Active Stabilization of Terahertz Semiconductor Dual‐Comb Laser Sources Employing a Phase Locking Technique

Zhao, Yiran; Li, Ziping; Zhou, Kang; Liao, Xiaoyu; Guan, Wanchun; Wan, Wen‐Ming; Yang, Sijia; Cao, Juncheng; Dong, Xu; Barbieri, Stefano; Li, Hua

doi:10.1002/lpor.202000498

Cited by 25 publications

(23 citation statements)

References 44 publications

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“…The Allan deviation is a classic statical method that has been widely used to evaluate the stability of a signal with time. For the frequency or amplitude Allan deviations, we first recorded frequency or amplitude values as a function of time, and then a formula [34,35] was used to mathematically calculate the Allan deviation plots. Overall, compared to the type A cold finger, the type B cold finger brings about improvements in the phase noise and Allan deviations.…”

Section: Resultsmentioning

confidence: 99%

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Improved comb and dual-comb operation of terahertz quantum cascade lasers utilizing a symmetric thermal dissipation

Wang,

Li,

Liao

et al. 2021

Preprint

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In the terahertz frequency range, the quantum cascade laser (QCL) is a suitable platform for the frequency comb and dual-comb operation. Improved comb performances have been always much in demand. In this work, by employing a symmetric thermal dissipation scheme, we report an improved frequency comb and dual-comb operation of terahertz QCLs. Two configurations of cold fingers, i.e., type A and B with asymmetric and symmetric thermal dissipation schemes, respectively, are investigated here. A finite-element thermal analysis is carried out to study the parametric effects on the thermal management of the terahertz QCL. The modeling reveals that the symmetric thermal dissipation (type B) results in a more uniform thermal conduction and lower maximum temperature in the active region of the laser, compared to the traditional asymmetric thermal dissipation scheme (type A). To verify the simulation, experiments are further performed by measuring laser performance and comb characteristics of terahertz QCLs emitting around 4.2 THz mounted on type A and type B cold fingers. The experimental results show that the symmetric thermal dissipation approach (type B) is effective for improving the comb and dual-comb operation of terahertz QCLs, which can be further widely adopted for spectroscopy, imaging, and near-field applications.

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Section: Resultsmentioning

confidence: 99%

“…spectrum analyser [13,35]. The frequency difference between 𝑓 BN1 and 𝑓 BN2 , i.e., 40.0 MHz for type A cold finger and 36.6 MHz for type B cold finger, determines the line spacing of the down-converted dual-comb spectra.…”

Section: Resultsmentioning

confidence: 99%

Improved comb and dual-comb operation of terahertz quantum cascade lasers utilizing a symmetric thermal dissipation

Wang,

Li,

Liao

et al. 2021

Preprint

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“…This means that it is more feasible to lock the dualcomb carrier offset frequency (f ceo,dc =f ceo1 -f ceo2 ) and the dual-comb repetition frequency (f rep,dc =f rep1 -f rep2 ) because the entire dual-comb signal can be precisely obtained through the multiheterodyne beating. Recently, we have achieved the active stabilization of a THz QCL dual-comb source by phase locking one dual-comb line to a microwave local oscillator employing a traditional phase-locked loop [31]. Although the stability of the dual-comb lines was improved, we observed that the noise of the dual-comb lines that were located far away from the locked line (carrier) increased with the increase of the frequency difference.…”

Section: Introductionmentioning

confidence: 99%

Self-Referenced Terahertz Semiconductor Dual-Comb Sources

Li¹,

Ma²,

Zhang³

et al. 2022

Preprint

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Employing two frequency combs with a slight difference in repetition frequencies, the dual-comb source shows unique advantages in high precision spectroscopy, imaging, ranging, communications, etc. In the terahertz (THz) frequency range, the electrically pumped quantum cascade laser (QCL) offers the possibility of realizing the compact dualcomb source due to its semiconductor-based chip-scale configuration. Although the active stabilization of a THz QCL dual-comb source was demonstrated by phase locking one of the dual-comb lines, the full stabilization of all dual-comb lines is still challenging. Here, we propose a self-reference method to obtain a fully stabilized dual-comb signal on a pure THz QCL platform. Without using any external locking components, we filter out one dual-comb line and beat it with the whole dual-comb signal, which eliminates the common carrier offset frequency noise and reduces the dual-comb repetition frequency noise. It is experimentally demonstrated that the self-reference technique can significantly improve the long-term stability of the dual-comb signal. A record of the "maxhold" linewidth of 14.8 kHz (60 s time duration) is obtained by implementing the self-reference technique, while without the selfreference the dual-comb lines show a "maxhold" linewidth of 2 MHz (15 s time duration). The method provides the simplest way to improve the long-term stability of THz QCL dual-comb sources, which can be further adopted for high precision measurements.

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“…[4] Though the sources and detectors develop very quickly, but the tunable functional components are still lag behind because of the difficult of convenient manipulation. [5][6][7][8] To the further practical applications, there is an urgent requirement to the functional devices with fine DOI: 10.1002/andp.202100355 performances. Surface plasmons (SPs) are 2D electro-magnetic waves confined at a metal-dielectric interface, exhibiting subwavelength confinement of electric field in the direction normal to a conductor-dielectric interface.…”

Section: Introductionmentioning

confidence: 99%

3D Dirac Semimetal Supported Tunable TE Modes

Liu

Shi

2022

Annalen der Physik

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The tunable propagation properties of transverse electric (TE) plasmonic modes have been investigated in the mid-IR spectral region by using air-Dirac semimetal (DSM)-Si asymmetric structures, including the effects of Fermi levels, temperatures, and scattering times. The results manifest that on the condition that the Fermi level of DSM layer is not very large (2|𝝁 c |<ℏ𝝎) and temperature is relatively high (about 100 K), the proposed DSM asymmetric structure supports obvious TE modes, which is quite different from the graphene symmetric structure limited to low liquid helium temperature. The transition frequency increases with Fermi level, the peak position of the real part and the saturation region of the imaginary part of effective index indicates an obvious blue shift. As temperature decreases, the contribution of interband transition becomes stronger, the 3D DSM indicates better dielectric properties and sustains stable TE mode. If scattering time is shorter than 0.1 ps, its effects on the propagation properties are very strong, resulting in a redshift of the real part of effective index. The results are very helpful to understand the tunable properties of DSM TE structures and aid the design of novel plasmonic devices, such as polarizers, modulators, and filters.

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Active Stabilization of Terahertz Semiconductor Dual‐Comb Laser Sources Employing a Phase Locking Technique

Cited by 25 publications

References 44 publications

Improved comb and dual-comb operation of terahertz quantum cascade lasers utilizing a symmetric thermal dissipation

Improved comb and dual-comb operation of terahertz quantum cascade lasers utilizing a symmetric thermal dissipation

Self-Referenced Terahertz Semiconductor Dual-Comb Sources

3D Dirac Semimetal Supported Tunable TE Modes

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