abstract: Recent experimental observations on a silicon impact avalanche transit-time diode oscillator and amplifier CW-operated at 50 GHz are presented. 1) CW oscillation power of 100 mW was obtained at an overall efficiency of 2 percent. The oscillation frequency was continuously tunable over a 1.3-GHz range by a sliding short. 2) Phase-locking has been achieved with a maximum normalized gain-bandwidth product of 0.1. The minimum locking signal power required for a 500-MHz locking bandwidth was 20 dB below the oscillator output. 3) Electronic tuning of the oscillator frequency was demonstrated by placing a millimeter-wave varactor diode in the tuning circuit. The output frequency versus the bias voltage on the varactor diode was linear with maximum frequency deviation of 300 MHz. Frequency modulation of the oscillator by driving the varactor with a sinusoidal source was obtained at a modulation frequency of 50 MHz. 4) Stable amplification with 13-dB gain was obtained, centered at 52.885 GHz with a 3-dB bandwidth of 1 GHz. The maximum output power obtained was 16 mW. Higher gain of about 17 dB was obtained at a reduced bandwidth. The noise figure of the amplifier was 36 dB. Equivalent circuits for the oscillator and the amplifier are derived. The calculated results agree reasonably well with the experimental observations.

Phase-locked loop oscillator

Abstract: In a typical phase-locked loop oscillator circuit including a voltage controlled oscillator and a reference frequency source, from each of which a signal is derived and the phases of these two signals are compared in a phase detector, the output of which is applied through a loop filter to a frequency modulation input of the voltage controlled oscillator, so that the frequency of the voltage controlled oscillator is precisely controlled by the reference frequency; an improvement which comprises a maximum phase error detector which determines a maximum permitted phase error between the two inputs to the phase detector, and a phase error corrector circuit which, in response to the presence of a maximum permitted phase error, will shift the phase of one of the two signals applied to the phase detector relative to the source of that signal, such as to hold the phase error into the phase detector within the permitted maximum. This causes the voltage controlled oscillator to shift its frequency to the lock-up frequency in a smooth and steady manner. The improvement prevents operation of the system from being disrupted when the circuit falls out of lock, such as when the modulating signal has large low frequency components. The circuit also includes an out-of-lock detector which responds essentially instantaneously to an in-lock and out-of-lock condition and a means for altering the characteristics of the loop filter in order to minimize the effect of the out-of-lock condition upon the voltage controlled oscillator.