Author Affiliations
Abstract
State Key Laboratory of Precision Measurement Technology and Instruments, Department of Precision Instrument, Tsinghua University, Beijing 100084, China
A frequency-degenerate cavity (FDC) is the resonator that the ratio of transverse and longitudinal mode frequency spacings is a simple rational number. When an optical resonator is close to the FDC, transverse-mode-locking (TML) takes place with drastic changes of laser mode. We report for the first time, to the best of our knowledge, the multi-frequency emission and spectral modulation effects coupled with TML in FDC. The Yb:CaGdAlO4 (Yb:CALGO) crystal with large gain bandwidth was used as a gain medium in an off-axis-pumped hemispherical FDC for realizing broadband emission. Interestingly, the spectrum can transform from a single smooth packet shape to a multi-peak structure; meanwhile, the transverse pattern accordingly transforms into some exotic wave-packet profiles through controlling off-axis displacement in a special degenerate state.
140.3410 Laser resonators 140.3518 Lasers, frequency modulated Chinese Optics Letters
2019, 17(3): 031404
Author Affiliations
Abstract
1 Key Laboratory of Time and Frequency Primary Standards, National Time Service Center, Chinese Academy of Sciences, Xi’an 710600, China
2 School of Astronomy and Space Science, University of Chinese Academy of Sciences, Beijing 100049, China
We demonstrate a proposal for making an ultrastable laser referenced to a multi-cavity, enabling a lower thermal noise limit due to the averaging effect. In comparison with a single-cavity system, relative frequency instability of the synthesized laser can be improved by a factor of the square root of the cavity number. We perform an experiment to simulate a two-cavity system with two independent ultrastable lasers. Experimental results show that the relative frequency instability (Allan deviation) of the synthesized laser is 5 × 10 16, improved by a factor of √2 from a single-cavity-stabilized laser.
140.4780 Optical resonators 120.4820 Optical systems 140.3518 Lasers, frequency modulated Chinese Optics Letters
2018, 16(12): 121403
Author Affiliations
Abstract
State Key Laboratory of Precision Measurement Technology and Instruments, Department of Precision Instruments, Tsinghua University, Beijing 100084, China
A simple and robust technique is reported to offset lock a single semiconductor laser to the atom resonance line with a frequency difference easily adjustable from a few tens of megahertz up to tens of gigahertz. The proposed scheme makes use of the frequency modulation spectroscopy by modulating sidebands of a fiber electro-optic modulator output. The short-term performances of a frequency offset locked semiconductor laser are experimentally demonstrated with the Allan variance of around 3.9×10 11 at a 2 s integration time. This method may have many applications, such as in Raman optics for an atom interferometer.
020.1335 Atom optics 140.3425 Laser stabilization 140.3518 Lasers, frequency modulated Chinese Optics Letters
2018, 16(5): 050201
Author Affiliations
Abstract
1 State Key Laboratory on Integrated Optoelectronics, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
2 School of Electronic, Electrical and Communication Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
3 Henan Shijia Photons Technology Co., Ltd., Hebi 458000, China
Based on the hybrid integration technology, an ultra-compact and low cost transmitter optical subassembly module is proposed. Four directly modulated lasers are combined with a coarse wavelength division multiplexer operated at the O-band. The bandwidth for all channels is measured to be approximately 3 GHz. The 112 Gb/s transmission is experimentally demonstrated for a 10 km standard single mode fiber (SSMF), in which an optical isolator is used for avoiding the back-reflected and scattered light to improve the bit error rate (BER) performance. A low BER and clear eye opening are achieved for 10 km transmission.
250.5960 Semiconductor lasers 140.3518 Lasers, frequency modulated Chinese Optics Letters
2018, 16(6): 062501
Author Affiliations
Abstract
1 Department of Instrument Science and Technology, College of Mechatronic Engineering and Automation, National University of Defense Technology, Changsha 410073, China
2 Interdisciplinary Center for Quantum Information, National University of Defense Technology, Changsha 410073, China
We present a compact, low-noise, and inexpensive optical phase-lock loop (OPLL) system to synchronize the frequency and the phase between two external cavity diode lasers. Based on a direct digital synthesizer technique, a programmable radio-frequency generator is implemented as the reference signal source. The OPLL has a narrow beat note linewidth below 1 Hz and a residual mean-square phase error of 0.06 rad2 in a 10 MHz integration bandwidth. The experimental test results prove the competent performance of the system, which is promising as a low-budget choice in atomic physics applications.
