Methods and apparatus for characterizing optical fiber links by optical time-domain reflectometry are disclosed. To resolve compromises between the signal-to-noise ratio, duration, and resolution of optical-time domain reflectometry measurements, embodiments of the present disclosure use coded sequences of return-to-zero light pulses. Each return-to-zero light pulse in a coded sequence includes a guard interval to mitigate the effects of pulse shape distortions. In some embodiments, the sequences of return-to-zero light pulses encode complementary Golay correlation codes. Some embodiments provide methods for encoding and decoding the sequences of return-to-zero pulse sequences. Some embodiments provide an optical time-domain reflectometry apparatus including a light source unit, optical coupler, light sensor, and processing device.

Systems and methods are described for transmitting information optically. For instance, a system may include an optical source configured to generate a beam of light. The system may include at least one modulator configured to encode data on the beam of light to produce an encoded beam of light/encoded plurality of pulses. The system may include a spectrally-equalizing amplifier configured to receive the encoded beam of light/encoded plurality of pulses from the at least one modulator and both amplify and filter the encoded beam of light/encoded plurality of pulses to produce a filtered beam of light/filtered plurality of pulses, thereby spectrally equalizing a gain applied to the encoded beam of light. In some cases, the system may slice the beam of slight, to ensure a detector has impulsive detection. In some cases, the system may include a temperature controller to shift a distribution curve of wavelengths of the optical source.

A driver circuit for supplying and regulating power to a micro light-emitting diode (micro-LED), the driver circuitry comprising: at least one inverter; a first capacitance; a resistor coupled to ground; a fast switch comprising at least one first transistor; and a slow switch comprising at least one second transistor; whereby at least one of a rising time, a peaking effect, and LED power is increased.