Tianchu Li

External cavity diode laser with kilohertz linewidth by a monolithic folded Fabry–Perot cavity optical feedback

We present a extended-cavity diode laser (ECDL) with kilohertz linewidth by optical feedback from a monolithic folded Fabry-Perot cavity (MFC). In our experiments, an MFC replaces the retroreflecting mirror in the traditional ECDL configuration. Beat-note measurements between this MFC-ECDL and a narrow-linewidth reference laser are performed and demonstrate that the linewidth of this MFC-ECDL is about 6.8 kHz. Phase locking of this MFC-ECDL to the reference laser is achieved with a unity gain as small as 10.2 kHz.

100-Hz Linewidth Diode Laser With External Optical Feedback

We present a narrow-linewidth diode laser with optical feedback from a high-finesse two-mirror nonconfocal cavity. The lasers full-width-at-half-maximum linewidth is reduced to 100 Hz, and its instantaneous linewidth to 30 Hz in the Lorentzian fitting. To the best of our knowledge, it is the narrowest linewidth ever achieved with the optical feedback method. The laser phase noise has been significantly reduced by more than 50 dB in the frequency range from 10 Hz to 10 kHz. Our experiment demonstrates the efficient laser linewidth reduction and phase noise suppression by the optical feedback technique.

High-finesse cavity external optical feedback DFB laser with hertz relative linewidth

We report hertz level relative linewidth distributed feedback diode lasers with external optical feedback from a high finesse F-P cavity, and demonstrate the efficient phase noise suppression and laser linewidth reduction of the optical feedback technique. The laser phase noise is dramatically suppressed throughout the measurement frequency range. Especially at the Fourier frequency of 17 kHz, approximately the linewidth of the F-P reference cavity, the laser phase noise is significantly suppressed by more than 92 dB. Above this Fourier frequency, the noise maintains a white phase noise plateau as low as -124.4 dBc/Hz. The lasers FWHM linewidth is reduced from 7 MHz to 4.4 Hz, and its instantaneous linewidth is 220 mHz in the Lorentzian fitting.

Quasi synchronous tuning for grating feedback lasers

A general analytical form of the round trip phase shift in grating feedback diode lasers is proposed. Using the new form, it is obvious that the round trip phase shift can be independent of rotation angle in first order approximation when only one restriction condition is met. We call this the quasi synchronous tuning (QST) condition. In the QST region, a considerably large mode hopping free tuning range can be obtained. An adjustment structure with only one freedom is needed to accurately find and locate the quasi synchronous pivot, which is not strictly confined on the grating surface and its extension. It means that the external cavity diode lasers design can be easier and the laser can be more stable and reliable.

High-finesse F-P cavity external optical feedback narrow linewidth diode laser

We present a narrow linewidth laser by optical feedback from a high-finesse F-P cavity. The cavity transmission feeds back to the laser diode by the external ring path. With a low servo bandwidth system, the feedback phase is compensated for maintaining the optical feedback operation. The linewidth of the optical feedback laser is reduced to 100 Hz, and the laser frequency noise in frequency range of 1 Hz to 10 kHz is suppression over 50 dB. It experimentally demonstrates the excellent characteristics of optical feedback technique.

Magic Wavelength Measurement of the

We report on the magic wavelength measurement of our optical lattice clock based on fermion strontium atoms at the National Institute of Metrology (NIM). A Ti:sapphire solid state laser locked to a reference cavity inside a temperature-stabilized vacuum chamber is employed to generate the optical lattice. The laser frequency is measured by an erbium fiber frequency comb. The trap depth is modulated by varying the lattice laser power via an acousto-optic modulator. We obtain the frequency shift coefficient at this lattice wavelength by measuring the differential frequency shift of the clock transition of the strontium atoms at different trap depths, and the frequency shift coefficient at this lattice wavelength is obtained. We measure the frequency shift coefficients at different lattice frequencies around the magic wavelength and linearly fit the measurement data, and the magic wavelength is calculated to be 368554672(44) MHz.

^{87}

We present a laser system design for an absolute gravimeter based on 87Rb atom interferometer. By skillful design, lasers with 9 different frequencies are based on two diode lasers including tapered amplifier. Two electrical feedback systems are used for laser frequency stabilization and the Raman lasers generation respectively. All other lasers are based on two Raman lasers and realized with frequency shift by acoustic optical modulators. This laser system not only has the compact and simple construction, but meets all requirements for laser power and frequency controlling for the atom interferometer. It has the characteristic of reliability and integrity.

Sr Optical Lattice Clock at NIM

Abstract not available