Roberto Morandotti

A Radio Frequency Channelizer based on Cascaded Integrated Micro-ring Resonator Optical Comb Sources and Filters

We report a broadband RF channelizer based on an integrated optical frequency Kerr micro-comb source, with an RF channelizing bandwidth of 90 GHz, a high RF spectral slice resolution of 1.04 GHz, and experimentally verify the RF performance up to 19 GHz. This approach to realizing RF channelizers offers reduced complexity, size, and potential cost for a wide range of applications to microwave signal detection.

High-order Radio Frequency Differentiation via Photonic Signal Processing with an Integrated Micro-resonator Kerr Optical Frequency Comb Source

We demonstrate the use of integrated micro-resonator based optical frequency comb sources as the basis for transversal filtering functions for microwave and radio frequency photonic filtering and advanced functions. Keywords—frequency comb, microwave, micro-resonator

Integrated Kerr comb-based reconfigurable transversal differentiator for microwave photonic signal processing

An arbitrary-order intensity differentiator for high-order microwave signal differentiation is proposed and experimentally demonstrated on a versatile transversal microwave photonic signal processing platform based on integrated Kerr combs. With a CMOS-compatible nonlinear micro-ring resonator, high quality Kerr combs with broad bandwidth and large frequency spacings are generated, enabling a larger number of taps and an increased Nyquist zone. By programming and shaping individual comb lines’ power, calculated tap weights are realized, thus achieving a versatile microwave photonic signal processing platform. Arbitrary-order intensity differentiation is demonstrated on the platform. The RF responses are experimentally characterized, and systems demonstrations for Gaussian input signals are also performed.

Optical square waves from a nonlinear amplifying loop mirror laser (Conference Presentation)

Optical square wave sources are particularly important for applications inxa0high speedxa0signal processing and optical communications. In most realizations, optical square waves are generated by electro-optic modulation,xa0dispersion engineering of mode-locked lasers,xa0polarizationxa0switching, or by exploiting opticalxa0bi-stabilityxa0and/or optical delayed feedback in semiconductor diode lasers, as well asxa0vertical-cavityxa0surface-emitting lasers (VCSELs). All such configurations are bulky andxa0cause significant timing jitters.xa0Here we demonstratexa0the direct generation of optical square waves from a polarization-maintaining figure-eight nonlinear amplifying loop mirror (NALM) configuration that uses an embedded high index glass micro-cavity as the nonlinear element.xa0Suchxa0a NALMxa0mimics the behavior of a saturable absorber and has been used to reach passivexa0mode-lockingxa0of pico- and even nano-second pulses.xa0In our method, the NALM, including a high-Qxa0micro-ringxa0resonator,xa0acts as an ultra-narrowband spectral filter and at the same time provides a large nonlinear phase-shift. Previously we have demonstratedxa0that such a configuration enables sufficient nonlinear phase-shifts for low-power narrow-bandwidth (~100 MHz FWHM) passive mode-locked laser operation.xa0Here we demonstrate the switching of stable optical square wave pulses from conventional mode-locked pulses by adjusting thexa0cavity properties.xa0In addition, the square wave signal characteristics, such as repetition rate andxa0pulse duration, can be also modified in a similar fashion. The source typically produces nanosecond optical square wave pulses with a repetition ratexa0of ~ 120 MHz atxa01550nm. In order to verify the reach of our approach, we compare our experimental results with numerical simulations using a delay differential equation model tailored for a figure-eight laser.

Integrated Kerr Comb-based Reconfigurable Transversal Differentiator for Microwave Photonic Signal Processing

An integrated reconfigurable transversal differentiator is achieved based on a microring resonator. The RF responses of different orders of differentiation are experimentally characterized. Systems demonstrations for Gaussian pulses are performed.

Optical intensity square root differentiator based on an integrated Kerr frequency comb source

We propose and experimentally demonstrate an optical intensity square root differentiator based on an integrated comb source. The proposed differentiator features full reconfigurablity and compact structure. Transmission responses and temporal characterization are also experimentally demonstrated.

Efficient Wavelength Conversion and Net Parametric Gain via Fwm in a High Index Doped Silica Waveguide

We demonstrate C-band subpicosecond wavelength conversion over > 100nm, exploiting four wave mixing in a high index doped silica waveguide spiral of 45cm, showing a +16.5dB net gain for a 40W peak pump power.

Enhancement of Third Harmonic Generation in Nonlocal Solitons

We report on the observation of type I third harmonic generation enhanced by tight localization of fs laser light in nonlocal spatial solitons excited in nematic liquid crystals.