Laser Lock Box


Moku:Lab’s Laser Lock Box enables you to lock a laser’s frequency to a reference cavity or atomic transition using high-performance modulation locking techniques. The Laser Lock Box includes a ‘Tap‑to‑Lock’ feature, enabling you to quickly lock to any zero-crossing on the demodulated error signal. It also features an integrated 2‑channel oscilloscope, allowing you to observe signals at any point in the signal processing chain at up to 500 MSa/s.


If Moku:Lab only has two output channels, how is it possible to generate feedback control signals as well as the modulation tone and scanning waveform?

The low-bandwidth control signal on output Channel 2 can be separated electronically from the high-frequency modulation tone using an external bias-tee (not included with Moku:Lab). An appropriate bias-tee can be purchased from Mini-Circuits.

The scanning waveform is typically applied to the same actuator as the high-bandwidth control signal, so no bias-tee is required to separate the two signals.

Can I adjust the corner frequency of the low-pass filter?

Yes! The low-pass filter corner frequency can be tuned from 1 kHz to 14 MHz. You can also select different filter types including Chebyshev II and Elliptic filters that can be used to notch troublesome resonances.

What laser locking techniques does the Laser Lock Box support?

The Laser Lock Box supports a number of different locking techniques including Pound-Drever Hall (PDH) locking, Heterodyne offset phase locking, RF locking and Dither locking.

Does it lock continuous wave and pulsed lasers?

The Laser Lock Box can be used to stabilize the frequency of continuous wave lasers.

What if my actuator can’t take negative voltages?

The Laser Lock Box has output voltage limiters designed for exactly this purpose. You can set arbitrary high and low limits on each output and the control signals will be clamped to these levels, preventing damage to sensitive actuators. Note that the modulation signal from the auxiliary oscillator is not clamped to avoid clipping and distortion.

When and how should I use the slow PID controller?

When stabilizing lasers, there are often multiple actuators to feed back to. A common situation is to have one fast actuator with limited range (e.g. current or piezo) and one slow actuator with a much larger range (e.g. temperature). The slow PID controller acts on the fast PID controller’s output, keeping it centered around zero and thus maximizing the dynamic range for fast feedback.