Implantable photonic probes are of increasing interest to the field of biophotonics and in particular, optogenetic neural stimulation. Active probes with onboard light emissive elements allow for electronic multiplexing and can be manufactured through existing microelectronics methods. However, as the optogenetics field moves towards clinical practice, an important question arises as to whether such probes will cause excessive thermal heating of the surrounding tissue. Light emitting diodes typically produce more heat than light. The resultant temperature rise of the probe surface therefore needs to be maintained under the regulatory limit of 2°C. This work combines optical and thermal modelling, which have been experimental verified. Analysis has been performed on the effect of probe/emitter geometries, emitter, and radiance requirements. Finally, the effective illumination volume has been calculated within thermal limits for different probe emitter types and required thresholds.

The inherent advantages of fiber optical current transformer (FOCT) are very attractive for high-voltage applications when compared with conventional transformers. However, the accuracy and long-term reliability of FOCT can be greatly affected by temperature. Fiber temperature sensors are suitable for FOCT temperature compensation, especially in UHV applications. As a result, a fiber temperature sensing scheme based on the temperature birefringence effect of polarization maintaining fiber (PMF-TS) was proposed. A high integration real-time temperature correction FOCT based on PMF-TS (PMFTS-FOCT) was designed, and a prototype with rated current of 5000A and rated voltage of 1100kV was developed. The accuracy, temperature, frequency response, step response and transient response of the system was tested. The results showed that within the temperature range of -40°C~;70°C, the ratio error (RE) of 500A~5500A was less than ±0.2% after temperature correction, and in the frequency range of 50Hz~1200Hz, RE and phase error (PE) were less than ±0.75% and 110μs, respectively. The step response time was less than 125μs, the overshoot was less than 1.5%, and the composite error was 0.807% for the 50,000A transient current. We proved that PMFTS-FOCT had good steady-state and transient performance and possibility for measuring DC and AC harmonics, whose performance meets the error limit requirements specified in GB/T 26216.1-2010.

An integrated microstrip meander line (MML) slow-wave structure (SWS) comprised of an MML SWS and compact wideband metamaterial absorber (MMA) is proposed and demonstrated theoretically and experimentally in this paper. The MMA consists of metallic rectangular resonators with a metallic ground plane and a separating dielectric layer. Simulation results show that the MMA has multidistinctive absorption peaks; the bandwidth at 56-GHz peak frequency is reach up to 30 GHz. The integrated MML SWS can provide flatter gain response of output power than that made by the MML SWS with a traditional resistive coating attenuator. Experimental results are in close agreement with simulation results. A traveling wave tube (TWT) is simulated based on this integrated MML SWS. The output power of this TWT is 48.21 W at 33 GHz corresponding to a maximum gain of 30.3 dB; the output power gain is greater than 25 dB across the entire working frequency range.

There is a growing demand for the development of new types of implantable optoelectronics to support both basic neuroscience and optogenetic treatments for neurological disorders. Target specification requirements include multi-site optical stimulation, programmable radiance profile, safe operation, and miniaturization. It is also preferable to have a simple serial interface rather than large numbers of control lines. This paper demonstrates an optrode structure comprising of a standard complementary metal-oxide-semiconductor process with 18 optical stimulation drivers. Furthermore, diagnostic sensing circuitry is incorporated to determine the long-term functionality of the photonic elements. A digital control system is incorporated to allow independent multisite control and serial communication with external control units.

A dual media access control (DMAC) based hierarchical optical access network (HOAN) is proposed for data center networks, consisting of passive optical distribution modules (PODMs) at passive optical access layer and top-of-cluster (ToC) switches at electronic access layer. A PODM organizes a group of servers into a computing cluster and forms the intra-cluster channel. Each ToC switch connected with several PODMs forms the inter-cluster channel based on time and wavelength division multiplexing (TWDM). A load-sensing dual-mode (LSDM) protocol is presented for the intra-cluster channel to realize distributed low-load competition and high-load polling operation; the inter-cluster channel applies any polling based TWDM protocol to offer flexible bandwidth allocation. Simulations show that the LSDM can reach 0.95 throughputs at high traffic load, less than 32 μs frame latency, 128 μs frame latency on the 99.9th percentile of the simulated results at 25 Gbps with high priority, verifying the LSDM protocol can realize high throughput, low latency and the measured latency variation. Compared the performances of DMAC based HOAN with those of passive optical cross-connection network and passive optical top-of-rack interconnect architecture, when the normalized intra-rack traffic load reaches 0.8, average frame latencies in one computing cluster are 70.4, 184, and 2480 μs at 10 Gbps, and normalized available bandwidths for inter-cluster channels are 1, 0.2, and 0.2, respectively. Furthermore, the DMAC based HOAN is characterized with the scalability capable of organizing up to 320000 servers with only 500 ToC switches.