Rb lamp is a very critical component of the Rb atomic clock’s Physics Package. The Rb lamp’s performance is very sensitive to temperature and its stability. In this paper we discuss the behaviors of Rb Lamp with temperature. The Rb lamp exciter power and temperature of Rb bulb are very important parameters in controlling the performance of the Rb Lamp. It is observed that at temperatures beyond 110° C, the lamp mode changes from the ring to red mode resulting in abnormal broadening of emission lines and self reversal. The results of our studies on spectral analysis of Rb lamp under various operating conditions are reported in the paper.
Rb lamp is a very critical component of the Rb atomic clock’s Physics Package. The Rb lamp’s performance is very sensitive to temperature and its stability. In this paper we discuss the behaviors of Rb Lamp with temperature. The Rb lamp exciter power and temperature of Rb bulb are very important parameters in controlling the performance of the Rb Lamp. It is observed that at temperatures beyond 110° C, the lamp mode changes from the ring to red mode resulting in abnormal broadening of emission lines and self reversal. The results of our studies on spectral analysis of Rb lamp under various operating conditions are reported in the paper.
Since the 1960s, alkali-based RF discharge lamps have been used as frequency-stable light sources due to their reliable performance [1]. However, it is often reported that rubidium (Rb) lamp-based standards suffer from lamp-related frequency ageing phenomena such as light-shift effects [2], [3]. To understand this behaviour, we are characterising a commercial Rb-based RF discharge lamp over extended periods and will present an analysis of data collected so far. Electrical and optical measurements on a Rb lamp are presented here after about 40 days of monitoring. The output of the lamp was coupled into an optical fibre to observe its emitted light characteristics with an optical spectrum analyser. Optical spectra results indicated that the lamp had substantial buffer gas content. The lamp spectra exhibited various buffer gas excitation lines as well as strong Rb excitation lines of 780.0 nm (D2 line) and 794.8 nm (D1 line). Subsequently, the lamp was monitored for output optical power, temperature, and electric current dynamics in a laboratory environment. During monitoring, sudden changes in light output were observed along with longer term trends. From previous studies, we can expect that temporal changes in the light intensity of the lamps may lead to observable frequency fluctuations in an atomic clock [4].
Rubidium electrodeless lamp is one of the core components of rubidium atomic frequency standard. It plays the role of optical pumping and quantum state preparation, and realizes the particle number inversion between two ground states of rubidium atoms. The RF excitation frequency affects the effective light spectral distribution of rubidium electrodeless lamp, and then determines the pumping efficiency and the limiting frequency stability of rubidium atomic frequency standard. In this paper, the influence of RF excitation frequency on the spectral characteristics of rubidium electrodeless lamp can be optimized based on power compensation. It is found that there is a sensitive dependence between the heating rate and the excitation frequency of the rubidium electrodeless lamp, and the excitation frequency range corresponding to the turning point of the maximum heating rate was given experimentally. When the input power and the bubble wall temperature remain unchanged and the rubidium electrodeless lamp is in the ring-mode state, the spectral characteristics have a depression at the optimum resonance frequency. Therefore, the excitation frequency of the rubidium electrodeless lamp should be properly pulled to 5~9 MHz from the optimum resonant point, which can optimize the spectral characteristics of the rubidium electrodeless lamp and can improve the frequency stability of the rubidium atomic clock.
Rubidium spectral lamp is one of the critical parts in a rubidium atomic frequency standard (RAFS). The light emitted from the spectral lamp contains two components, one is the useful component, which contributes to the atomic transition signal, and the other is the useless component, which acts only as the light noise. In order to improve the signal-to-noise ratio of the frequency locking loop of a RAFS, and therefore to obtain a highly stable RAFS, it's very important to enhance the useful light component and suppress the useless component. In the present work the light spectra of the three commonly used rubidium spectrum lamps with bulbs separately filled with buffer gases argon, krypton and xenon were obtained by means of a monochromator. The spectra were analyzed and the methods to enhance useful light intensity and reduce useless light intensity were discussed. Results showed that the useful light intensity strongly depends on the types of buffer gases and the bulb temperature. In the whole range of bulb temperature, the Xe lamp had the highest useful light intensity among the three lamps. The Kr lamp showed a higher useful light intensity than the Ar lamp at low bulb temperature, while at high bulb temperature the Ar lamp showed a higher useful light intensity than the Kr lamp. Analysis also indicates that the light noise of a rubidium spectrum lamp can be effectively minimized by adopting suitable light filtering technique.
We present our recently experimental results on a DFB laser diode pumped Rubidium atomic frequency standard. Our experiment was based on a homemade lamp-pumped Rubidium frequency standard with the discharge lamp assembly removed. In the experiment, we first locked a DFB laser diode to the87Rb cycling transition (5S1/2, F=2→5P3/2, F=3) by means of saturation absorption locking technique. After that, we optimized the parameters carefully related to the clock performance, such as temperature of the physical package, amplitude of the modulation signal for the laser locking. The preliminary short-term stability of our clock is measured 5.25×10−12τ−1/2(1s<τ<100s).
This paper deals with the experimental studies of the rubidium (Rb) spectral lamp for the purpose of getting an excellent pumping light source for a Rb gas cell type frequency standard, or for a Rb microwave maser. Some of Rb lamps containing Ne, Ar, Kr, and Ne-Ar as a carrier gas were made by way of experiment. In order to observe the hyperfine spectrum of D1line, the Fabry-Perot type scanning interferometer was made, which is driven electrostrictively. The hyperfine components of D1line were resolved successfully. It was observed that the line which is used as a pumping source became intense as the lamp temperature was raised, and it began to be dipped and decrease, however, over the definite temperature. Also observed was that this optimum temperature differs from the temperature at which the integrated intensity of D1line shows a maximum.
The temperature dependence of the spectral profile of the 87Rb D1 line (λ = 794.8 nm) observed by a Fabry-Perot interferometer has been discussed by considering the self-absorption mechanism in the lamp. The Rb lamp is assumed to be composed of two separated portions: One is a spherical core of emitting Rb atoms and the other is an outer layer of the same kind of absorbing atoms surrounding the core. The temperature dependence of the emitted light intensity, intensity difference between two hyperfine peaks, and asymmetry of the self-absorbed profiles are systematically explained in the temperature range of 75 to 125°C. The equivalent absorbing atom layer near the lamp surface is estimated to be 0.5 mm in this model.