Active On-Chip Dispersion Control Using a Tunable Silicon Bragg Grating

Abstract

Actively controllable dispersion in on-chip photonic devices is challenging to implement compared with free space optical components where mechanical degrees of freedom can be employed. Here, we present a method by which continuously tunable group delay control is achieved by modulating the refractive index profile of a silicon Bragg grating using thermo-optic effects. A simple thermal heater element is used to create tunable thermal gradients along the grating length, inducing chirped group delay profiles. Both effective blue and red chirp are realised using a single on-chip device over nanometre scale bandwidths. Group delay slopes are continuously tunable over a few ps/nm range from red to blue chirp, compatible with on-chip dispersion compensation for telecommunications picosecond pulse systems.

Design of a Multipurpose Photonic Chip Architecture for THz Dual-Comb Spectrometers

“…There are other solutions to selecting one single line of the comb. One of those solutions is using integrated waveguide Bragg gratings (WBG); however, this implies the use of experimental structures capable of tuning the central wavelength, and to date, there is no building block available on the foundries [40][41][42][43][44] which can be implemented on an MPW, even though they are key components in building high-quality on-chip lasers [28,45]. We can build tunable photonic integrated lasers using WBGs and, with these, we can use the OIL technique or enable optical phase locked loops (OPLLs).…”

Engineering band-edge dynamics of photonic filters via topology optimization

“…By implementing apodization to integrated grating-assisted contra-directional grating waveguides and coupling it with a reflector, it is reported that a two times larger delay is achieved when compared to a device with the same length [14]. Another advantage of BG based delay lines is that, it is also possible to tune the delay characteristic with an active control [15].…”

Editorial for the Special Issue on Silicon Photonics Bloom

“…This Special Issue of Micromachines , entitled “Silicon Photonics Bloom”, has 10 research papers and 2 review articles, covering the scale from material preparation [ 1 , 2 ], to single device design [ 3 , 4 , 5 , 6 , 7 ], to photonic integration [ 8 , 9 , 10 , 11 ], to system architecture [ 12 ]. The demonstrated devices and components include source generation [ 1 , 5 , 6 , 11 ], modulators [ 7 ], switches [ 4 , 8 ], gratings [ 3 , 10 ], and couplers [ 9 , 12 ] and are applied to applications such as dispersion control [ 3 ], photonic memory [ 4 ], optic communication [ 8 , 10 ], polarization management [ 9 ], and photonic computing [ 12 ]. The spectrum of the contributed research spans a wide range, from visible [ 1 , 2 , 6 ], to telecom wavelength [ 3 , 4 , 7 , 8 , 9 , 10 ], to mid-IR [ 11 ], to terahertz frequencies [ 5 ].…”

“…The merits of using Si in integrated photonics come not only from the fabrication compatibility to CMOS technology, but also from its versatility in tuning its optical parameters, which renders itself suitable for active devices. The refractive index of Si can be tuned thermally, as utilized in [ 3 ]; in this study, Klitis et al demonstrate active group delay control in a Si Bragg grating by creating a thermal gradient along the grating length through the metal heaters. By varying the distance between the metal heaters and the waveguides, the thermal gradient profile can be adjusted, which effectively changes the Si refractive index along the grating.…”