Design and construction of tapered amplifier systems for laser cooling and atom trapping experiments

Jayampathi Kangara, Andrew J. Hachtel, Matthew Gillette +9 more

We present plans for the construction and operation of a tapered optical amplifier (TA) system seeded by a single-mode, frequency-tunable, near-IR external-cavity diode laser. Our plans include machine drawings for the parts, electronic circuit diagrams, and information on prices and vendors. Instructions are provided on how to safely couple light into and out of the TA chip. Practical aspects of handling the chip are discussed as well. Because many cold atom experiments require light beams with Gaussian spatial profiles, measurements of the tapered amplifier light output through a single-mode optical fiber are presented as a function of seed intensity, polarization, and driving current.

Steven Chu, John E. Bjorkholm, Arthur Ashkin +1 more

R. A. Cole

The number density of cold atoms confined in a magneto-optical trap (MOT) is critically dependent on the intensity of the lasers used to cool the sample. To generate large optical powers while retaining the practicality of homemade external cavity diode lasers (ECDLs), a tapered amplifier (TA) system was designed and constructed to amplify the output of an existing 780 nm, continuous-wave ECDL. The amplifier’s performance is discussed in terms of its gain and power output. Under standard operating conditions, optical amplification of 12 dB is achieved, with a maximum power output of 0.75 W. The completed amplifier is installed into an existing MOT at Colby College, and its effect is analyzed in terms of the number density of trapped samples of rubidium-85. MOT measurements are given demonstrating an increase in these number densities by a factor of ten. We conclude with initial results to quantify the amplifier’s effect on the dynamics of ultra-cold plasmas created from the trapped atom samples.

Shan Zhong

Wei Dong, Haixia Chen, Xiong De-Zhi +2 more

We have developed a semiconductor laser system used in 40K-87Rb trapping and cooling experiment. The laser diode system is composed of three external cavity diode lasers and four injection diode lasers and a tapered amplifier. Four laser beams used for 40K and 87Rb cooling and repump lights are obtained by using acoustic optic modulators to offset the frequencies from the three external cavity diode lasers. Four light beams with different frequencies are injected into four slave lasers for injection locking. Then Rb cooling light, K cooling light and K repump light are injected into a semiconductor tapered amplifier in a master oscillator-power configuration. This configuration is flexible and stable and can simultaneously produce the cooling and repump light for 40K and 87Rb trapping and cooling experiment.

Philip H. Jones, Onofrio M. Maragò, Giovanni Volpe