Development of a compact time-domain terahertz spectrometer using photoconductive antenna detection method

Download

index.pdf

Date

2009

Author

Güngör Erözbek, Ümmügül

Metadata

Show full item record

Item Usage Stats

255
views

108
downloads

In this thesis, we describe the development of a time-domain terahertz (THz) spectrometer driven by two different laser sources: an Er-doped femtosecond fiber laser and a mode-locked Ti:Sapphire laser. The resulting THz electromagnetic radiation was generated and detected using photoconductive antenna detection methods in both systems. In these experiments we characterized the THz power output for both the fiber laser driven system and the Ti:Sapphire laser driven system. Emphasis is given throughout this thesis on understanding the working principles behind time-domain terahertz spectroscopy, applications of THz radiation and terahertz generation as well as terahertz detection methods. We calculated the THz power output using two different methods. By using the “Hertzian Dipole” method we estimated the generated THz power after the generation photoconductive antenna. Using this method, we showed that the v generated power is on the order of milliwatts, which is far larger than the expected power typical for these systems. The second, “Open-Circuit Voltage” method, allowed us to calculate the received power on the detection photoconductive antenna. Using this method we were able to show that the THz power generated and detected in these systems is on the order of microwatts. For the mode-locked fiber laser driven spectrometer we obtained on average a ~ 4 ps (0.25 THz) pulse length which corresponded to an average power in the range of 71.8 nW - 70.54 ́W on a dipole antenna with a 6 ́m dipole gap and 44 ́m dipole length. Using the mode-locked Ti:Sapphire laser driven spectrometer we observed a ~ 2 ps (0.5 THz) pulse length and average power in the range of 0.54 nW 5.12 ́W on a different dipole antenna with a 5 ́m gap and 40 ́m dipole length. Since these values agree with expected values for these systems we believe the “Open-Circuit Voltage” method is appropriate when trying to calculate the THz power.

Subject Keywords

Physics., Optics, Light.

URI

http://etd.lib.metu.edu.tr/upload/3/12610440/index.pdf
https://hdl.handle.net/11511/18439

Collections

Graduate School of Natural and Applied Sciences, Thesis

Suggestions

OpenMETU
Core

Design and analysis of ultrashort femtosecond laser amplifiers Doğan, Ersin; Bilikmen, Kadri Sinan; Department of Physics (2006) This thesis presents a compact femtosecond laser amplifier design for optical preamplifiers and power amplifiers consist of theoretical perspective, simulations to analyze and optimize beam performance. The propagation through optical media is simulated for every optical component such as mirrors and nonlinear crystal separately and suggested realignment of these components required increasing amplifier performance. Finally Gaussian beam propagation and aberration compensation has been conducted.
Timing issues in a terawatt laser system Yılmaz, Remziye Pınar; Altan, Hakan; Department of Physics (2008) In the laser market, there have been various kinds of lasers designed and utilized for different purposes. As time goes on, their powers have been gradually increased from kilowatts (kW) to terawatts (TW). One of the most famous methods in laser science technology is Chirped Pulse Amplification (CPA) which enables table-top terawatt laser systems. This method provides high output power (tens of TW), very short pulse duration (few tens of femtoseconds) and large energy (mJ) for ultrafast lasers. One of the m...
Development of compact terahertz time-domain terahertz spectrometer using electro-optic detection method Metbulut, Mukaddes Meliz; Altan, Hakan; Department of Physics (2009) The goal of this thesis is to describe development of compact terahertz time-domain spectrometer driven by a mode-locked Ti:Sapphire laser. The terahertz radiation was generated by photoconductive antenna method and detected by electro-optic detection method. In this thesis, several terahertz generation and detection method, working principle of terahertz time-domain spectroscopy and its applications are discussed. We mainly focused on working principle of terahertz time-domain spectroscopy and characteriza...
Fundamentals of a metal surface imaging system based on laser-optic principles Bektaş, Murat; Altan, Hakan; Department of Physics (2009) The confocal laser-scanning microscope (CLSM), known simply as a confocal microscope, is an important instrument which allows us to observe an object or a surface in three-dimensions with confocal microcopy technique. The basic difference of confocal microscopy is detecting the in- focused light, while the out of focus light is blocked out by the help of a pinhole. By this optical dissection ability of confocal microcopy, CLSM provides the images of investigated object or the surface with higher resolution ...
Design and construction of a cw mode nd:YAG laser prototype Eryılmaz, Ertan; Esendemir, Akif; Department of Physics (2004) In this thesis a theoretical background of Nd:YAG lasers has been presented and key parameters of a design have been stated. Both pulsed mode and CW mode designs have been made; a 500mJ xenon flash lamp has been investigated as the pulsed light source and a 500W tungsten halogen lamp has been used as the continuous light source for optical pumping. Closed cooling system has been constructed. De-ionized water has been used as coolant. The goal has been acomplished by constructing a CW mode prototype. The out...

Citation Formats

Ü. Güngör Erözbek, “Development of a compact time-domain terahertz spectrometer using photoconductive antenna detection method,” M.S. - Master of Science, Middle East Technical University, 2009.