140.0140 Lasers and laser optics 140.3518 Lasers, frequency modulated 250.4745 Optical processing devices Chinese Optics Letters
2016, 14(5): 051403
Author Affiliations
Abstract
1 Department of Instrument Science and Technology, College of Mechatronic Engineering and Automation, National University of Defense Technology, Changsha 410073, China
2 Interdisciplinary Center for Quantum Information, National University of Defense Technology, Changsha 410073, China
We present a laser frequency locking system based on acousto-optic modulation transfer spectroscopy (AOMTS). Theoretical and experimental investigations are carried out to optimize the locking performance mainly from the view of the modulation frequency and index for the specific scheme of AOMTS. An FWHM linewidth of 63 kHz is achieved and the frequency stability in terms of Allan standard deviation reaches 1.4×10 12 at 30 s. The frequency shifting capacity is validated throughout the acousto-optic modulator bandwidth while the laser is kept locked. This work offers a different but efficient choice for applications calling for both stabilized and tunable laser frequencies.
140.3425 Laser stabilization 140.3518 Lasers, frequency modulated 020.1335 Atom optics 300.6380 Spectroscopy, modulation Chinese Optics Letters
2016, 14(12): 121401
Author Affiliations
Abstract
We present a high-precision optical phase-locking based on wideband acousto-optical frequency shifting. Increasing the modulating bandwidth stabilizes the loop at a high loop gain, thus improving phase correction capability. An optical phase-locked loop with a wide control bandwidth is constructed. The closed-loop residual phase error is only 0.26o or smaller than \lambda/1000. The loop exhibits excellent correction capability for high-frequency noises. The correctable frequency range reaches 35 kHz when the noise amplitude is +(-)\lambda/2, and becomes even wider for smaller noise amplitudes.
140.0140 Lasers and laser optics 140.3298 Laser beam combining 140.3518 Lasers, frequency modulated Chinese Optics Letters
2014, 12(2): 021402
Author Affiliations
Abstract
The cavity tuning characteristics of orthogonally polarized dual-frequency He-Ne laser at 1.15 \mu m are presented. Vectorial-extension model based on semi-classical laser theory reveals that cavity tuning characteristics are related to beat frequency, relative excitation, and type of Ne isotope. Distortions of cavity tuning curves become moderate with the increase of beat frequency because of the weakening of the crosssaturation effect. Distortions are enhanced with the increase of relative excitation because of the combined action of the self-saturation and cross-saturation effects. By adopting dual-isotope Ne instead of monoisotoplic Ne, distortions are reduced because of the misalignment between peaks of the self-saturation and net gain coefficients. The theoretical calculations are in good agreement with the corresponding experimental results.
140.1340 Atomic gas lasers 140.3430 Laser theory 140.3518 Lasers, frequency modulated Chinese Optics Letters
2012, 10(2): 021402
Author Affiliations
Abstract
A new method for laser-frequency stabilization by controlling the pulse setup time is presented. The frequency-stabilization system monitors the pulse setup time continuously, and controls it by adjusting the cavity length. Laser frequency is stabilized to the center of the gain curve when the setup time is the shortest. The system is used to stabilize a radio-frequency-excited waveguide CO2 laser tuned by grating, and the shift of laser frequency is estimated to be less than §25 MHz for an extended period. The system has the advantages of compact structure, small volume, and low cost. It can be applied for frequency stabilization of other kinds of pulsed lasers with adjustable cavity.
140.3518 Lasers, frequency modulated 140.3425 Laser stabilization 140.3470 Lasers, carbon dioxide Chinese Optics Letters
2012, 10(1): 011402
Author Affiliations
Abstract
An injection-locked Ti:sapphire laser is developed, with injection locking achieved using the Pound-Drever-Hall technique. By measuring the dependence of output power on the pump power with various Ti:sapphire laser parameters, we experimentally studied the influences of the ring cavity length, the focal length of the pump-laser mode-matching lens, and the output–coupler transmission on the threshold and slope efficiency. The dependence of the output power on the master laser power is also investigated. The present study provides a guideline for developing a Ti:sapphire laser with high slope efficiency and low threshold.
140.3520 Lasers, injection-locked 140.3425 Laser stabilization 140.3518 Lasers, frequency modulated Chinese Optics Letters
2011, 9(12): 121401
