SEGA mode locking

Korte pulsen licht worden al sinds lange tijd gebruikt voor een heel scala aan toepassingen, voornamelijk in de fotonica. Zo kun je bijvoorbeeld denken aan materiaalbewerking, datacommunicatie via glasvezel, wetenschappelijk onderzoek, microscopie, eigenlijk teveel om op te noemen. De techniek om korte lichtpulsen te maken, met behulp van een laser, heet “mode locking”. Er is echter een groot probleem bij de standaard methode voor mode locking. De combinatie van een hoge repetitie frequentie (lees: een hoog aantal pulsen per seconde) en een hoog gemiddeld lichtvermogen (in de orde grootte van enkele tientallen Watts) is onmogelijk. Maar omdat fysici er niet van houden als iets “onmogelijk” is, hebben wij een methode ontwikkeld die de combinatie hoge repetitie frequentie en hoog lichtvermogen wel degelijk mogelijk gaat maken. Deze methode noemen wij Separate Gain mode locking, of afgekort SEGA mode locking

Integrated optical beamformers

This paper discusses the challenges towards the realization of the integrated microwave photonic beamformer based on hybrid integration between InP and TriPleX Si3N4/SiO2

Optically switched 56 GBd PAM-4 using a hybrid InP-TriPleX integrated tunable laser based on silicon nitride micro-ring resonators

Tunable lasers are key elements for switching fabrics in future datacenter networks. Experimental results show transmission of 56 GBd PAM-4 data in a switching environment using an integrated silicon nitride micro-ring resonator based tunable laser

CRIT-Alternative narrow-passband waveguide filter for microwave photonic signal processors

This letter presents a novel use of a waveguide circuit consisting of a two-ring resonator-assisted asymmetrical Mach-Zehnder interferometer, which realizes a narrow-passband filter in the context of microwave photonics (MWP). The filter principle is an alternative to the coupled resonator induced transparency and features easy implementation and robust performance. In the experimental demonstration, such a circuit fabricated in SiO2/Si3N4 waveguide technology exhibits a narrow transmission window surrounded by a region of significant suppression. The transmission window features a -3-dB bandwidth of 1 GHz and a -20-dB bandwidth of 3.5 GHz, equivalently a 20-dB roll-off enhancement of three times as compared with a regular add-drop ring resonator. In addition, the investigated waveguide circuit features full reconfigurability based on tunable phase shifters and power couplers. This allows the proposed filter functionality to be combined with other functionalities in a common device, which is of high interest for the realization of flexible on-chip MWP signal processors

25 kHz narrow spectral bandwidth of a wavelength tunable diode laser with a short waveguide-based external cavity

We report on the spectral properties of a diode laser with a tunable external cavity mirror, realized as an integrated optics waveguide circuit. Even though the external cavity is short compared to that of other narrow bandwidth external cavity lasers, the spectral bandwidth of this tunable laser is as small as 25 kHz (FWHM). The side-mode suppression ratio (SMSR) is 50 dB. The laser is able to access preset wavelengths in 200 mu s and can be tuned over the full telecommunications C-band (1530-1565 nm)

High precision wavelength estimation method for integrated optics

A novel and simple approach to optical wavelength measurement is presented in this paper. The working principle is demonstrated using a tunable waveguide micro ring resonator and single photodiode. The initial calibration is done with a set of known wavelengths and resonator tunings. The combined spectral sensitivity function of the resonator and photodiode at each tuning voltage was modeled by a neural network. For determining the unknown wavelengths, the resonator was tuned with a set of heating voltages and the corresponding photodiode signals were collected. The unknown wavelength was estimated, based on the collected photodiode signals, the calibrated neural networks, and an optimization algorithm. The wavelength estimate method provides a high spectral precision of about 8 pm (5&\#x000B7;10&\#x02212;6 at 1550 nm) in the wavelength range between 1549 nm to 1553 nm. A higher precision of 5 pm (3&\#x000B7;10&\#x02212;6) is achieved in the range between 1550.3 nm to 1550.8 nm, which is a factor of five improved compared to a simple lookup of data. The importance of our approach is that it strongly simplifies the optical system and enables optical integration. The approach is also of general importance, because it may be applicable to all wavelength monitoring devices which show an adjustable wavelength response

Q-factor measurements through injection locking of a semiconductor-glass hybrid laser with unknown intracavity losses

The injection locking properties of a newly developed waveguide-based external cavity semiconductor laser have been investigated. Using the injection locking properties to measure the Q-factor of complex optical cavities with unknown internal losses, has been demonstrated for the first time

High precision wavelength estimation method for integrated optics

A novel and simple approach to optical wavelength measurement is presented in this paper. The working principle is demonstrated using a tunable waveguide micro ring resonator and single photodiode. The initial calibration is done with a set of known wavelengths and resonator tunings. The combined spectral sensitivity function of the resonator and photodiode at each tuning voltage was modeled by a neural network. For determining the unknown wavelengths, the resonator was tuned with a set of heating voltages and the corresponding photodiode signals were collected. The unknown wavelength was estimated, based on the collected photodiode signals, the calibrated neural networks, and an optimization algorithm. The wavelength estimate method provides a high spectral precision of about 8 pm (5·10−6 at 1550 nm) in the wavelength range between 1549 nm to 1553 nm. A higher precision of 5 pm (3·10−6) is achieved in the range between 1550.3 nm to 1550.8 nm, which is a factor of five improved compared to a simple lookup of data. The importance of our approach is that it strongly simplifies the optical system and enables optical integration. The approach is also of general importance, because it may be applicable to all wavelength monitoring devices which show an adjustable wavelength response