Bandwidth and conversion-efficiency analysis of Kerr soliton combs in dual-pumped resonators with anomalous dispersion

Kerr frequency combs generated in high-Q microresonators offer an immense potential in many applications, and predicting and quantifying their behavior, performance and stability is key to systematic device design. Based on an extension of the Lugiato-Lefever equation we investigate in this paper the perspectives of changing the pump scheme from the well-understood monochromatic pump to a dual-tone configuration simultaneously pumping two modes. For the case of anomalous dispersion we give a detailed study of the optimal choices of detuning offsets and division of total pump power between the two modes in order to optimize single-soliton comb states with respect to performance metrics like power conversion efficiency and bandwidth. Our approach allows also to quantify the performance metrics of the optimal single-soliton comb states and determine their trends over a wide range of technically relevant parameters

Slice-Less Optical Arbitrary Waveform Measurement (OAWM) in a Bandwidth of More than 600 GHz Using Soliton Microcombs

We propose and demonstrate a novel scheme for optical arbitrary waveform measurement (OAWM) that exploits chip-scale Kerr soliton combs as highly scalable multiwavelength local oscillators (LO) for ultra-broadband full-field waveform acquisition. In contrast to earlier concepts, our approach does not require any optical slicing filters and thus lends itself to efficient implementation on state-of-the-art high-index-contrast integration platforms such as silicon photonics. The scheme allows to measure truly arbitrary waveforms with high accuracy, based on a dedicated system model which is calibrated by means of a femtosecond laser with known pulse shape. We demonstrated the viability of the approach in a proof-of-concept experiment by capturing an optical waveform that contains multiple 16 QAM and 64 QAM wavelength-division multiplexed (WDM) data signals with symbol rates of up to 80 GBd, reaching overall line rates of up to 1.92 Tbit/s within an optical acquisition bandwidth of 610 GHz. To the best of our knowledge, this is the highest bandwidth that has so far been demonstrated in an OAWM experiment

Sub-kHz-linewidth external-cavity laser (ECL) with Si3_3N4_4 resonator used as a tunable pump for a Kerr frequency comb

Combining optical gain in direct-bandgap III-V materials with tunable optical feedback offered by advanced photonic integrated circuits is key to chip-scale external-cavity lasers (ECL), offering wideband tunability along with low optical linewidths. External feedback circuits can be efficiently implemented using low-loss silicon nitride (Si$_3$ N$_4$) waveguides, which do not suffer from two-photon absorption and can thus handle much higher power levels than conventional silicon photonics. However, co-integrating III-V-based gain elements with tunable external feedback circuits in chip-scale modules still represents a challenge, requiring either technologically demanding heterogeneous integration techniques or costly high-precision multi-chip assembly, often based on active alignment. In this work, we demonstrate Si$_3$N$_4$-based hybrid integrated ECL that exploit 3D-printed structures such as intra-cavity photonic wire bonds and facet-attached microlenses for low-loss optical coupling with relaxed alignment tolerances, thereby overcoming the need for active alignment while maintaining the full flexibility of multi-chip integration techniques. In a proof-of-concept experiment, we demonstrate an ECL offering a 90 nm tuning range (1480 nm–1570 nm) with on-chip output powers above 12 dBm and side-mode suppression ratios of up to 59 dB in the center of the tuning range. We achieve an intrinsic linewidth of 979 Hz, which is among the lowest values reported for comparable feedback architectures. The optical loss of the intra-cavity photonic wire bond between the III-V gain element and the Si$_3$N$_4$-based tunable feedback circuit amounts to approximately (1.6 ± 0.2) dB. We use the ECL as a tunable pump laser to generate a dissipative Kerr soliton frequency comb. To the best of our knowledge, our experiments represent the first demonstration of a single-soliton Kerr comb generated with a pump that is derived from a hybrid ECL

Hybrid external-cavity lasers (ECL) using photonic wire bonds as coupling elements

Combining semiconductor optical amplifiers (SOA) on direct-bandgap III–V substrates with low-loss silicon or silicon-nitride photonic integrated circuits (PIC) has been key to chip-scale external-cavity lasers (ECL) that offer wideband tunability along with small optical linewidths. However, fabrication of such devices still relies on technologically demanding monolithic integration of heterogeneous material systems or requires costly high-precision package-level assembly, often based on active alignment, to achieve low-loss coupling between the SOA and the external feedback circuits. In this paper, we demonstrate a novel class of hybrid ECL that overcome these limitations by exploiting 3D-printed photonic wire bonds as intra-cavity coupling elements. Photonic wire bonds can be written in-situ in a fully automated process with shapes adapted to the mode-field sizes and the positions of the chips at both ends, thereby providing low-loss coupling even in presence of limited placement accuracy. In a proof-of-concept experiment, we use an InP-based reflective SOA (RSOA) along with a silicon photonic external feedback circuit and demonstrate a single-mode tuning range from 1515 to 1565 nm along with side mode suppression ratios above 40 dB and intrinsic linewidths down to 105 kHz. Our approach combines the scalability advantages of monolithic integration with the performance and flexibility of hybrid multi-chip assemblies and may thus open a path towards integrated ECL on a wide variety of integration platforms

Low Noise and Wideband Optical Frequency Comb Generation Based on an Optoelectronic Oscillator

We propose a scheme to generate wideband optical frequency comb and low phase noise microwave signal simultaneously by incorporating an optical frequency comb generator in an optoelectronic oscillator. 12.5 and 25 GHz combs are generated and phase noise are investigated. ? OSA 2013.EI

Widely Tunable Dual-loop Optoelectronic Oscillator

We demonstrate a record widely tunable dual-loop optoelectronic oscillator with tunable band from 3.39 to 57.50 GHz. The single-side band phase noise is below -120 dBc/Hz at 10 kHz offset for all the measurement frequency points. ? 2014 OSA.EI

Tunable DC-60 GHz RF generation based on a dual loop Brillouin optoelectronic oscillator

Tunable RF generation from DC to 60 GHz based on dual loop Brillouin Optoelectronic oscillator is experimentally demonstrated. Frequency and power stability is improved compared with single loop.EI

50 GHz optical frequncy Comb generation based on an optoelectronic oscillator

50 GHz repetition rate optical frequency comb with very low phase noise is experimentally demonstrated by incorporating an optical frequency comb generator (OFCG) in an optoelectronic oscillator (OEO). To the best of our knowledge, this is the highest repetition rate optical frequency comb ever achieved by an OFCG. What more important is that, the OFCG is driven by the 50 GHz millimeter-wave signal oscillating in the OEO, and no frequency synthesizer is needed. The single-sideband (SSB) phase noise of the 50 GHz signal oscillating in the OEO is theoretically analyzed by the Leeson formula. The calculation result shows that the SSB phase noise could be as low as -125 dBc/Hz at 10 kHz offset with our experimental parameters.http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000346295600084&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=8e1609b174ce4e31116a60747a720701Engineering, Electrical & ElectronicPhysics, AppliedTelecommunicationsEICPCI-S(ISTP)

Widely Tunable Dual Loop Optoelectronic Oscillator based on a Single-Bandpass Microwave Photonic Filter and a Recirculating Delay Line

A wideband tunable dual loop Optoelectronic Oscillator based on a single-bandpass microwave photonic filter and a recirculating delay line is proposed and experimentally demonstrated. A tunable frequency range from 10.23 to 26.69 GHz is obtained. ? OSA 2014.EI