Comb-based WDM transmission at 10 Tbit/s using a DC-driven quantum-dash mode-locked laser diode

Chip-scale frequency comb generators have the potential to become key building blocks of compact wavelength-division multiplexing (WDM) transceivers in future metropolitan or campus-area networks. Among the various comb generator concepts, quantum-dash (QD) mode-locked laser diodes (MLLD) stand out as a particularly promising option, combining small footprint with simple operation by a DC current and offering flat broadband comb spectra. However, the data transmission performance achieved with QD-MLLD was so far limited by strong phase noise of the individual comb tones, restricting experiments to rather simple modulation formats such as quadrature phase shift keying (QPSK) or requiring hard-ware-based compensation schemes. Here we demonstrate that these limitations can be over-come by digital symbol-wise phase tracking algorithms, avoiding any hardware-based phase-noise compensation. We demonstrate 16QAM dual-polarization WDM transmission on 38 channels at an aggregate net data rate of 10.68 Tbit/s over 75 km of standard single-mode fiber. To the best of our knowledge, this corresponds to the highest data rate achieved through a DC-driven chip-scale comb generator without any hardware-based phase-noise reduction schemes

Semiconductor laser mode locking stabilization with optical feedback from a silicon PIC

Semiconductor mode-locked lasers can be used in a variety of applications ranging from multi-carrier sources for WDM communication systems to time base references for metrology. Their packaging in compact chip- or module-level systems remains however burdened by their strong sensitivity to back-reflections, quickly destroying the coherence of the mode-locking. Here, we investigate the stabilization of mode-locked lasers directly edge coupled to a silicon photonic integrated circuit, with the objective of moving isolators downstream to the output of the photonic circuit. A 2.77 kHz 3 dB RF linewidth, substantially improved compared to the 15.01 kHz of the free running laser, is obtained in the best case. Even in presence of detrimental reflections from the photonic circuit, substantial linewidth reductions from 20 kHz to 8.82 kHz, from 572 kHz to 14.8 kHz, and from 1.5 MHz to 40 kHz are realized

Terahertz-bandwidth coherence measurements of a quantum dash laser in passive and active mode-locking operation

International audienceThis research carries out coherence measurements of a 42.7GHz quantum dash (QDash) semiconductor laser when passively, electrically and optically mode-locked. Coherence of the spectral lines from the mode-locked laser is determined by examining the radio frequency (RF) beat-tone linewidth as the mode spacing is increased up to 1.1THz. Electric field measurement of the QDash laser are also presented, from which a comparison between experimental results and accepted theory for coherence in passively mode-locked lasers has been performed

Quantum dash based directly modulated lasers for long-reach access networks

International audienceWe demonstrate an innovative 10 Gbps single mode optical transmitter with the capacity of error free transmission in the range of 0 to 100kms with constant biasing conditions using a Quantum Dash Directly Modulated Laser. We use a commercially available etalon filter as passive optical filter to achieve penalty free transmission with a dynamic extinction ratio (DER) > 6dB over a large range of fiber spans

Ultra-fast optical ranging using quantum-dash mode-locked laser diodes

Laser-based light detection and ranging (LiDAR) is key to many applications in science and industry. For many use cases, compactness and power efficiency are key, especially in high-volume applications such as industrial sensing, navigation of autonomous objects, or digitization of 3D scenes using hand-held devices. In this context, comb-based ranging systems are of particular interest, combining high accuracy with high measurement speed. However, the technical complexity of miniaturized comb sources is still prohibitive for many applications, in particular when high optical output powers and high efficiency are required. Here we show that quantum-dash mode-locked laser diodes (QD-MLLD) offer a particularly attractive route towards high-performance chip-scale ranging systems. QD-MLLDs are compact, can be easily operated by a simple DC drive current, and provide spectrally flat frequency combs with bandwidths in excess of 2 THz, thus lending themselves to coherent dual-comb ranging. In our experiments, we show measurement rates of up to 500 MHz—the highest rate demonstrated with any ranging system so far. We attain reliable measurement results with optical return powers of only – 40 dBm, corresponding to a total loss of 49 dB in the ranging path, which corresponds to the highest loss tolerance demonstrated so far for dual-comb ranging with chip-scale comb sources. Combing QD-MLLDs with advanced silicon photonic receivers offers an attractive route towards robust and technically simple chip-scale LiDAR systems

Single quantum dash mode-locked laser as a comb-generator in four-channel 112 Gbit/s WDM transmission

International audienceWe demonstrate 100 km transmission at 28 Gbit/s/channel of 4 DWDM channels using a single quantum-dash mode-locked laser. The amplitude noise of each filtered laser line is improved using limiting amplification in an SOA

Datação por traços de fissão e geocronologia do Plio-Quaternário

A datação por traços de fissão aplicada em estudos do Plio-Quaternário é pouco conhecida no Brasil. O objetivo principal do presente manuscrito, redigido em língua portuguesa, é apresentar e fazer ampla divulgação das potencialidades desta metodologia aos pesquisadores que atuam nesse domínio temporal das ciências da natureza no nosso país. Para tal são apresentados detalhadamente todos os aspectos da datação por Traços de Fissão. São abordados os princípios básicos da datação por Traços de Fissão, a equação da idade, precisão e acurácia, as técnicas analíticas utilizadas em função das particularidades e natureza dos materiais, suas limitações assim como os casos de sucesso. Também são apresentados diversos estudos de caso com exemplos de utilização da metodologia nas variadas áreas de aplicação de pesquisas do Plio-Quaternário, inclusive em arqueologia