An exemplary medical system includes a first electrical circuit (204-1) on a PCB (206), a second electrical circuit (204-2) on the PCB and electrically isolated from the first electrical circuit, and a free space optics interface assembly (302) on the PCB. The free space optics assembly includes a housing (402) defining a free space chamber (404) in the housing, an optical transmitter (416) having an input (426) that is electrically coupled to the first electrical circuit, and an optical receiver (418) in optical communication with the optical transmitter via the free space chamber and having an output (432) that is electrically coupled to the second electrical circuit. The optical transmitter and the optical receiver are hermetically sealed within the housing.

Low-noise optical differential receivers are described. Such differential receivers may include a differential amplifier having first and second inputs and first and second outputs, and four photodetectors. A first and a second of such photodetectors are coupled to the first input of the differential amplifier, and a third and a fourth of such photodetectors are coupled to the second input of the differential amplifier. The anode of the first photodetector and the cathode of the second photodetector are coupled to the first input of the differential amplifier. The cathode of the third photodetector and the anode of the fourth photodetector are coupled to the second input of the differential amplifier. The optical receiver may involve two stages of signal subtraction, which may significantly increase noise immunity.

A downhole optical communications system provided at a downhole location in use, the downhole communications system being for communicating between the downhole location and an uphole location, such as a surface location. The downhole optical communications system comprises a downhole optical transmitter configured to emit an optical signal for transmission over an optical transmission channel between the uphole location and the downhole optical transmitter; wherein the downhole optical transmitter is configured so as to produce a response to an optical signal received from the optical transmission channel and the downhole optical communications system is configured to determine data represented by the received optical signal from the response produced by the downhole optical transmitter.

A signal processing device included in an optical reception device configured to receive a burst optical signal transmitted by one of a plurality of optical transmission devices, includes a symbol timing detecting unit configured to detect a symbol timing based on sample signals obtained by oversampling the burst optical signal converted into an electric signal with a sampling rate higher than a symbol rate, an adaptive equalization filter unit configured to perform an equalization process on the sample signals, and a timing matching unit configured to match timing such that, when the adaptive equalization filter unit takes in the sample signals, one of the taken-in sample signals corresponding to the symbol timing is given to a tap of which a tap coefficient has a maximum value among taps included in the adaptive equalization filter unit.

A signal processing device included in an optical reception device configured to receive a burst optical signal transmitted by one of a plurality of optical transmission devices, includes a symbol timing detecting unit configured to detect a symbol timing based on sample signals obtained by oversampling the burst optical signal converted into an electric signal with a sampling rate higher than a symbol rate, an adaptive equalization filter unit configured to perform an equalization process on the sample signals, and a timing matching unit configured to match timing such that, when the adaptive equalization filter unit takes in the sample signals, one of the taken-in sample signals corresponding to the symbol timing is given to a tap of which a tap coefficient has a maximum value among taps included in the adaptive equalization filter unit.

Materials containing picocrystalline quantum dots that form artificial atoms are disclosed. The picocrystalline quantum dots (in the form of born icosahedra with a nearly-symmetrical nuclear configuration) can replace corner silicon atoms in a structure that demonstrates both short range and long-range order as determined by x-ray diffraction of actual samples. A novel class of boron-rich compositions that self-assemble from boron, silicon, hydrogen and, optionally, oxygen is also disclosed. The preferred stoichiometric range for the compositions is (B.sub.12H.sub.w).sub.xSi.sub.yO.sub.z with 3≤w≤5, 2≤x≤4, 2≤y≤5 and 0≤z≤3. By varying oxygen content and the presence or absence of a significant impurity such as gold, unique electrical devices can be constructed that improve upon and are compatible with current semiconductor technology.

There are described methods and devices for intra-spacecraft communication in space, the electro-optical device having at least one of transmitting capabilities for converting a first electrical signal into a first optical signal and outputting the first optical signal within a spacecraft, and receiving capabilities for receiving a second optical signal within the spacecraft and converting the second optical signal into a second electrical signal, the electro-optical device having at least one integrated circuit dedicated to at least one of the transmitting capabilities and the receiving capabilities, the at least one integrated circuit configured for operating in an analog mode where configuration voltages for the integrated circuit are provided by analog voltage settings unaffected by radiation.

In order to measure the signal quality of each of optical signals transmitted/received via a plurality of transmission lines, an optical communication system 1 is provided with a dummy light source 10 for outputting dummy light, a switching means 20 for outputting the dummy light to a first transmission line 40a, and a light-receiving means 30 for acquiring first signal quality from the dummy light received via the first transmission line 40a, the switching means 20 switching the output destination of the dummy light from the first transmission line 40a to a second transmission line 40b, and the light-receiving means 30 acquiring second signal quality from the dummy light received via the second transmission line 40b.

This optical communication device (1) is provided with: a plurality of light-receiving elements (11) configured to receive communication light, the plurality of light-receiving elements being provided so as to correspond to a plurality of channels; and a controller (15) configured to perform control to invalidate output from a light-receiving element that has received high-intensity light higher in light intensity than a predetermined value among the plurality of light-receiving elements.

This optical communication device (1) is provided with: a plurality of light-receiving elements (11) configured to receive communication light, the plurality of light-receiving elements being provided so as to correspond to a plurality of channels; and a controller (15) configured to perform control to invalidate output from a light-receiving element that has received high-intensity light higher in light intensity than a predetermined value among the plurality of light-receiving elements.