UNIDEF   23986
UNIDAD DE INVESTIGACION Y DESARROLLO ESTRATEGICO PARA LA DEFENSA
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Laser Frequency Reference Locked to Rb D2 Transition Controlled by FPGA Lock-In Module
Autor/es:
MARCELO A. LUDA; JORGE CODNIA
Lugar:
Pucón
Reunión:
Congreso; VII Reunión Iberoamericana de Óptica y X Encuentro Latinamericano de Óptica, Láseres y Aplicaciones (IX RIAO/XII OPTILAS); 2016
Resumen:
External cavity diode lasers (ECDL) are a versatile sources of coherent light with high efficiency that can achieve several nanometer of wavelength tunning [1,2]. This kind of lasers find applications in ultra high resolution spectroscopy, metrology and coherent control of electronic states of atom gas or isolated trapped ions. Most of these applications requires careful control of several variables at the same time and the use of an external reference to stabilize the wavelength of the emitted light. For example, in metrology applications is common to lock the laser wavelength to Rubidium or Cesium transitions to provide absolute reference for atomic clocks or optical frequency references [3]. The lock is made using a lock-in technique, modulating the wavelength and de-modulating the transmitted signal through a gas cell, using the de-modulated signal as a first derivative detector. A feedback scheme is used to correct the drift from the transition and lock the laser [4].A complete control of the laser involves a temperature control, a current control and a control for the position of a diffraction grating, made through a piezoelectric transducer (PZT) [2]. In most of the commercial implementations each of this drivers are controlled from others modules using voltage signals that modulates the wavelength, de-modulates the transmitted signal and builds the feedback signal to complete the lock-in scheme.In this work we present an ECDL laser locked to one of the hyperfine transitions of D2 line of Rubidium, suitable for use as an optical frequency reference. The drivers of diode current, temperature and PZT control are of own design [2]. The novel approach is the locking control module, implemented entirely with an FPGA programmable-logic module. The FPGA controls all the drivers using DAC voltage signals. It produces the wavelength modulation through the current signal, modulating up to 50 kHz, de-modulates the transmitted signal and implements the filters to build the feedback signal. The system was successfully tested locking hyperfine Rubidium transition using saturated absorption spectroscopy. The system is good enough to implement as a prototype to replace commercial lock-in modules in spectroscopy and atomic labs with only one centralized control modul.[1] K. B. MacAdam, A. Steinbach, C. Wieman, American Journal of Physics 60(12) 1098-1111 (1992).[2] M. Luda, J. Codnia, M. L. Azcárate, ANALES AFA Vol. 25 N2, 84-87 (2014)[3] J. Vanier, Applied Physics B 81(4):421-442 (2005)[4] Eric D. Black, American Journal of Physics 69, 79 (2001)