Flattening laser frequency comb spectra with a high dynamic range, broadband spectral shaper on-a-chip

Spectral shaping is critical to many fields of science. In astronomy for example, the detection of exoplanets via the Doppler effect hinges on the ability to calibrate a high resolution spectrograph. Laser frequency combs can be used for this, but the wildly varying intensity across the spectrum can make it impossible to optimally utilize the entire comb, leading to a reduced overall precision of calibration. To circumvent this, astronomical applications of laser frequency combs rely on a bulk optic setup which can flatten the output spectrum before sending it to the spectrograph. Such flatteners require complex and expensive optical elements like spatial light modulators and have non-negligible bench top footprints. Here we present an alternative in the form of an all-photonic spectral shaper that can be used to flatten the spectrum of a laser frequency comb. The device consists of a circuit etched into a silicon nitride wafer that supports an arrayed-waveguide grating to disperse the light over hundreds of nanometers in wavelength, followed by Mach-Zehnder interferometers to control the amplitude of each channel, thermo-optic phase modulators to phase the channels and a second arrayed-waveguide grating to recombine the spectrum. The demonstrator device operates from 1400 to 1800 nm (covering the astronomical H band), with twenty 20 nm wide channels. The device allows for nearly 40 dBs of dynamic modulation of the spectrum via the Mach-Zehnders , which is greater than that offered by most spatial light modulators. With a superluminescent diode, we reduced the static spectral variation to ~3 dB, limited by the properties of the components used in the circuit and on a laser frequency comb we managed to reduce the modulation to 5 dBs, sufficient for astronomical applications.Comment: 15 pages, 10 figures. arXiv admin note: substantial text overlap with arXiv:2209.0945

Four-wave mixing in monolithically integrated multiwavelength lasers manufactured in a generic technology platform

\u3cp\u3eFour-wave mixing (FWM) is reported in a multiwavelength laser chip manufactured in an indium phosphide generic technology platform. Measured conversion efficiencies are presented for frequency spacing of 100, 200, and 1700 GHz. The frequencies correspond to pairs of activated channels modulo the free spectral range of the on-chip integrated arrayed waveguide grating-based laser. Observed FWM trends are similar to reported efficiencies in traveling-wave amplifiers.\u3c/p\u3

Photonic-enabled millimeter-wave F-band wireless link using photonic integrated circuits

Millimeter-waves (30-300 GHz) have interest due to the wide bandwidths available for carrying information, enabling broadband wireless communications. Photonics is a key technology for millimeter wave signal generation, recently demonstrating the use of photonic integration to reduce size and cost. In this paper, we present two dual-wavelength Photonic Integrated Circuit structures designed for signal generation using the optical heterodyne technique. We demonstrate a 1 Gbps data rate wireless link that does not require any stabilization scheme to lock the two wavelengths. Both integrated dual-wavelength sources are based on an Arrayed Waveguide Grating element. A novel building block-Multimode Interference Reflectors - is used to integrate on-chip one of these structures, without need of cleaved facets to define the laser cavity. This fact enables us to locate any of these structures at any location within the photonic chip

F-band millimeter-wave signal generation for wireless link data transmission using on-chip photonic integrated dual-wavelength sources

Millimeter-waves (30-300 GHz) have interest due to the wide bandwidths available for carrying information, enabling broadband wireless communications. Photonics is a key technology for millimeter wave signal generation, recently demonstrating the use of photonic integration to reduce size and cost. In this paper, we present two dual-wavelength Photonic Integrated Circuit (PIC) structures designed for signal generation using the optical heterodyne technique. We demonstrate a 1 Gbps data rate wireless link that does not require any stabilization scheme to lock the two wavelengths. Both integrated dual-wavelength sources are based on an Arrayed Waveguide Grating element. A novel building block-Multimode Interference Reflectors (MIRs) - is used to integrate on-chip one of these structures, without need of cleaved facets to define the laser cavity. This fact enables us to locate any of these structures at any location within the photonic chip

F-band millimeter-wave signal generation for wireless link data transmission using on-chip photonic integrated dual-wavelength sources

\u3cp\u3eMillimeter-waves (30-300 GHz) have interest due to the wide bandwidths available for carrying information, enabling broadband wireless communications. Photonics is a key technology for millimeter wave signal generation, recently demonstrating the use of photonic integration to reduce size and cost. In this paper, we present two dual-wavelength Photonic Integrated Circuit (PIC) structures designed for signal generation using the optical heterodyne technique. We demonstrate a 1 Gbps data rate wireless link that does not require any stabilization scheme to lock the two wavelengths. Both integrated dual-wavelength sources are based on an Arrayed Waveguide Grating element. A novel building block-Multimode Interference Reflectors (MIRs) - is used to integrate on-chip one of these structures, without need of cleaved facets to define the laser cavity. This fact enables us to locate any of these structures at any location within the photonic chip.\u3c/p\u3

