Abstract:The spectral dependence of the linewidth enhancement factor ( αH-factor) of a multimode InAs/GaAs quantum dot laser is analyzed. Amplified spontaneous and high-frequency modulation methods are used to experimentally retrieve the αH-factor of each longitudinal mode below and above the threshold. A dispersion of the αH-factor is unlocked across the entire optical spectrum, which is further illustrated in the context of four wave mixing experiments. The results show that the induced conversion efficiency is incre… Show more
“…Since the modes are locked to each other, one can expect the same width of each line within the mode-locked spectrum. The slightly increased linewidth for the longer lasing wavelength may be attributed to the dispersion of the α H factor across the lasing spectrum 35 . Figure 6 Linewidth measurement of two different free-running 25G COMB modes at 28 °C (without thermal stabilization); gain and absorber section are driven from batteries with 200 mA and 1.5 V, respectively; dots show measured data, solid lines represent corresponding Voigt fits.…”
We report a continuous-wave, O-band quantum-dot semiconductor comb laser for WDM optical interconnects exhibiting a 2.2 THz optical bandwidth with up to 89 comb wavelengths spaced at 25 GHz, over 30% peak ex-facet electrical-to-optical power conversion efficiency, up to 270 mW of usable laser power, relative intensity noise below − 135 dB/Hz per individual mode, individual laser mode linewidth of 140 kHz, mode beating linewidths of 50 kHz across all modes, and stable far-field output with 75% coupling efficiency to PM fiber in a butterfly package.
“…Since the modes are locked to each other, one can expect the same width of each line within the mode-locked spectrum. The slightly increased linewidth for the longer lasing wavelength may be attributed to the dispersion of the α H factor across the lasing spectrum 35 . Figure 6 Linewidth measurement of two different free-running 25G COMB modes at 28 °C (without thermal stabilization); gain and absorber section are driven from batteries with 200 mA and 1.5 V, respectively; dots show measured data, solid lines represent corresponding Voigt fits.…”
We report a continuous-wave, O-band quantum-dot semiconductor comb laser for WDM optical interconnects exhibiting a 2.2 THz optical bandwidth with up to 89 comb wavelengths spaced at 25 GHz, over 30% peak ex-facet electrical-to-optical power conversion efficiency, up to 270 mW of usable laser power, relative intensity noise below − 135 dB/Hz per individual mode, individual laser mode linewidth of 140 kHz, mode beating linewidths of 50 kHz across all modes, and stable far-field output with 75% coupling efficiency to PM fiber in a butterfly package.
“…11 To obtain the α H -factor above the threshold, other measurement methods, such as optical injection or optical phase modulation can be considered. 12,13 Therefore, the above-threshold α H of a single mode laser can be extracted from the optical injection-locking boundaries whereas the optical phase modulation can provide a comprehensive analysis of the α H -factor across the the entire optical spectrum of a multimodes laser. But, it is important to stress that these two methods cannot release any other additional information about the DFB laser.…”
Distributed feedback lasers are key ingredients of high-speed, high-capacity integrated photonic chips. In this work, we extract the linewidth enhancement factor above threshold by measuring the transitional points in the optical-injection stability map from a quantum well distributed feedback laser with a temperature-controlled mismatch between the lasing and optical gain peaks. This unique measurement technique allows the simultaneous extraction of important parameters influencing the linewidth, particularly the photon lifetime. When the current is higher than twice threshold and 50 ℃, the linewidth enhancement factor is smaller than that at 10 ℃. This effect is attributed to the increasing differential gain at the lasing peak position, which is a result of the larger optical mismatch. We also measured the spectral linewidth at different temperatures, which then yields the spontaneous emission factor, n sp . Due to the low linewidth enhancement factor at high temperatures, a large photon lifetime, and a modest increase in n sp , the linewidth does not drastically increase with pump current and stays below 100 kHz at 50 ℃. Overall, the stability of the linewidth enhancement factor combined with the large optical mismatch brings a relative temperature insensitivity, which is of paramount importance for applications requiring high-temperature operation and improved coherent light.
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