Frequency stability of a dual wavelength quantum cascade laser

Abstract

Abstract:We characterized the dual wavelength operation of a distributed Bragg reflector (DBR) quantum cascade laser (QCL) operating at 4.5 μm using two independent optical frequency discriminators. The QCL emits up to 150 mW fairly evenly distributed between two adjacent Fabry-Perot modes separated by ≈11.6 GHz. We show a strong correlation between the instantaneous optical frequencies of the two lasing modes, characterized by a Pearson correlation coefficient of 0.96. As a result, we stabilized one laser mode of the QCL to a N 2 O transition using a side-of-fringe locking technique, reducing its linewidth by a factor 6.2, from 406 kHz in free-running operation down to 65 kHz (at 1-ms observation time), and observed a simultaneous reduction of the frequency fluctuations of the second mode by a similar amount, resulting in a linewidth narrowing by a factor 5.4, from 380 kHz to 70 kHz. This proof-ofprinciple demonstration was performed with a standard DBR QCL that was not deliberately designed for dual-mode operation. These promising results open the door to the fabrication of more flexible dual-mode QCLs with the use of specifically designed gratings in the future.

High-Power, Narrow-Linewidth Distributed-Feedback Quantum-Cascade Laser for Molecular Spectroscopy

“…The measured device shows a twice higher output power than the most powerful narrow-linewidth dual-mode QCL reported so far to our knowledge [32] (see Figure 5 and Table 1). Figure 5 shows the output power of the devices reported in the literature in Table 1 as a function of the ratio between the FWHM and the emitted frequency of the device enabling a direct comparison of the linewidth across different emission wavelength ranges.…”

Квантово-Каскадные Лазеры С Распределенным Брэгговским Отражателем, Сформированным Методом Ионно-Лучевого Травления

“…Как следствие, в спектре генерации возникают дополнительные моды, что снижает процент выхода годных приборов [10]. Использование распределенных брэгговских отражателей (РБО) [11][12][13][14] исключает эффект пространственного выжигания дыр ( " spatial hole burning"), наблюдаемый в длинных РОС-лазерах. Ранее одночастотный режим генерации в ККЛ с РБО был реализован в спектральном диапазоне 4.5−5.0 µm [11,13].…”

Mid-IR Faraday optical filter with an ultra-narrow single transmission peak at 5.33 μm

“…This mid-infrared filter with an ultra-narrow bandwidth presented here potentially offers a novel and effective filtering method for QCL-based applications. [9][10][11][12] Gas-phase NO is selected as the working material of the MIFOF because NO is the typical representative of paramagnetic molecules. Its fundamental vibrational band located in the 5.3 μm wavelength region has the strongest line-intensity and is therefore promising for good filter performance.…”