\input{preamble.tex}
\graphicspath{{images}, {images/1550}}

\title{1550 Laser Diode Driver Kirdy}
\author{M-Labs Limited}
\date{January 2025}
\revision{Revision 0}
\companylogo{\includegraphics[height=0.73in]{artiq_sinara.pdf}}

\begin{document}
\maketitle

\section{Features}

    \begin{itemize}
        \item{300mA max output current, 20-bit resolution}
        \item{Low noise current source}
        \item{18MHz-bandwidth modulation input}
        \item{Monitor photodiode and LD protection}
        \item{Built-in sub-mK stability temperature controller}
        \item{Full digital control over Ethernet}
    \end{itemize}

\section{Applications}

    \begin{itemize}
        \item{High-precision laser driver}
        \item{Suitable for use with adapter and preinstalled laser assembly or with external laser heads}
        \item{Spectroscopy and other atomic physics applications}
    \end{itemize}

\section{General Description}

    The 1550 Laser Diode Driver Kirdy is a 8hp EEM form factor module, and part of the Sinara open hardware family. It serves as a precision laser diode driver, featuring a low-noise current source, low- and high-frequency modulation inputs, and full digital control over Ethernet. Soft turn-on, laser power monitoring with a user-defined trip point, overtemperature protection, and a protection relay minimize the risk of damage to the laser diode.

    1550 Kirdy supports both low-frequency modulation, suitable for laser locks and linewidth reduction, as well as RF modulation injected directly into the diode, typically to inject sidebands into the beam and implement stabilization schemes such as Pound-Drever-Hall and modulation transfer spectroscopy.

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\begin{figure}[hbt!]
    \centering
    \includegraphics[height=2.5in]{photo1550.jpg}
    \caption{Kirdy card photo}
    \includegraphics[height=3in, angle=90]{fp1550.pdf}
    \caption{Kirdy front panel}
\end{figure}

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% page-by-page.
\onecolumn

\sourcesection{1550 Laser Diode Driver Kirdy}{https://git.m-labs.hk/sinara-hw/kirdy} The associated adapter can be found at the repository /url{https://git.m-labs.hk/sinara-hw/kirdyAdapter/src/branch/master}.

\section{Technical Specifications}

    % microcontroller datasheet: \url{https://www.st.com/resource/en/datasheet/DM00037051.pdf}

    % Numbers currently taken unquestioned from the repo https://git.m-labs.hk/sinara-hw/kirdy/

    \begin{table}[h]
        \centering
        \begin{threeparttable}
        \caption{Technical Specifications}
        \begin{tabularx}{0.75\textwidth}{l | c c c | c | X}
            \thickhline
            \textbf{Parameter} & \textbf{Min.} & \textbf{Typ.} & \textbf{Max.} &
            \textbf{Unit} & \textbf{Conditions} \\
            \hline
            Output power & & & 300 & mA & \\
            \hline
            Compliance & & 4 & & V & \\
            \hline
            Bandwidth & & 50 & & Hz & \\
            \hline
            Current noise & & 300 & & pA/$\sqrt{}$Hz & @ 1kHz \\
            RMS noise & & 300 & & nA & over 10Hz - 1MHz \\
            \hline
            Photodiode current & 0 & & 2.5 & mA & \\
            \hline
            TEC controller & & & & & \\
            \hspace{3mm} Output power & & & 1 & A & \\
            \hspace{3mm} Compliance & & 5 & & V & \\
            \hspace{3mm} Stability & & +/- 1 &  & mK & \\
            \thickhline
        \end{tabularx}
        \end{threeparttable}
    \end{table}

    1550 Kirdy supports Power-over-Ethernet. Alternatively, power can be provided via 12V DC input in front panel.

\section{Modulation inputs}

    1550 Kirdy supports two additional modulation inputs via SMA in the front panel, respectively \texttt{HF MOD} for high-frequency and \texttt{LF MOD} for low-frequency. Modulation input may be DC to 10MHz (+/- 1V max), with gain adjustable by DIP switch in top right of board.

    \begin{multicols}{2}

        \begin{center}
        \captionof{table}{DIP switch configurations}
            \begin{tabular}{|l|c|}
            \hline
            \textbf{Switch} & \textbf{Setting} \\
            \thickhline
            3 & 0.25 mA/V \\
            2 & 2.5 mA/V \\
            1 & 25 mA/V \\
            \thickhline
            \end{tabular}
        \end{center}

        \columnbreak

        \begin{center}
            \centering
            \includegraphics[height=1.5in]{kirdy_mod_switch.jpg}
            \captionof{figure}{Position of DIP switch}
        \end{center}

    \end{multicols}

\newpage
\section{Adapter and Laser Options}

    An optional adapter allows compact lasers in butterfly packages to be mounted directly onto 1550 Kirdy, with a fibre-optic output in the front panel. Multiple single-frequency narrow-linewidth lasers are currently available as preinstalled options for order.

    Alternatively, Kirdy accepts laser signals broken out to the front panel and is suitable for use in driving external laser heads, including commercial or custom ECDLs (with additional piezo driver) or injection-locked Fabry-Perot diodes.

\section{Firmware and driver}

    1550 Kirdy features front panel Ethernet and USB-C. Either DFU or OpenOCD can be used to flash firmware; OpenOCD however requires a JTAG adapter.

    Using M-Labs firmware, communication with a host system is performed over Ethernet/TCP in the form of predefined JSON objects. A Python driver implementing these can be found in the Kirdy firmware repo, hosted at \url{https://git.m-labs.hk/M-Labs/kirdy/}, under \texttt{pykirdy/driver}. See inline documentation for descriptions of particular functions and implemented capabilities.

    This driver may be used directly or through the Kirdy GUI, hosted in the same repo. To start the GUI, run the file \texttt{pykirdy/kirdy\_qt.py}. Users familiar with the Nix package manager through ARTIQ or for other reasons may note that the root of the repository includes a \texttt{flake.nix} with an appropriate development shell (e.g. \texttt{nix develop}) including all dependencies.

    \begin{figure}[hbt!]
        \centering
        \includegraphics[width=\textwidth]{kirdy_gui.jpg}
        \caption{Kirdy driver GUI}
    \end{figure}

    To first connect to Kirdy, use the "Connect" button in the lower right corner and the IP address and port number assigned to Kirdy. By default, these are generally \texttt{192.168.1.128} and \texttt{1550} respectively; they can also be changed using commands supplied by the Python driver.

\ordersection{1550 Laser Diode Driver Kirdy}

    Kirdy can ship with single-frequency narrow-linewidth laser pre-mounted. Current options include 1270-1610nm and 633-1064nm. See hardware selection tool or contact M-Labs for prices and details.

\finalfootnote

\end{document}
