Demonstration of a room temperature 2.48-2.75 THz coherent spectroscopy source.

We report the first demonstration of a continuous wave coherent source covering 2.48-2.75 THz, with greater than 10% instantaneous tuning bandwidth and having 1-14 μW of output power at room temperature. This source is based on a 91.8-101.8 GHz synthesizer followed by a power amplifier and three cascaded frequency triplers. It demonstrates for the first time that purely electronic solid-state sources can generate a useful amount of power in a region of the electromagnetic spectrum where lasers (solid state or gas) were previously the only available coherent sources. The bandwidth, agility, and operability of this THz source have enabled wideband, high resolution spectroscopic measurements of water, methanol, and carbon monoxide with a resolution and signal-to-noise ratio unmatched by any other existing system, providing new insight in the physics of these molecules. Furthermore, the power and optical beam quality are high enough to observe the Lamb-dip effect in water. The source frequency has an absolute accuracy better than 1 part in 10(12) and the spectrometer achieves sub-Doppler frequency resolution better than 1 part in 10(8). The harmonic purity is better than 25 dB. This source can serve as a coherent signal for absorption spectroscopy, a local oscillator for a variety of heterodyne systems and can be used as a method for precision control of more powerful but much less frequency agile quantum mechanical terahertz sources.

[1]  R. Dicke.  The effect of collisions upon the Doppler width of spectral lines , 1953 .

[2]  Walter Gordy,et al.  One-to-Two Millimeter Wave Spectroscopy. IV. Experimental Methods and Results for OCS, CH3F, andH2O , 1954 .

[3]  D. Hogg,et al.  Millimeter-Wave Communication through the Atmosphere: The known and unknown features in propagation of short radio waves are discussed. , 1968, Science.

[4]  D. R. Mattson.  Sensitivity of a Fourier Transform Infrared Spectrometer , 1978 .

[5]  H M Pickett,et al.  Determination of collisional linewidths and shifts by a convolution method. , 1980, Applied optics.

[6]  H M Pickett,et al.  Chlorine Monoxide Radical, Ozone, and Hydrogen Peroxide: Stratospheric Measurements by Microwave Limb Sounding , 1981, Science.

[7]  W. Duncan,et al.  Infrared synchrotron radiation from electron storage rings. , 1983, Applied optics.

[8]  K. Evenson,et al.  Tunable far-infrared spectroscopy , 1984 .

[9]  M. A. Frerking,et al.  Generation of tunable laser sidebands in the far‐infrared region , 1985 .

[10]  Drakopoulos,et al.  Far-infrared rotational spectrum of HD: Line shape, dipole moment, and collisional interference. , 1987, Physical review. A, General physics.

[11]  K. Evenson,et al.  Frequency measurement of the J = 1-0 rotational transition of HD , 1988 .

[12]  D. Grischkowsky,et al.  Terahertz time-domain spectroscopy of water vapor. , 1989, Optics letters.

[13]  K. Evenson,et al.  Accurate far-infrared rotational frequencies of carbon monoxide , 1992 .

[14]  E. Lellouch.  Solar system observations and future missions , 1995 .

[15]  Kojiro Takagi,et al.  Frequency measurement of pure rotational transitions of H20 from 0.5 to 5 THz , 1995 .

[16]  Richard D. Suenram,et al.  A Terahertz Photomixing Spectrometer: Application to SO2Self Broadening , 1996 .

[17]  Robert M. Weikle,et al.  Proceedings of the Tenth International Symposium on Space Terahertz Technology , 1999 .

[18]  Bromm,et al.  Forming the First Stars in the Universe: The Fragmentation of Primordial Gas. , 1999, The Astrophysical journal.

[19]  F. Bertoldi,et al.  Detection of HD in the Orion molecular outflow , 1999, astro-ph/9904261.

[20]  Optical phonon dynamics of GaAs studied with time-resolved terahertz spectroscopy. , 2000, Optics letters.

[21]  Winnewisser,et al.  Precision Broadband Spectroscopy near 2 THz: Frequency-Stabilized Laser Sideband Spectrometer with Backward-Wave Oscillators. , 2000, Journal of molecular spectroscopy.

[22]  John C. Pearson,et al.  A tunable cavity-locked diode laser source for terahertz photomixing , 2000 .

[23]  P. Goy,et al.  A Vector Analyzer for Observing Millimeter-Submillimeter Resonances , 2000, 2000 30th European Microwave Conference.