Multi-Rate and Multi-Channel Optical Equalizer Based on Photonic Integration

We propose and experimentally demonstrate a photonic integrated circuit (PIC) that operates as an optical equalizer (OE) with multi-rate and multi-channel capability. The OE has the structure of a 3-tap direct form finite impulse response (FIR) filter and is based on the use of micro-ring resonators (MRRs) for the tuning of its delay lines. The PIC is fabricated on TriPleX platform and has 17 reconfigurable elements in total including nine MRRs, five optical couplers and three standalone phase shifters. Using this OE in an on-off keying system with bandwidth limitations we achieve an eye-diagram opening improvement more than 14 dB working with signals at 4.67 and 5.84 Gbaud both in single- and dual-channel operation. Extension to higher modulation formats is direct. Extension to higher symbol rates is also possible via the use of smaller MRRs

Reconfigurable six-section wavelength-tunable distributed bragg reflector laser

\u3cp\u3eA novel operation mode field reconfigurable DBR laser is designed, realized and investigated experimentally. With different controlling of the same hardware, a shared-cavity six-section DBR laser diode can be flexibly configured to operate as a continuous wave or a pulsed wave laser.\u3c/p\u3

Co-Package Technology Platform for Low-Power and Low-Cost Data Centers

[EN] We report recent advances in photonic-electronic integration developed in the European research project L3MATRIX. The aim of the project was to demonstrate the basic building blocks of a co-packaged optical system. Two-dimensional silicon photonics arrays with 64 modulators were fabricated. Novel modulation schemes based on slow light modulation were developed to assist in achieving an efficient performance of the module. Integration of DFB laser sources within each cell in the matrix was demonstrated as well using wafer bonding between the InP and SOI wafers. Improved semiconductor quantum dot MBE growth, characterization and gain stack designs were developed. Packaging of these 2D photonic arrays in a chiplet configuration was demonstrated using a vertical integration approach in which the optical interconnect matrix was flip-chip assembled on top of a CMOS mimic chip with 2D vertical fiber coupling. The optical chiplet was further assembled on a substrate to facilitate integration with the multi-chip module of the co-packaged system with a switch surrounded by several such optical chiplets. We summarize the features of the L3MATRIX co-package technology platform and its holistic toolbox of technologies to address the next generation of computing challenges.The L3MATRIX project is co-funded by the Horizon 2020 Framework Programme of the European Union with Grant Agreement Nr. 688544. L3MATRIX project is an initiative of the Photonics Public Private Partnership.Papatryfonos, K.; Selviah, DR.; Maman, A.; Hasharoni, K.; Brimont, ACJ.; Zanzi, A.; Kraft, J.... (2021). Co-Package Technology Platform for Low-Power and Low-Cost Data Centers. Applied Sciences. 11(13):1-24. https://doi.org/10.3390/app11136098S124111

Co-Package Technology Platform for Low-Power and Low-Cost Data Centers

We report recent advances in photonic–electronic integration developed in the European research project L3MATRIX. The aim of the project was to demonstrate the basic building blocks of a co-packaged optical system. Two-dimensional silicon photonics arrays with 64 modulators were fabricated. Novel modulation schemes based on slow light modulation were developed to assist in achieving an efficient performance of the module. Integration of DFB laser sources within each cell in the matrix was demonstrated as well using wafer bonding between the InP and SOI wafers. Improved semiconductor quantum dot MBE growth, characterization and gain stack designs were developed. Packaging of these 2D photonic arrays in a chiplet configuration was demonstrated using a vertical integration approach in which the optical interconnect matrix was flip-chip assembled on top of a CMOS mimic chip with 2D vertical fiber coupling. The optical chiplet was further assembled on a substrate to facilitate integration with the multi-chip module of the co-packaged system with a switch surrounded by several such optical chiplets. We summarize the features of the L3MATRIX co-package technology platform and its holistic toolbox of technologies to address the next generation of computing challenges

An introduction to InP-based generic integration technology

Photonic integrated circuits (PICs) are considered as the way to make photonic systems or subsystems cheap and ubiquitous. PICs still are several orders of magnitude more expensive than their microelectronic counterparts, which has restricted their application to a few niche markets. Recently, a novel approach in photonic integration is emerging which will reduce the R&D and prototyping costs and the throughput time of PICs by more than an order of magnitude. It will bring the application of PICs that integrate complex and advanced photonic functionality on a single chip within reach for a large number of small and larger companies and initiate a breakthrough in the application of Photonic ICs. The paper explains the concept of generic photonic integration technology using the technology developed by the COBRA research institute of TU Eindhoven as an example, and it describes the current status and prospects of generic InP-based integration technology