Mach-Zehnder Type Interferometer
- OCT-Proven Clock for Swept Source Systems
- Compact Design that Allows Subassembly Integration
- Several Wavelengths Available
|INT-MZI-850||780 - 925 nm||Si/PIN||103.3 GHz ± 5%||<1.5 dB (Typ.),
3 dB (Max)
|INT-MZI-1300||1225 - 1375 nm||InGaAs/PIN||<0.7 dB (Typ.),
1 dB (Max)
- For 850 nm or 1300 nm Center Wavelengths
- Ideal for Swept Source Output Frequency Monitoring
- Balanced Detection Output
- Low Insertion Loss: <3 dB
- Flat Wavelength Response
- Integrated Signal Detection for Power Monitor and k-Clock Signals
- Interferometer Power Supply Included
Thorlabs' Mach-Zehnder interferometer clock box subassemblies are designed to be used inside a swept source OCT system with a central wavelength of either 850 nm or 1300 nm. The internal fiber couplers are optimized for flat wavelength responses and coupling losses that have a very low polarization dependence, which make the output signals independent of input polarization changes. The clock box contains two detectors, providing a power monitor signal and a k-clock signal that monitors the output frequency of the swept source. Both outputs have a 200 MHz bandwidth, and the k-clock uses a balanced detection scheme to maximize rejection of common mode noise.
Although originally designed for OCT systems, this clock can also be used for other synchronization applications.
For more details on the clock, please see the Operating Principles Tab.
Note: Custom models are available with a choice of free spectral range and wavelength. Please contact Tech Support for more information.
|Interferometer Wavelength Range||780 - 925 nm||1225 - 1375 nm|
|Free Spectral Range||103.3 GHz ±5%||103.3 GHz ±5%|
|Fiber Type||Nufern 780-HP™||Corning SMF28™|
|Input/Output Connection||FC/APC Pigtail, 50 cm Long|
|Insertion Lossa||<1.5 dB (Typ.), 3 dB (Max)||<0.7 dB (Typ.), 1 dB (Max)|
|Detector Wavelength Range||320 - 1000 nm||800 - 1700 nm|
|Typical Responsivity (Max)||0.53 A/W||1.0 A/W|
|MZI Output Bandwidth (3dB)||DC - 200 MHz|
|Conversion Gain Power Monitorb||30 V/W (±25%)||60 V/W (±25%)|
|Conversion Gain MZI Outputb||±30 V/W (±25%)||±60 V/W (±25%)|
|Saturation Power||100 mW @ 850 nm||50 mW @ 1300 nm|
|Maximum Input Power||250 mW (Photodiode Damage Threshold)|
|DC Offset||< ±5 mV|
|Power Supply||±12 V @ 250 mA
(100/120/230 VAC, 50 - 60 Hz, Switchable)
|Dimensions||120 mm x 80 mm x 16 mm|
Rapidly swept laser sources typically use sinusoidal tuning elements to achieve the very fast optical frequency sweep speeds required for OCT imaging applications. Hence, accurate and reliable re-calibration of the OCT signal is required so that the final data points are equidistant in frequency. The Thorlabs swept source laser features a built-in Mach-Zehnder Interferometer (MZI) with balanced detector output that can be used for just this purpose. A frequency clock is derived from the zero crossings of the MZI interference fringe signal; these zero crossings are equally spaced in optical frequency (k-space). While this clock is intended for OCT applications, it can also be used in other synchronization applications.
Figure 1: MZI Clock Signal
The schematic of the system is shown in figure 2 below. An internally fiber network is used to tap 5% of the input light to generate Power Monitor and k-clock signals. The remaining light is transmitted to the Output pigtail. Specially designed couplers are used to achieve a flat wavelength response for both the transmitted and the Power Monitor signal. (see figures 3 and 4 below). Both signals of the MZI are detected by an ultra-low noise amplified balanced photo detector.
Figure 2: Schematic of MZI Series Clock Box
Figure 3: Coupling Ratio for INT-MZI-1300 from Input to Output
Figure 4: Coupling Ratio for INT-MZI-1300 from Input to Power Monitor
Power Monitor Output
0 - 1.8 V (50 Ω) or 0 - 3.6 V (High Z)
Mach-Zehnder Interferometer Output
0 - 1.8 V (50 Ω) or 0 - 3.6 V (High Z)