This is a low voltage ADP transverse electro-optic modulator designed to operate at all wavelengths in the visible and is entirely free from piezo-electric resonances. This modulator has a high degree of temperature stability, but where long term d.c. amplitude is required it should be operated in a constant temperature environment. The modulation frequency is not limited by the device characteristics other than by its electrical capacitance and therefore depends on the drive circuit used. Wide band ar-coatings are used on all components.
This is a low voltage transverse KD*P electro-optic modulator designed to give maximum thermal stability beyond that obtained by the ADP type. Its transmission range is extended into the infra-red and its extinction ratio is also better than that obtained from its ADP counterpart. It does however display piezo-electric characteristics.
This is a low voltage transverse electro-optic modulator using high damage threshold lithium niobate. It has similar characteristics to the EM 200K with an optical range extended further into the infra-red.
Low voltage electro-optic light modulators specifications
|Model No.||EM 200A||EM 200K||EM 200L|
|Crystal Length||4 x 20mm||2 x 40mm||2 x 20mm|
|Half Wave Voltage at 633nm||220V||220V||220V|
|Wavelength Range||0.3 - 1.0?m||0.2 - 1.2?m||0.5 - 4.0?m|
|Max. Continuous Applied Voltage||250||250||400|
|Extinction ratio||> 100:1||> 200:1||> 200:1|
|Optical Transmission||> 85%||> 90%||> 90%|
All modulators are normally supplied Dry Nitrogen Filled.
For fixed frequency operation electro-optic phase modulators can be designed to operate up to at least 2 GHz.
By making the electro-optic crystal part of a tuned circuit, relatively low drive voltages can be used to achieve up to p radians of phase modulation. For the range 50 MHz to 1 GHz the optical element is made part of a lumped tuned circuit and above 1 GHz the optical element is made part of a re-entrant tuned cavity or the active component in a traveling wave system.
For the tuned circuit arrangements the drive power required from the source is usually less than one watt.
These phase modulators can currently only be supplied without a drive source.
General Specifications for electro-optic phase modulators
|1. PM50-500 (50 MHz to 500 MHz version)|
|Optical wavelength range||
600 - 1300 nm
Brewster cut or
ar/ar normal incidence rod
|RF Drive power||2 watt maximum for p radians|
|Tuning range of optical head||? 15% of center frequency|
|Voltage gain from tuned circuit||~ 100|
|Input impedance of head||~ 50 Ω|
|Note: These are typical specifications taken from a phase modulator operating at 100 MHz.|
|2. PM1000-2000 (1 - 2 GHz version)|
|Optical Wavelength range||
600 - 1300 nm
200 - 600 nm (ADP)
|Typical Crystal Configuration||15mm long, 2mm ?rod, ar/ar|
|Tuning range of cavity||? 5% of design frequency|
|Cavity Q||> 100|
|Cavity design impedance||~ 50Ω|
|Cavity overall dimensions||
50mm ?x 50mm length
(2 GHz version)
|Drive Power||0.5 - 2.5 watts|