A Digital Phase Lock Loop for an External Cavity Diode Laser

Wang, Xiaolong; Tao, Tianjiong; Cheng, Bing; Wu, Bin; Xu, Yuanxin; Wang, Zhaoying; Lin, Qiang

doi:10.1088/0256-307x/28/8/084214

Cited by 13 publications

(4 citation statements)

References 11 publications

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“…Although the frequency mixer has prominent advantages in less residual noise, it lacks robustness and reliability to lock f 0 as a limited capture range. [22] In our scheme, the frequency difference between the divided f 0 and the local reference is compared by a phase-frequency detector (PFD, AD9901). It has a dynamic range from −π to π.…”

Section: Methodsmentioning

confidence: 99%

Pump-induced carrier envelope offset frequency dynamics and stabilization of an Yb-doped fiber frequency comb

Zhao¹,

Li²,

Yang³

et al. 2014

Chinese Phys. B

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In this paper, we demonstrate a carrier envelope phase-stabilized Yb-doped fiber frequency comb seeding by a nonlinear-polarization-evolution (NPE) mode-locked laser at a repetition rate of 60 MHz with a pulse duration of 191 fs. The pump-induced carrier envelope offset frequency ( f 0 ) nonlinear tuning is discussed and further explained by the spectrum shift of the laser pulse. Through the environmental noise suppression, the drift of the free-running f 0 is reduced down to less than 3 MHz within an hour. By feedback control on the pump power with a self-made phase-lock loop (PLL) electronics the carrier envelope offset frequency is well phase-locked with a frequency jitter of 85 mHz within an hour.

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Section: Methodsmentioning

confidence: 99%

Pump-induced carrier envelope offset frequency dynamics and stabilization of an Yb-doped fiber frequency comb

Zhao¹,

Li²,

Yang³

et al. 2014

Chinese Phys. B

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“…The OPLL is closed by forming a feedback circuit. A more detailed design and its performance can be found in our previous work [27].…”

Section: The Principle Of Measurement and Experimental Apparatusmentioning

confidence: 99%

The investigation of a μGal-level cold atom gravimeter for field applications

Wu¹,

Wang²,

Cheng³

et al. 2014

Metrologia

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Typical atomic gravimeters have a heavy magnetic shielding to avoid the quadratic Zeeman effect, and also a complicated active vibration isolation system to suppress the vibration noise. Both of them make it difficult to build a mobile and compact gravimeter. In this paper, we present the implementation of an atomic gravimeter aiming at field applications. Our gravimeter uses improved magnetic coils instead of the expensive mu-metal for magnetic shielding. The quadratic Zeeman shift is evaluated with high accuracy. Moreover, a portable platform of relatively small size is applied for vibration isolation. The total interrogation time is optimized to 120 ms and the repetition rate is 2.2 Hz. A sensitivity of 1.0 × 10−7 g Hz−1/2 and a resolution of 5.7 × 10−9 g within 1000 s integration time are reached. A continuous g measurement over 128 h is carried out. Moreover, a whole seismic wave of about 1 h that occurred in Pakistan on 28 September 2013 is recorded by our atomic gravimeter. The results coincide with that recorded by a traditional seismic detector very well.

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“…OPLL setups involving phase-frequency detectors (PFD) have been presented in Refs. [17] or [18] but for frequency offsets only up to 7 GHz. Both works were concerned with phase coherence requiring complicated loop filters and either field programmable gate array (FPGA) implementation or two parallel proportional-integral (PI) controllers.…”

mentioning

confidence: 99%

Optical frequency locked loop for long-term stabilization of broad-line DFB laser frequency difference

2017

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In multiple applications, phase coherence of the two laser fields locked at a frequency offset is not required [2][3][4][5][6][7][8][9][10][11] and a mere frequency lock is a sufficient solution. Nevertheless, one of the most commonly used solutions is the optical phase locked loop (OPLL) [12][13][14][15]. In a generic OPLL the master laser (ML) and the slave laser (SL) are combined and the beat note is measured on a fast photodiode (PD), compared with a reference value and then the difference is fed through the loop filter and used to tune SL by employing a fast current modulator. However, phase difference has to be kept within tight margins for OPLLs to work, rendering them impractical for broad-line lasers.If the OPLL is constructed to ensure only the frequency drift stabilization and not the phase coherence, it constitutes an optical frequency locked loop (OFLL). Such approach has been presented previously in Ref.[16]; however, it was applied to narrow-line external cavity diodes lasers (ECDL) and was based on a frequency voltage converter, allowing only up to 8 MHz offsets between SL and ML. OPLL setups involving phase-frequency detectors (PFD) have been presented in Refs. [17] or [18] but for frequency offsets only up to 7 GHz. Both works were concerned with phase coherence requiring complicated loop filters and either field programmable gate array (FPGA) implementation or two parallel proportional-integral (PI) controllers. Ivanov et. al. [18] apply their setup to DFB lasers albeit of narrower line (1 MHz) than in our case. They also present a detailed analysis of OPLL performance in the presence of frequency dividers.Here we present an OFLL designed for the stabilization of the long-term (>100 μs) frequency drift. Our setup is based on an integrated PFD chip that compares the beat note signal of ML and SL with low-frequency reference. The PD and PFD are specifically matched to provide the simplicity of setup construction and usage. AbstractWe present an experimental realization of the optical frequency locked loop applied to long-term frequency difference stabilization of broad-line DFB lasers along with a new independent method to characterize relative phase fluctuations of two lasers. The presented design is based on a fast photodiode matched with an integrated phase-frequency detector chip. The locking setup is digitally tunable in real time, insensitive to environmental perturbations and compatible with commercially available laser current control modules. We present a simple model and a quick method to optimize the loop for a given hardware relying exclusively on simple measurements in time domain.Step response of the system as well as phase characteristics closely agree with the theoretical model. Finally, frequency stabilization for offsets within 4-15 GHz working range achieving <0.1 Hz long-term stability of the beat note frequency for 500 s averaging time period is demonstrated. For these measurements we employ an I/Q mixer that allows us to precisely and independently measure the full phase tr...

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A Digital Phase Lock Loop for an External Cavity Diode Laser

Cited by 13 publications

References 11 publications

Pump-induced carrier envelope offset frequency dynamics and stabilization of an Yb-doped fiber frequency comb

Pump-induced carrier envelope offset frequency dynamics and stabilization of an Yb-doped fiber frequency comb

The investigation of a μGal-level cold atom gravimeter for field applications

Optical frequency locked loop for long-term stabilization of broad-line DFB laser frequency difference

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