Widely Tunable Quantum-Dot Source Around 3 μm

We propose a widely tunable parametric source in the 3 μm range, based on intracavity spontaneous parametric down conversion (SPDC) of a quantum-dot (QD) laser emitting at 1.55 μm into signal and idler modes around 3.11 μm. To compensate for material dispersion, we engineer the laser structure to emit in a higher-order transverse mode of the waveguide. The width of the latter is used as a degree of freedom to reach phase matching in narrow, deeply etched ridges, where the in-plane confinement of the QDs avoids non-radiative sidewall electron-hole recombination. Since this design depends critically on the knowledge of the refractive index of In1−xGaxAsyP1−y lattice matched to InP at wavelengths where no data are available in the literature, we have accurately determined them as a function of wavelength (λ = 1.55, 2.12 and 3 μm) and arsenic molar fraction (y = 0.55, 0.7 and 0.72) with a precision of ±4 × 10−3. A pair of dichroic dielectric mirrors on the waveguide facets is shown to result in a continuous-wave optical parametric oscillator (OPO), with a threshold around 60 mW. Emission is tunable over hundreds of nanometers and expected to achieve mW levels

High-Power 810-nm Passively Mode-Locked Laser Diode With Al-Free Active Region

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Optimization of an inductively coupled plasma etching process of GaInP/GaAs based material for photonic band gap applications

International audienceIn this article, we investigate the dry etching of GaInP/GaAs based material system using an inductively coupled plasma(ICP)etching system. In a view to develop a suitable ICP process for the etching of aluminum-free material, ridge waveguides have been fabricated and the effects of the ICP parameters have been assessed. The coil power and the platen power have been varied at constant pressure and temperature for a chlorine-based process. The surface quality, sidewall profile, and selectivity have been reported. We also demonstrate the optimization of the chlorine-based process for deep etching and its subsequent implementation in photonic band gap device fabrication for 1.55μm optical applications. The optimized process has been shown to provide a high aspect ratio and a good selectivity for 250nm diam holes with a depth of 3μm in the GaInP/GaAsmaterial system. The influence of the ICP parameters on this material system have been analyzed mainly by scanning electron microscopy with particular attention drawn to the ways of reducing trenching, an effect commonly associated with ICPetching

Parametric Quantum-dash Source Around 3 µm

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High-Power Tunable Dilute Mode DFB Laser With Low RIN and Narrow Linewidth

International audienceWe have developed a 1-mm-long high-power DFB laser using an asymmetrical cladding based on the dilute waveguide technique. We have obtained about 180 mW output power at 25 °C and >30 mW at 15 °C-85 °C chip temperature with >55-dB sidemode suppression ratio. This temperature range allows a 9.7-nm wavelength tunability. For high output power, the relative intensity noise is lower than −160 dB/Hz in the 0.08-40-GHz frequency range and the optical linewidth is better than 300 kHz

Mid-infrared optical characterization of InGaAsP

International audienceWe present a measurement of the refractive index of In1−xGaxAsyP1−y lattice-matched to InP outside of the rangeavailable in the literature. We have accurately determined the refractive index of In1−xGaxAsyP1−y lattice-matchedto InP as a function of wavelength (λ 1.55, 2.12, and 3 μm) and arsenic molar fraction (y 0.55, 0.7, and0.72). Data is interpolated with a theoretical model and compared to the literature whenever possible. Agreementwith currently available data is good. Uncertainties are estimated, the largest one being related to the samplecomposition. We also measure propagation losses dominated by scattering (0.15–1.2 cm−1) in ridge waveguides,for the same range of compositions at wavelengths of 1.55 μm and 2.12 μm

High Optical Power, High Gain and High Dynamic Range Directly Modulated Optical Link

International audienceIn order to achieve a high output power, high gain and high dynamic range directly modulated optical link, we have developed a high power and low noise DFB laser and a high power handling and high efficiency photodiode with specific designs. The laser exhibits high power (180 mW), high efficiency (0.4 W/A), low RIN and a 7.4 GHz modulation bandwidth. The UTC photodiode offers high efficiency (1 A/W), high saturation current (90 mA) and 15 GHz modulation bandwidth. We have realized a low loss optical link with no amplifier and no impedance matching network. We have obtained a 7.3 GHz modulation bandwidth link with a gain higher than $-7~{hbox {dB}}$. Third order intermodulation of the devices at various different polarization points has been investigated to deduce the optical link dynamic range. At 2.5 GHz, we have demonstrated an OIP3 of 37 dBm and a SFDR close to 120 ${hbox {dB}} cdot {rm Hz}^{2/3}$

Ultrafast response of harmonic modelocked THz lasers

International audienceThe use of fundamental modelocking to generate short terahertz (THz) pulses and THz frequency combs from semiconductor lasers has become a routine affair, using quantum cascade lasers (QCLs) as a gain medium. However, unlike classic laser diodes, no demonstrations of harmonic modelocking, active or passive, have been shown in THz QCLs, where multiple pulses per round trip are generated when the laser is modulated at the harmonics of the cavity's fundamental round-trip frequency. Here, using time-resolved THz techniques, we show for the first time harmonic injection and mode-locking in which THz QCLs are modulated at the harmonics of the round-trip frequency. We demonstrate the generation of the harmonic electrical beatnote within a QCL, its injection locking to an active modulation and its direct translation to harmonic pulse generation using the unique ultrafast nature of our approach. Finally, we show indications of self-starting harmonic emission, i.e., without external modulation, where the QCL operates exclusively on a harmonic (up to its 15th harmonic) of the round-trip frequency. This behaviour is supported by time-resolved simulations of induced gain and loss in the system and shows the importance of the electronic, as well as photonic, nature of QCLs. These results open up the prospect of passive harmonic modelocking and THz pulse generation, as well as the generation of low-noise microwave generation in the hundreds of GHz region