We demonstrate wavelength-division multiplexed (WDM) and mode-division multiplexed (MDM) transmission over a
fiber recirculating loop comprising of a 25-km span of low differential mode group dispersion (DMGD) few-mode fiber
carrying the LP01 and LP11 mode groups, and an inline few-mode erbium-doped fiber amplifier (FM-EDFA) providing
low mode-dependent gain (MDG) per span. We successfully transmitted a 10λ × 6 × 28-Gbaud QPSK signal over a
distance of 700 km.
We report the first terabit/s superchannel transmission over a submarine distance >10,000 km. Four 1.15-Tb/s
superchannels, each consisting of 23 optical subcarriers at 12.5-GHz spacing are modulated with DP-QPSK at 12.5
Gbaud. The WDM signal is transmitted over 168×60.6-km spans of hybrid large-core/ultra low-loss fibers with inline
amplification by low noise C-band EDFAs. The system achieved a Q-factor margin of 2 dB assuming the use of HDFEC,
and a spectral efficiency of 3.6 b/s/Hz is achieved.
One integrated pair of OCDMA encoder and decoder based on holographic Bragg reflector technology was designed and fabricated to simultaneously provide two multiple wavelength-hopping time-spreading optical codes. We have successfully demonstrated an encoding/decoding operation of two codes in 1.25-Gbps OCDMA testbed. A double-pass scheme was employed, enabling the implementation of much longer code length.
We review some experimental and theoretical aspects of coherent acoustic phonon generation in piezoelectric semiconductor multiple quantum wells. In order to model more advanced and complicated nano-acoustic devices, a macroscopic continuum theory for the generation and propagation of coherent acoustic phonons in piezoelectric semiconductor heterostructures is presented. The macroscopic approach is applicable in the coherent regime, and can be easily utilized to study coherent acoustic devices based on piezoelectric semiconductor
heterosutructures. For each phonon mode, the corresponding coherent acoustic field obeys a loaded string equation. The driven force has contributions from the piezoelectric and deformation potential couplings. We applied the theory to model the generation of coherent
longitudinal acoustic phonons in (0001)-oriented InGaN/GaN multiple quantum wells. The numerical results are in good agreement with the experimental ones. By using the macroscopic theory, we also investigated the crystal-orientation effects on the generation of coherent acoustic phonons in wurtzite multiple quantum wells. It was found that coherent transverse acoustic phonons dominate the generation for certain orientation angles.
One of the most desirable properties of phonon system is sound amplification by stimulated emission of phonon radiation, coined as SASER or called phonon laser or acoustic laser, which is the acoustic counterpart of LASER. Phonon stimulated emission, or sound amplification, has been previously observed fro several occasions in extremely low temperatures, however a lasing behavior of the phonon oscillators has never been established. It is also desirable to build a phonon laser operating at room temperature. Here we present an optically pumped nano-sized phonon laser with an output acoustic wavelength of 9.3 nm, operating at room temperature. The nano phonon laser is composed by InGaN/GaN multiple-quantum-wells (MQWs). By using femtosecond ultraviolet pulses as pumping sources, coherent acoustic phonon amplification with large acoustic gain was observed. When the induced acoustic gain is higher than the acoustic loss due to its traveling nature, a clear laser-like threshold behavior was observed, which resembles a pulsed optical laser. This demonstration will open a new way toward nano-ultrasonics.