These resonant frequency high efficiency phase modulators incorporate a patent-pending design to achieve twice the modulation depth over our popular standard designs.

The high efficiency phase modulators are available in versions covering anywhere from 360 nm to 1600 nm.

The key to obtaining this pure phase modulation is good optical alignment of the beam to the crystal’s propagation axis and accurate orientation of the laser’s electric field with the crystal’s electro-optic axis. New Focus makes proper alignment easy, simply pass the beam through the mechanical apertures.

Maximizing the power transfer from a driver to an electro-optic crystal is the key to making efficient resonant modulators. For resonant bulk modulators this occurs only over a specific frequency range—when it is driven on or near its resonant frequency. We test the electrical performance of each bulk resonant modulator to ensure that the modulator is resonant at the specified frequency. In addition, our test procedure consists of measuring the modulator’s reflected power and quality factor, Q, using a scalar network analyzer. (The Q is a measure of the sharpness of the resonant circuit’s response.) Typically on resonance our modulators absorb more than 96% of the incident RF power. This is equivalent to a return loss of greater than 14 dB which is important for high modulation efficiency. In addition, with less than 4% of the incident RF power back-reflected, damage to the RF driver is prevented. Finally, we also test for the presence of acoustic vibrations, or piezo resonances. These piezo resonances occur primarily in the 1 to 20 MHz frequency range and can lead to unwanted amplitude modulation and beam deflection. If a piezo resonance is detected during testing, we can shift the modulator resonant frequency to minimize unwanted piezo effects.