Amplitude response of Fabry-Perot frequency discriminators

The amplitude noise responses of optical-frequency-discriminating systems, based on Fabry-Perot cavities with intensity noise compensation, are analyzed considering also the effect of the resonator transient. From the point of view of amplitude noise immunity, systems based on transmission or reflection alone behave in a quite similar way within the discriminator bandwidth, whereas a proper combination of both these signals not only increases the sensitivity to frequency noise but also allows for higher rejection to amplitude noise.     

High-frequency-stability diode-pumped Nd:YAG lasers with the FM sidebands method and Doppler-free iodine lines at 532 nm

The FM spectroscopy technique has been applied to two frequency-doubled Nd:YAG lasers to achieve absolute frequency stabilization against the hyperfine structure components of the rovibronic P(54) 32-0 iodine line at 532 nm. A fractional frequency stability of 2 x 10(-13) tau(-1/2) has been obtained for integration times in the range of 1 ms < tau < 10 s. For longer integration times the stability level remains below 10(-13), reaching a minimum value of 4.6 x 10(-14) at 100 s. This high stability level is, to our knowledge, the best value achieved against iodine lines by this locking method and for a fully transportable system.     

Comparison of different fast modulation techniques for FIR laser stabilization

In the first part of this paper the characteristics of frequency deviation and modulation bandwidth required for phase-locking optically pumped far infrared lasers to reference synthesized signals are examined. Then different fast modulation techniques suitable for this purpose are discussed pointing out their particular features. Experimental results concerning laser frequency modulation by Stark effect, injection locking and electrically variable reactances (e.g Schottky diodes, plasma cell) are reported and compared.     

Tentative approach to the design of waveguide-below-cutoff bandpass filters

This letter deals with a theoretical approach to the waveguide-below-cutoff bandpass filter. An equivalent circuit of the elementary section of the filter is used to derive the attenuation and bandpass properties. In order to explain some discrepancies between theoretical and experimental data, a more sophisticated circuit is introduced.     

亨利·巴瓦(Henri Bava)在中法园林文化论坛上的报告

亨利·巴瓦先生通过介绍其承担的6个项目（瑞士日内瓦扬特基金会花园、法国尼姆市中学校园庭院设计、混合停车场设计、魔水花园、绿色都市、巴黎市中心集市改造工程），向人们阐述了他的设计观念，他认为土壤是进行设计工作的基质和源泉，园林设计不仅要考虑土壤本身的含义，更要由表及里去考虑各个时期中自然、历史、文化对土壤的影响所形成的地貌物的整体。他通过实例告诉风景园林师要深入挖掘发现设计区域内一些未知的、看不见的东西，从而在整体上把握我们的设计。     

Frequency measurement of the CO2R1(32) line with respect to a 3.39μm He22Ne/CH4 standard

The frequency of the R_I(32) CO₂ line has been measured with respect to a 3.39 μm He²²Ne laser stabilized to the F₂ ⁽²⁾ P(7) transition in thev ₃ band of CH₄. The value obtained isv=29477160862±12 kHz, in good agreement with the only value reported in the literature. Using the available data of the R_I(32)-R_I(30) (difference) frequency, the following value can be derived for the R_I(30) line: ν=29442483320±18 kHz.     

Measurements of near-infrared frequency mixing by metal-semiconductor point-contact diodes

The performances of metal-semiconductor point-contact diodes as mixers in the near-infrared region were tested. Preliminary experiments were performed in order to phase-lock two diode lasers at 850 nm a few hundred gigahertz apart. GaSb, InAs, and InSb as semiconductor layers were used. The frequency bridge between the two lasers was covered by a Gunn diode frequency locked to a 1-GHz oscillator. A novel phase-lock circuit was tested on two diode lasers 72 GHz apart.