Dynamic Wavelength Conversion Research Articles

Reconfigurable magnon interference by on-chip dynamic wavelength conversion

Spin waves (SWs), an ultra-low power magnetic excitation in ferro or antiferromagnetic media, have tremendous potential as transport less data carriers for post-CMOS technology using their wave interference properties. The concept of magnon interference originates from optical interference, resulting in a historical taboo of maintaining an identical wavevector for magnon interference-based devices. This makes the attainment of on-chip design reconfigurability challenging owing to the difficulty in phase tuning via external fields. Breaking the taboo, this study explores a novel technique to systematically control magnon interference using asymmetric wavevectors from two different SW modes (magnetostatic surface SWs and backward volume magnetostatic SWs) in a microstructured yttrium iron garnet crossbar. Using this system, we demonstrate phase reconfigurability in the interference pattern by modulating the thermal landscape, modifying the dispersion of the interfering SW modes. Thus, we manifest that such a tunable interference can be used to implement reconfigurable logic gates operating between the XNOR and XOR modes by using symmetric and asymmetric interference, respectively.

Investigation of the dynamic features of a moveable ultrahigh-Q nanocavity

Although the approach of forming an ultrahigh-Q nanocavity via local refractive index tuning in a PC waveguide was proposed a decade ago, it has not yet been employed to realize a moveable ultrahigh-Q nanocavity, thereby the dynamic physics related to a moving resonator remain unknown. Here we demonstrate that a dynamically-formed cavity is essentially moveable, so that we can use this nanocavity to trap, store, and transfer signal photons, enabling free photon control. For a high cavity moving speed, we find the trapped signal energy will radiate out of the moving cavity. We think this interesting phenomenon originates from Doppler-effect-induced resonant frequency split in a moving resonator and the accompanied change of energy capacity. In addition, we present an analytical model to reveal why and how the trapping and storing processes are accompanied by significant spectral bandwidth compression and dynamic wavelength conversion, which are critical for achieving dynamic ultrahigh-Q nanocavity. This approach may find application in photon memories, quantum computing, and controllable light-matter interactions.

Dynamic Wavelength Conversion in Copropagating Slow-Light Pulses

Dynamic wavelength conversion (DWC) is obtained by controlling copropagating slow-light signal and control pulse trajectories. Our method is based on the understanding that conventional resonator-based DWC can be generalized, and is linked to cross-phase modulation. Dispersion-engineered Si photonic crystal waveguides produce such slow-light pulses. Free carriers generated by two-photon absorption of the control pulse dynamically shift the signal wavelength. Matching the group velocities of the two pulses enhances the shift, elongating the interaction length. We demonstrate an extremely large wavelength shift in DWC (4.9nm blueshift) for the signal wavelength. Although DWC is similar to the Doppler effect, we highlight their essential differences.

Switching and dynamic wavelength conversion in a fiber grating cavity

Switching and dynamic wavelength conversion of light are demonstrated in a fiber grating cavity detuned by high-voltage electrical pulses. The cavity dynamics is studied using a heterodyne technique in which the frequency-shifted light, trapped by the cavity, mixes with the backreflected light at the incident frequency. We find that the frequency shift scales linearly with the energy of the electric driving pulses.

Single-Chip Wavelength Conversion Using a Photocurrent-Driven EAM Integrated With a Widely Tunable Sampled-Grating DBR Laser

Tunable photocurrent-driven wavelength converters using widely tunable sampled grating distributed Bragg reflector lasers, electroabsorption modulators, semiconductor optical amplifiers, and an optically preamplified receiver have been fabricated and tested. Dynamic wavelength conversion has been achieved over 40 nm with optical bandwidths up to 10 GHz.

All-optical bit-level retiming and jitter suppression

We demonstrate a novel all-optical bit-level retiming scheme by means of dynamic wavelength conversion and dispersion compensation. A linearly chirped, temporally square pulse is generated through self-phase modulation in a highly nonlinear fibre before being sampled by the incoming data inside an optical AND gate. Dispersion compensation of the sampled chirped pulse is then used to suppress both the timing jitter and phase wander simultaneously on a bit-by-bit level. Timing jitter of up to 3 ps rms at 10 Gbit/s is compensated for as well as phase wander of more than 30 ps.