Optical link

Abstract: We report error free ( $\textrm {BER} ) operation of a directly non-return-to-zero modulated 850-nm vertical cavity surface-emitting laser (VCSEL) link operating to 71 Gb/s. This is the highest error free modulation rate for a directly modulated laser of any type. The optical link consists of a 130-nm BiCMOS driver IC with two-tap feed-forward equalization, a wide bandwidth 850-nm VCSEL, a surface illuminated GaAs PIN photodiode, and a 130-nm BiCMOS receiver IC.

Abstract: We experimentally investigate the performance of an orbital angular momentum (OAM) multiplexed free space optical (FSO) communication link through emulated atmospheric turbulence. The turbulence effects on the crosstalk and system power penalty of the FSO link are characterized. The experimental results show that the power of the transmitted OAM mode will tend to spread uniformly onto the neighboring mode in medium-to-strong turbulence, resulting in severe crosstalk at the receiver. The power penalty is found to exceed 10 dB in a weak-to-medium turbulence condition due to the turbulence-induced crosstalk and power fluctuation of the received signal.

Abstract: PROBLEM TO BE SOLVED: To decrease the number of times of transmission of a reset signal for a network which decides the topology of a bus in compliance with, e.g. the IEEE 1394 to a minimum number of times in a communication network, such as a LAN. SOLUTION: An optical transmitter 1 (2, 11) is a device that optically transmits a twisted pair signal used for a network such as a LAN and a serial bus and consists mainly of a transceiver section 101 that sends/receives data to/from a terminal 100, a code conversion section 102, that encodes data received from the transceiver section 101 into optical transmission data, an optical transmission section 103 and an optical reception section 104 that send/receive data to/from other optical transmitter being a communication opposite party, and optical data detection section 105 that detects a level of a signal received by the optical reception section 104, a state notice section 106 that informs the terminal equipment 100 of the communication state, and an optical link generating section 107 that generates prescribed data, when the optical transmission is in shielded state.

Abstract: Broadband electro-optic intensity modulators are essential to convert electrical signals to the optical domain. The growing interest in terahertz wireless applications demands modulators with frequency responses to the sub-terahertz range, high power handling, and very low nonlinear distortions, simultaneously. However, a modulator with all those characteristics has not been demonstrated to date. Here, we experimentally demonstrate that plasmonic modulators do not trade-off any performance parameter, featuring—at the same time—a short length of tens of micrometers, record-high flat frequency response beyond 500 GHz, high power handling, and high linearity, and we use them to create a sub-terahertz radio-over-fiber analog optical link. These devices have the potential to become a new tool in the general field of microwave photonics, making the sub-terahertz range accessible to, e.g., 5G wireless communications, antenna remoting, Internet of Things, sensing, and more.