Single element Raman thermometry

Abstract

Despite a larger sensitivity to temperature as compared to other microscale thermometry methods, Raman based measurements typically have greater uncertainty. In response, a new implementation of Raman thermometry is presented having lower uncertainty while also reducing the time and hardware needed to perform the experiment. Using a modulated laser to excite the Raman response, the intensity of only a portion of the total Raman signal is leveraged as the thermometer by using a single element detector monitored with a lock-in amplifier. Implementation of the lock-in amplifier removes many sources of noise that are present in traditional Raman thermometry where the use of cameras preclude a modulated approach. To demonstrate, the portion of the Raman spectrum that is most advantageous for thermometry is first identified by highlighting, via both numerical prediction and experiment, those spectral windows having the largest linear dependence on temperature. Using such windows, the new technique, termed single element Raman thermometry (SERT), is utilized to measure the thermal profile of an operating microelectromechanical systems (MEMS) device and compared to results obtained with a traditional Raman approach. The SERT method is shown to reduce temperature measurement uncertainty by greater than a factor of 2 while enabling 3 times as many data points to be taken in an equal amount of time as compared to traditional Raman thermometry.

Experimental Characterization of the Thermal Time Constants of GaN HEMTs Via Micro-Raman Thermometry

“…It may be possible to do so with a single element photodetector and lock-in detection but this alternative implementation of micro-Raman thermography uses the total intensity over a certain spectral window rather than the Stokes peak position to measure temperature [41]. However, the approximate step or "pseudo-step" response can be obtained from a series of periodic pulse response measurements, such as the one shown in Fig.…”

A novel contactless technique for thermal field mapping and thermal conductivity determination: Two-Laser Raman Thermometry

“…Several electrical and optical techniques have been developed to measure the thermal conductivity of a large variety of materials and structures. [1][2][3][4][5][6][7][8][9][10][11][12][13] Optical methods have recently attracted considerable attention since most of them are contactless and, thus, require few sample preparation. Such techniques can be divided into two main categories: i) steady-state techniques, [3][4][5][6][7][8] and ii) transient techniques.…”

“…[1][2][3][4][5][6][7][8][9][10][11][12][13] Optical methods have recently attracted considerable attention since most of them are contactless and, thus, require few sample preparation. Such techniques can be divided into two main categories: i) steady-state techniques, [3][4][5][6][7][8] and ii) transient techniques. [9][10][11][12][13] An advantage of transient techniques is that they do not require the knowledge of the absorbed power in the sample since they are only sensitive to the thermal diffusivity, α = κ/ρC p (where ρ is the density and C p the specific heat), which is usually proportional to a characteristic decay time of the system.…”

Transient submicron temperature imaging based on the fluorescence emission in an Er/Yb co-doped glass–ceramic

“…Non-invasive techniques such as thermoreflectance [10][11][12], fluorescent thermometry [13][14][15][16][17], Raman thermometry [18][19][20], optical interferometry [2] and transmission electron microscopy [21] can achieve a submicron spatial resolution. However, most have very specific requirements that make them effective only under limited conditions [7,22,23].…”