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Mode lockers

Mode Lockers (AOML)

Acousto-optic mode lockers (AOML) modulate the loss within a laser cavity at its resonant frequency, effectively “locking” the phase of the longitudinal modes to generate very narrow laser pulses of high intensity.

Our mode lockers for Nd:YAG, Nd:YLF, Ti:Sapphire and Argon Ion lasers can modulate at up to 200 MHz, yielding near-theoretical mode locked laser pulse widths. We offer antireflection (AR) coated and Brewster angle options. We design customized one-off mode lockers for demanding scientific and OEM applications.

An acousto-optic mode locker (AOML) is a specialized modulator operating within the laser cavity to actively control the loss and induce a fixed-phase relationship between multiple longitudinal modes of the laser cavity. The loss it introduces may be very small, but it need only be enough to preferentially select specific modes.

The number of active modes of a laser will depend both on its gain medium and on the cavity length, but they may not be in phase. A mode locker operating at a frequency synchronized with the round trip time of the laser cavity will allow only those modes which are in phase to build up and interfere constructively, thus generating high intensity pulses at a well-defined repetition rate. To achieve mode locking, the laser cavity mode spacing frequency (length) must be equal to twice the acoustic frequency of the mode locker. Our standard mode lockers include operating frequencies from 38 MHz to 80 MHz.

The more modes that are locked together in phase, the shorter the pulse. Our standing wave mode lockers can obtain near theoretical mode locked laser pulse widths, with industry-leading transmission performance. Our AO device design experience coupled with strict manufacturing controls enable us to deliver high-Q (very low loss) mode lockers with minimal extraneous modes.  

Our high-Q mode lockers can be used for Nd:YAG, Nd:YLF, Ti:Sapphire and Argon ion lasers at near infrared wavelengths to achieve picosecond and femtosecond length pulses at repetition rates of up to 200 MHz. The short pulses generated are often used in applications like nonlinear optics, optical data storage, femtosecond micromachining, and multiphoton microscopy.  

High repetition rates are often desired for scientific applications, including those using optical heterodyne detection for spectroscopy, LIDAR or telecommunications.  

RF driver selection impacts mode locking system performance. Active temperature control of the acoustic resonator can assist in controlling resonant frequency such that resonance at the precise frequency of the driver's oscillator can be maintained. We can assist choosing the right driver for your application. We can help explain which aspects of each RF driver influence mode locking efficiency and pulse width. 

Our acousto-optic mode lockers are manufactured using high quality fused silica, polished and fabricated in-house to ensure high quality and reliability. We achieve >99% transmission at 1064 nm by using a durable in-house antireflection V-coat. For transmission over a broader range of wavelengths (700-1100 nm) we recommend using windows cut to the Brewster angle. Low scatter and tight quality controls ensure that every mode locker is capable of handling high peak laser power over the long term without damage. 

From custom wavelengths to high repetition rates, we offer a wide range of standard and custom options for high performance, high-reliability mode lockers to achieve the shortest, most intense pulses possible.  

Applications of mode lockers

Femtosecond micromachining, fs/ps lasers (Nd:YAG, Nd:YLF,
Ti:Sapphire, Argon ion), LIDAR, multiphoton microscopy, nonlinear optics, optical data storage, optical heterodyne detection for spectroscopy, telecommunications

ProductTypeWavelengthOperating FrequencyActive ApertureWindow TypeOptical Material