[24]  I. Mehdi,et al.  Fabrication of 200 to 2700 GHz multiplier devices using GaAs and metal membranes , 2001, 2001 IEEE MTT-S International Microwave Sympsoium Digest (Cat. No.01CH37157).

[25]  A long-wavelength view on galaxy evolution from deep surveys by the Infrared Space Observatory , 2001, astro-ph/0108292.

[26]  E. Linfield,et al.  Terahertz semiconductor-heterostructure laser , 2002, Nature.

[27]  Lorene Samoska,et al.  W band power amplifier development for the Herschel HIFI instrument , 2003, SPIE Astronomical Telescopes + Instrumentation.

[28]  Fritz Keilmann,et al.  Time-domain mid-infrared frequency-comb spectrometer. , 2004, Optics letters.

[29]  I. Mehdi,et al.  A 1.7-1.9 THz local oscillator source , 2004, IEEE Microwave and Wireless Components Letters.

[30]  I. Mehdi,et al.  An all-solid-state broad-band frequency multiplier chain at 1500 GHz , 2004, IEEE Transactions on Microwave Theory and Techniques.

[31]  John C. Pearson,et al.  Application of cascaded frequency multiplication to molecular spectroscopy , 2005 .

[32]  I. Mehdi,et al.  Local oscillator chain for 1.55 to 1.75THz with 100-/spl mu/W peak power , 2005, IEEE Microwave and Wireless Components Letters.

[33]  B. Williams,et al.  Frequency and phase-lock control of a 3?THz quantum cascade laser , 2005 .

[34]  Holger S. P. Müller,et al.  The Cologne Database for Molecular Spectroscopy, CDMS: a useful tool for astronomers and spectroscopists , 2005 .

[35]  David A. Ritchie,et al.  High-resolution gas phase spectroscopy with a distributed feedback terahertz quantum cascade laser , 2006 .

[36]  Cristina Puzzarini,et al.  The Lamb-dip spectrum of methylcyanide: Precise rotational transition frequencies and improved ground-state rotational parameters , 2006 .

[37]  Choonsup Lee,et al.  In-Phase Power-Combined Frequency Triplers at 300 GHz , 2008, IEEE Microwave and Wireless Components Letters.

[38]  C. Puzzarini,et al.  Lamb-dip spectrum of methylacetylene and methyldiacetylene: precise rotational transition frequencies and parameters of the main isotopic species , 2008 .

[39]  Brian J. Drouin,et al.  Torsion–rotation global analysis of the first three torsional states (νt = 0, 1, 2) and terahertz database for methanol , 2008 .

[40]  R. Colombelli,et al.  Electrically pumped photonic-crystal terahertz lasers controlled by boundary conditions , 2009, Nature.

[41]  G. Mouret,et al.  THz photomixing synthesizer based on a fiber frequency comb. , 2009, Optics express.

[42]  J. Gauss,et al.  The hyperfine structure in the rotational spectrum of water: Lamb-dip technique and quantum-chemical calculations , 2009 .

[43]  M Fischer,et al.  Phase locking of a 1.5 Terahertz quantum cascade laser and use as a local oscillator in a heterodyne HEB receiver. , 2009, Optics express.

[44]  Choonsup Lee,et al.  A Broadband 835–900-GHz Fundamental Balanced Mixer Based on Monolithic GaAs Membrane Schottky Diodes , 2010, IEEE Transactions on Microwave Theory and Techniques.

[45]  W. Deal,et al.  Solid-state amplifiers for terahertz electronics , 2010, 2010 IEEE MTT-S International Microwave Symposium.

[46]  Miguel de Val-Borro,et al.  First results of Herschel-PACS observations of Neptune , 2010, 1006.0114.

[47]  J. Prochaska,et al.  COSMOLOGICAL CONCORDANCE OR CHEMICAL COINCIDENCE? DEUTERATED MOLECULAR HYDROGEN ABUNDANCES AT HIGH REDSHIFT , 2010, 1007.0030.

[48]  Choonsup Lee,et al.  A Frequency-Multiplied Source With More Than 1 mW of Power Across the 840–900-GHz Band , 2010, IEEE Transactions on Microwave Theory and Techniques.

[49]  F. D. Lucia.  The submillimeter: A spectroscopist’s view , 2010 .

[50]  David A. Ritchie,et al.  Submegahertz frequency stabilization of a terahertz quantum cascade laser to a molecular absorption line , 2010 .

[51]  P. Kangaslahti,et al.  W-Band GaN MMIC with 842 mW output power at 88 GHz , 2010, 2010 IEEE MTT-S International Microwave Symposium.