Design and development of an external cavity diode laser for laser cooling and spectroscopy applications

[摘要] External cavity diode lasers are used increasingly as sources of light in applications ranging fromindustrial photonic systems to basic laboratory research on the interaction of light and atoms.External cavity diode lasers offer more stable output frequency and narrow spectral bandwidththan the typical free-running diode lasers. These characteristics are achieved by exploiting thesensitivity of diode lasers to external optical feedback. In this study the design and developmentof an external cavity diode laser system for future applications in spectroscopy and laser coolingof rubidium atoms is presented. The external cavity diode laser including mechanical componentsand control electronics of the system is developed from basic components. The system uses frequencyselective optical feedback from a diffraction grating in a Littrow configuration to providecollimated, narrow-band, frequency tunable light near 780 nm. The external cavity diode laser isdesigned to increase the mode-hop-free frequency tuning range, and allow accurate frequency tuningand stabilisation. A low-noise current source and a temperature controller for thermal stabilitywere developed as part of the system since the output frequency changes with temperature andcurrent. The temperature controller is optimised experimentally for the thermal characteristics ofthe external cavity. An electronic sidelock servo circuit for frequency locking of the external cavitydiode laser to an external reference for long term frequency stabilisation is proposed and discussed.The servo circuit electrically controls the grating tilt and the current through the diode laser inorder to lock the frequency of the diode laser. The external cavity diode laser is optimised andcharacterised near 780 nm. Results obtained in this study indicate that the external cavity diodelaser is suitable for future applications in spectroscopy and laser cooling of neutral rubidium atoms.

[发布机构] Stellenbosch University