From 9d8496be4cf2719c3dd7ca2a4b4de91ad4abeeb3 Mon Sep 17 00:00:00 2001 From: Blaise Thompson Date: Fri, 30 Mar 2018 13:54:43 -0500 Subject: 2018-03-30 13:54 --- opa/chapter.tex | 141 ++++++++++++++++++++++++++++++++++++++++++++++++++++++-- 1 file changed, 138 insertions(+), 3 deletions(-) (limited to 'opa/chapter.tex') diff --git a/opa/chapter.tex b/opa/chapter.tex index b92f62a..75459b5 100644 --- a/opa/chapter.tex +++ b/opa/chapter.tex @@ -1,4 +1,7 @@ -\chapter{A robust, fully automated algorithm to collect high quality OPA tuning curves} +% TODO: DONALDSON HAS AUTOMATED OPA TUNING DOWN? + +\chapter{A robust, fully automated algorithm to collect high quality OPA tuning + curves} \label{cha:opa} \begin{dquote} Principle design features of the new EVV 2DIR optical delivery system include the following: @@ -13,6 +16,138 @@ \clearpage -This chapter pasted from publication... +In frequency-domain Multi-Resonant Coherent Multidimensional Spectroscopy (MR-CMDS), automated +Optical Parametric Amplifiers (OPAs) are used to actively scan excitation color axes. % +To accomplish these experiments, exquisite OPA performance is required. % +During the experiment, motors inside the OPA move to pre-recorded positions to optimize output at +the desired color. % +Parametric conversion (``mixing'') strategies are now readily avalible, extending the 800 nm pumped +OPA tuning range into the visible, near-infrared, and mid-infrared. % + +OPAs are very sensitive to changes in upstream lasers and lab conditions, so OPA tuning is +regularly required. % +Manual OPA tuning can easily take a full day. % +Automated OPA tuning makes OPA upkeep easier, faster and more reproducible, facilitating frequency +domain experiments. % +The major challenges in automated OPA tuning are: +\begin{enumerate} + \item Expensive to take high resoltion data. + \item Need smooth curves for interpolation, especially at edges where output is low. + \item Optimization metrics are not necessarily separable along motor dimensions. +\end{enumerate} + +\section{Introduction} % ========================================================================= + +\section{TOPAS-C} % ============================================================================== + +% TODO: introduction to the internal design of the OPA + +\section{Preamp} % =============================================================================== + +\begin{figure} + \includegraphics[width=\textwidth]{opa/preamp} + \caption{ + CAPTION TODO + } + \label{opa:fig:preamp} +\end{figure} + +In TOPAS-C OPAs, a small portion of input light is used to generate a signal seed in a BBO crystal +``C1''. % +A motorized delay stage ``D1'' is used to temporally overlap a particular color in chirped white +light with 800 nm pump. % +C1 angle is tuned to optimize phase matching. % +Measured seed intensity and color for all combinations of C1 and D1 position are shown in +\autoref{fig:preamp}. % + +Output color and intensity are not separable along the preamp motor axes. % +We therefore use a multidimensional fitting strategy to find the best preamp motor positions, as +shown below. % + +% TODO: procedure + +\begin{figure} + \includegraphics[width=\linewidth]{opa/autotune_preamp} + \caption{ + CAPTION TODO + } + \label{opa:fig:autotune_preamp} +\end{figure} + +A representative preamp tune procedure output image is shown in \autoref{fig:autotune_preamp}. % +The thick black line is the final output curve. % +The dark grey lines are the contours of constant color. % +The colorbar shows the Delaunay-interpolated intensity values for each motor position. % + +Preamp tuning takes less than 20 minutes, in large part due to a NIR array detector which collects +the full spectrum at each motor position. % + +\section{Poweramp} % ============================================================================= + +\begin{figure} + \includegraphics[width=\linewidth]{opa/poweramp} + \caption{ + CAPTION TODO + } + \label{opa:fig:poweramp} +\end{figure} + +Once generated, the seed goes on to be amplified in a second BBO crystal ``C2'' with the rest of +the 800 nm pump. % +Optimizing this amplification step is primarily a matter of setting C2 angle. % +A small delay correction ``D2'' is necessary to account for dispersion in the seed optics. % +To fully explore poweramp behavior, we need to tak a C2-D23 scan for each seed color. % +Measured output intensity and color in this 3D space is represented in \autoref{fig:poweramp}. % +Note that the motor axes are scans about the previously recorded tuning curve value. % + +The best position (zero displacement along both axes) is chosen to maximize output intensity while +keeping the output color identical to the seed color. % +Optimizing for zero detuining rather than simply for output intensity has led to better OPA +performance and stability. % +Like in the preamp case, color and intensity are not fully separable along the poweramp motor +dimensions (this is especially true at the edge output colors). % +In the poweramp, the increased dimensionaity makes it too expensive to do a full multidimensional +tuning procedure. % +Instead we emply an iterative procedure as diagrammed below. % + +% TODO: procedure + +We always end the iteration(s) with C2 so that the OPA's color calibration is as good as +possible. % +Typically only one iteration is required but multiple iterations may be necessary if dramatic OPA +realignment has occurred. % +In total, poweramp tuning typically takes less than 1 hour. % +Representative procedure output images for D2 (\autoref{op:fig:d2}) and C2 (\autoref{opa:fig:c2}) +are shown. % + +\begin{figure} + \includegraphics[width=\textwidth]{opa/d2} + \caption{ + CAPTION TODO + } + \label{opa:fig:d2} +\end{figure} + +\begin{figure} + \includegraphics[width=\textwidth]{opa/c2}} + \caption{ + CAPTION TODO + } + \label{opa:fig:c2} +\end{figure} + +For the D2 figure, the lower panel shows the intensity of the data taken. % +Note the thick grey line, which represents the chosen points before the final spline step. % +The top panel compares the old tuning curve (thin) with the output tuning curve (thick). % +For the C2 image, the bottom panel represents the color of each fit mapped onto detuning. % +Each separate marker color represents a different setpoint. % +As with D2, the C2 upper panel compares the old tuning curve (thin black) with the output tuning +curve (colored X's). % + +\section{Mixers} % =============================================================================== + +\section{Generalizability} % ===================================================================== + +\section{Future directions} % ==================================================================== -% DONALDSON HAS AUTOMATED OPA TUNING DOWN? \ No newline at end of file +% TODO: discuss Attune \ No newline at end of file -- cgit v1.2.3