Rate equation modeling of the frequency noise and the intrinsic spectral linewidth in quantum cascade lasers

Wang, Xing‐Guang; Grillot, Frédéric

doi:10.1364/oe.26.002325

Cited by 25 publications

(14 citation statements)

References 51 publications

(63 reference statements)

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“…Figure 3(a) shows that the FN of the free-running QCL is almost constant at 930 Hz 2 /Hz for low frequencies up to 1.0 GHz. Interestingly, the FN exhibits a broad peak in the frequency range of 10 GHz to 1.0 THz, which is due to the carrier noise perturbation based on our previous analysis [14]. Beyond 10 THz, the FN becomes almost flat at 746 Hz 2 /Hz, which is determined solely by the spontaneous emission noise.…”

Section: Injection Strength Effect On the Fnsupporting

confidence: 51%

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Frequency noise suppression of optical injection-locked quantum cascade lasers

2018

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This work theoretically investigates the frequency noise (FN) characteristics of quantum cascade lasers subject to the optical injection through a set of coupled rate equations with Langevin noise sources. It is shown that the low-frequency FN is completely suppressed by the optical injection, and the suppression bandwidth increases with the increasing injection ratio. The optimal FN peak suppression ratio at an injection ratio of 10 dB reaches 2.9 dB. In addition, it is found that the optical injection at positive frequency detunings close to the locking boundary invokes an additional peak in the FN spectrum, which can be higher than the carrier noise-induced one of free-running lasers. This peak amplitude strongly depends on the value of the linewidth broadening factor. Unlike injection-locked interband lasers, the FN peak does not necessarily exhibit a resonance.

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Section: Injection Strength Effect On the Fnsupporting

confidence: 51%

“…In our recent work, it was demonstrated theoretically that the FN spectrum of free-running QCLs exhibited a broad peak due to the carrier noise induced carrier variation [14]. In this work, we theoretically investigate the FN characteristics of a QCL subject to the optical injection.…”

Section: Introductionmentioning

confidence: 97%

Frequency noise suppression of optical injection-locked quantum cascade lasers

2018

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“…2 shows a schematic of the three-level electronic diagram of the QCLs. Stimulated emission is possible by population inversion between laser levels of 3 and 2 [19].…”

Section: -Theoretical Frameworkmentioning

confidence: 99%

“…The output and dynamic characteristics of the QCL can be described by the following three-level rate equations [19] where the equations can be solved numerically using MATLAB software:…”

Section: -Theoretical Frameworkmentioning

confidence: 99%

“…ΔN = N 3 -N 2 is the population inversion, g 0 is the gain coefficient and S determines the number of cavity photons. τ 32 , τ 31 and τ 21 are the lifetime representing the transition between the corresponding levels, τ out denotes the tunnelling rate, τ sp is the spontaneous emission lifetime, τ p is the photon lifetime, m represents the multiplication factor and β is the spontaneous emission coupling coefficient [19].…”

Section: -Theoretical Frameworkmentioning

confidence: 99%

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Terahertz Plasmonic Quantum Cascade Lasers: a Comprehensive Physics Study

Pakfetrat

Pakarzadeh

2022

Plasmonics

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Generation of terahertz (THz) radiation has been a hot research topic in recent years. Plasmonic quantum cascade lasers (QCLs) are among the most compact and efficient sources to generate THz radiation. In this paper, we comprehensively study plasmonic QCLs designed based on the antenna-feedback structure to generate efficient radiation about the center frequency of 3 THz. By changing the geometric structure of the plasmonic cavity and using two-dimensional simulation, a minimum loss less than 5.9 cm -1 is achieved at the lasing frequency. It is also possible to control the orientation of the output beam either vertically or tilted by changing the geometry of the antenna design via chirped or non-chirped grating scheme. Moreover, the output characteristics of the QCL are simulated based on the three-level rate equations through which the dynamics of the laser, as well as the P-I curve are investigated. Also, the gain spectra for two laser designs (with chirped and non-chirped gratings) are simulated and compared to each other. The results of this paper may provide deep insight into designing efficient laser sources in the THz region.

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Over One Watt Output Power Terahertz Quantum Cascade Lasers by Using High Doping Concentration and Variable Barrier‐Well Height

Lin

Wang

et al. 2022

Physica Rapid Research Ltrs

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A GaAs/AlGaAs‐based terahertz quantum cascade laser with a peak power of 1.31 W and average power of 52 mW is demonstrated. To realize a high output power, an effective way is to increase the electron density at the active region by using a high doping level. This work aims to optimize a design enabling to use a heavy doping level, by realigning the resonant tunneling which can be seriously degraded due to a band bending from this heavy local doping. With variable quantum well and barrier height, the design owns an improved parameter tuning freedoms, and a saturation of peak gain can be achieved at a relatively high doping concentration of 1.0 × 1017 cm−3, which is twice higher than the recently reported device. Nonequilibrium Green's function method including full carriers scattering effect is used to carry out the design optimization, mainly including the realignment of resonant tunneling and suppression of leakages via high‐energy confined levels. In the experiment, a 14 μm thick active layer for this design is grown and also large mesa size is developed. To ensure a quasi‐continuous wave (quasi‐CW) operation, the heat dissipation is also managed.

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Rate equation modeling of the frequency noise and the intrinsic spectral linewidth in quantum cascade lasers

Cited by 25 publications

References 51 publications

Frequency noise suppression of optical injection-locked quantum cascade lasers

Frequency noise suppression of optical injection-locked quantum cascade lasers

Terahertz Plasmonic Quantum Cascade Lasers: a Comprehensive Physics Study

Over One Watt Output Power Terahertz Quantum Cascade Lasers by Using High Doping Concentration and Variable Barrier‐Well Height

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