Highest-data-rate laser diodes are key components in optical communications engineering. This experiment gives insights into the optical and electronic properties of laser diodes.

Semiconductor photodiodes of various types are evaluated for their effectivity in detecting weak light-pulses at optical communication wavelengths (800 nm to 1550 nm). They are important for error-free conversion of optical data back into the electrical domain.

Optical Coherence Tomography (OCT) is an imaging technique allowing for three-dimensional imaging with a spatial resolution on the scale of a few micrometres. Making use of an interferometric principle, it performs depth-resolved measurement of backscattered light inside the sample. Because of its high sensitivity OCT gained importance in various fields like ophthalmology, dermatology and material characterization.

In this experiment you will learn to acquire detailed measurement data with a free-space Swept-Source OCT-System and you will do the corresponding signal processing steps with Matlab.

This module gives an introduction to optical time domain reflectometry. This scheme monitors fiber optical links for changes in transmission quality or locations of damages to the fiber by evaluating backscattered signals. It is an important routine employed by all major telecommunication companies to check the integrity of optical links.

High refractive index contrast waveguides are used in integrated optical devices. Typical single mode planar and stripe waveguides are designed and characterized by beam propagation simulations with an industrial-standard high-frequency design-suite. This gives a graphic understanding of the actual transmission of light as an electromagnetic wave, extension of optical fields and of what is meant by “optical mode”.

Ring resonator waveguide structures are useful for adding or dropping information in networks switches. Their principle of operation is investigated with a microwave-frequency plug-and-play model (10 GHz).

Transmission and filtering properties are then experimentally verified with a network analyzer. Finally, finite-element-simulations are performed for visualization and a cross-check with theory.

In this module intensity- and phase-modulated 40 Gbit/s optical signals are generated, transmitted and received in a simulated environment (Rsoft OPTSIM).

Virtually all electrical and optical phenomena in communication networks can be simulated with this software. It is a valuable tool for cost-efficiently designing and testing new network components before actually employing them in real networks.

Quadrature Phase Shift Keying (QPSK), Quadrature Amplitude Modulation (QAM), or Orthogonal Frequency Division Multiplexing (OFDM) are important digital modulation formats used in radiofrequency (RF) applications, in radio-over-fiber (RoF) systems, and in optical communications systems.

In this module, digitally modulated signals are programmed in software, physically generated with an Arbitrary Waveform Generator (AWG; a fast digital to analog converter, DAC), recorded by a Digital Phosphor Oscilloscope (DPO; a fast analog to digital converter, ADC), and demodulated and evaluated in software. Strong emphasis of this experiment lies on the AWG and the DPO.