Laser and Optics

Title: Laser Communication for Small Satellites
Faculty Mentor: Dr. Volker Quetschke

Recent technological advances have enabled new classes of spacecraft known as “SmallSats”, “Micro-Sats”, “CubeSats”, and even “chip-sats”. Leveraging the overall miniaturization of electronic devices, it is now becoming viable to build relatively inexpensive, small scale, light weight spacecraft that can accomplish a wide variety of scientific and engineering goals in space. Inter satellite communication has been developed since the 1980’s and communication links in space have been demonstrated, for example the ARTEMIS project from ESA using direct detection or the NFIRE project from NASA using coherent detection. Unfortunately the costs of these systems has prohibited the use of those technologies for the more affordable small satellites.  At CARA we currently develop a low-cost laser communication system based on commercial fiber-optic technologies and components, but replacing the fiber with a free space laser beam instead. REU student projects have the opportunity to work on light communication related research, as well as other small satellite communication related experiments. The students will first learn laser safety before being guided through the applications of (low-power) laser light.

Title: Terahertz time-domain spectroscopy for characterizing optical materials
Faculty Mentor: Dr. Myoung-Hwan Kim

Two-dimensional optical materials called metasurfaces form arrays of resonant optical scatterers in subwavelength scale. These arrays provide spatially varying optical responses including phase, amplitude, polarization, and impedance of light. They allow the metasurfaces to mold wavefronts of light causing arbitrary reflection and refraction in a desired way. Optical materials for controlling a free space terahertz (THz) light have been studied very recently although high gigahertz (GHz) opto-electronic control has already been achieved. THz optical materials will benefit quality control in industry, security screening, medical diagnostic device development, and pharmaceutical research. The laboratory project in REU comprises two sessions: metasurface sample preparation and THz spectrum measurement. The REU students will practice micro-fabrication by using a high-resolution 3D printer and sputter coater in Dr. Karen Martirosyan’s lab in the Physics Department to make optical materials of THz reflective antenna arrays. The students will learn how to design metasurfaces by using a commercial full-wave simulation (Finite-difference time-domain solutions by Lumerical, Inc.). The THz time-domain spectroscopy system (THz-TDS) has been set up at Dr. Kim’s laboratory. The system uses an ultrafast Ti:Sapphire laser (Tsunami, Spectra-Physics) to generate and detect a broadband THz light from electro-optic ZnTe crystals. The student will first learn laser safety and then the concept of the THz-TDS system. They will learn how to achieve THz beam alignment for transmission and reflection measurement to characterize THz optical materials and how to take THz spectrum from the materials.