41 citations · 134 across the 8 of their papers we have counts for
8 papers
Enhancement of photoacoustic spectroscopy with sorption enrichment for ppt-level benzene detection
Juho Karhu, Tuomas Hieta
A real time trace gas detector for benzene is demonstrated. The measurement system takes an advantage of modest enrichment through short adsorption periods to reach a ppt-level det…
Cantilever-enhanced photoacoustic measurement of light-absorbing aerosols
Juho Karhu, Joel Kuula, Aki Virkkula +3
Photoacoustic detection is a sensitive method for measurement of light-absorbing particles directly in the aerosol phase. In this article, we demonstrate a new sensitive technique…
Mid-infrared frequency comb with 25 pJ threshold via CW-seeded optical parametric generation in nonlinear waveguide
Mikhail Roiz, Jui-Yu Lai, Juho Karhu +1
We demonstrate efficient generation of mid-infrared frequency combs based on continuous-wave-seeded femtosecond optical parametric generation in nonlinear waveguides. Conversion of…
Simple method for mid-infrared optical frequency comb generation with dynamic offset frequency tuning
Mikhail Roiz, Krishna Kumar, Juho Karhu +1
We present a simple method for fully-stabilized mid-infrared optical frequency comb generation based on single-pass femtosecond optical parametric generation that is seeded by a co…
High-resolution analysis of the band of radiocarbon methane
Santeri Larnimaa, Lauri Halonen, Juho Karhu +6
We present the first high-resolution measurements and rotational analysis of the fundamental asymmetric stretching vibrational band of radiocarbon methane. A spectrome…
Broadband photoacoustic spectroscopy of with a high-power mid-infrared optical frequency comb
Juho Karhu, Teemu Tomberg, Francisco Senna Vieira +7
We report a photoacoustic spectroscopy setup with a high-power mid-infrared frequency comb as the light source. The setup is used in broadband spectroscopy of radiocarbon methane.…
Fully Stabilized Mid-Infrared Frequency Comb for High-Precision Molecular Spectroscopy
Markku Vainio, Juho Karhu
A fully stabilized mid-infrared optical frequency comb spanning from 2.9 to 3.4 um is described. The comb is based on half-harmonic generation in a femtosecond optical parametric o…
Double resonant absorption measurement of acetylene symmetric vibrational states probed with cavity ring down spectroscopy
J. Karhu, J. Nauta, M. Vainio +3
A novel mid-infrared/near-infrared double resonant absorption setup for studying infrared-inactive vibrational states is presented. A strong vibrational transition in the mid-infra…