Electro-optic Modulators

STK Series EO Light Modulators and Drivers

List of EO Modulators & Drivers

• Phase Modulator

• Intensity Modulator

• Driver

1. Electro-optic Intensity Modulator

The STK-AM series electro-optic intensity modulator utilizes the electro-optical effect of lithium niobate and push-pull Mach-Zehnder interference structure to achieve intensity modulation of optical signals. It features low insertion loss, high modulation bandwidth, high extinction ratio, low half-wave voltage and high damage optical power. This product is mainly used for electro-optical signal conversion in high-speed optical fiber communication systems, the generation of light sidebands, high extinction ratio light pulse generation in quantum communication, microwave fiber link and other fields.

Key Features

• Wavelengths optional

• Low half-wave voltage

• High bandwidth

• Low insertion loss

Applications

• High-speed optical fiber communication systems

• Microwave fiber link

• Quantum communication

1.1 1064nm High Extinction Ratio Electro-optic Intensity Modulator STK-AM-10

Key Features

• 1064nm Operation

• Low insertion loss

• 3dB bandwidth 5GHz

• Low half-wave voltage

• High Extinction Ratio >50dB

Applications

• Optical Pulse Generation

• Optical fiber sensing system

• Laser mode locking

The 1064nm high extinction ratio electro-optical intensity modulator integrates two Mach-Zehnder intensity modulators with a push-pull structure, which can achieve an extinction ratio of up to 50dB. It is used in the fields of high-speed optical pulse generation, fiber sensing, and laser mode locking.

Block diagram

*with connector

Absolute Maximum Ratings

Ordering Information

• STK-AM-10-BW-PP-FA/FP-HER

• WL—Wavelength: 10-1064nm

• BW—Bandwidth: 5G---5GHz

• FA/FP—Connector: FA---FC/APC; FP---FC/PC

1.2 1550nm High Extinction Ratio Electro-optic Intensity Modulator

Key Features

• C and L-Band Operation

• Low insertion loss

• 3dB bandwidth 10GHz

• Extinction ratio 35/40dB

• Low half-wave voltage

• Integrated Monitor Photodiode

• Telecordia GR-468-CORE

Applications

• Microwave fiber link

• Quantum communication

• Optical pulse generation

• Optical fiber sensing system

• Laser mode locking

The 1550nm High Extinction Ratio LiNbO3 electro-optical intensity modulator based on the M-Z push-pull structure has a low half-wave voltage and stable physical and chemical characteristics, and the device has a high response rate, high extinction ratio(>40dB) and is therefore widely used in microwave fiber link, Quantum communication, optical Q-switched systems, laser mode-locking, and fiber sensing .

Schematic diagram

Absolute Maximum Ratings

Characteristic Curve

Ordering Information: STK-AM-WL-BW-PP-FA/FP-ER

• WL—Wavelength：15-1550nm

• BW—Bandwidth：10G---10GHz 20G-20GHz

• FA/FP—Connector：FA---FC/APC; FP---FC/PC

• ER----Extinction Ratio: 35dB, 40dB

1.3 10GB 1550nm All-in-one Electro-optic Modulator STK-MU-15-NRZ

We can provide with the driver for the above electro-modulators and integrate the modulator, amplifier and relevant controllers together. The user can manually or automatically set the bias points. At the manual setting mode, the bias can be displayed and the EO modulator and amplifier individually operate. At the automatic setting mode, the user can set various bias points according to the demand and the bias point is locked and displayed. The modulation performance of the modulator is not influenced by external factors such as environment temperature and vibration.

Ordering Information: STK-MU-W-XX-BW-FB-YY-M/A

• W: wavelength such as 15-1550nm, 13-1310nm, 10-1064nm

• XX: modulation method such as NRZ, DPSK, DQPSK, DPQPSK, AN, PM

• BW: bandwidth such as 02-2.5G, 10-10G, 20-20G, 40-40G

• FB: input/output fiber type such as PP (input & output are PM), PS (input is PM and output is SM)

• YY: fiber connector such as FA-FC/APC, FP-FC/PC

• M/A: control mode, M is manual and A is automatic.

2. Electro-optic Phase Modulator

The STK-KY-PM series electro-optic phase modulator utilizes the electro-optical effect of lithium niobate to achieve phase modulation of optical signals, and uses titanium diffusion or proton exchange process to fabricate optical waveguides, which can achieve dual-polarization or single-polarization phase modulation. It has low insertion loss, high modulation bandwidth, low half-wave voltage, high damage optical power, etc. This product is mainly used for optical chirp control in high-speed optical communication systems, phase delay in coherent communication systems, the generation of optical sidebands, phase modulation in quantum communication, reducing stimulated Brillouin scattering (SBS) in analog optical fiber communication systems and other fields.

Key Features

• Wavelengths optional

• Low half-wave voltage

• Low insertion loss

• High damage optical power

Applications

• Optical fiber sensing systems

• Optical fiber communication

• Laser coherent synthesis

• Phase delay (movement)

• Quantum communication

2.1 1550nm Optical CS-SSB Modulation Modules

The STK-MU-SSB-15 series product is an optical CS-SSB modulation module developed by our company. The modulation module integrates Mach-Zehnder dual parallel modulators, bias point control circuits, 90 degree hybrid splitter, can achieve stable and reliable single sideband modulation, and can switch between left and right sideband control as needed. This product is mainly used in Brillouin fiber sensing systems, microwave photonics, gas detection and other fields.

Key Features

• Wavelength C-band

• Sideband suppression ratio:>30dB

• Carrier suppression ratio: >26dB

• Up and down sidebands

• Convenient to use and reliable

Applications

• Optical fiber sensing system

• Microwave photonics

• Gas detection

• Optical fiber communication systems

3. Drive Module for Electro-optic Modulator

Key Features

• 10G, 20G, 40GHz optional bandwidth

• Gain> 25dB

• Saturated output Max.25dBm (11Vpp)

• Rise time Min.<8ps

• Low jitter

• DC12V power supply

• Easy to use

Applications

• High-speed optical fiber communication system

• Quantum communication

• Picosecond pulse amplification

• Optical fiber sensing system

Product List

• 10G driver module

• 10G high output driver module

• 20G driver module

• 40G driver module

The STK-KY-MD-XX series electro-optic modulator driver is a broadband, high-output driver amplifier mainly used for lithium niobate electro-optical intensity and phase modulator. Its working bandwidth is up to 30K ~ 40GHz, and it can achieve a maximum of 42Gbps NRZ wideband signal amplification up to 8Vpp. It is mainly used in high-speed optical fiber communication systems, quantum communication, picosecond pulse amplification, and optical fiber sensing systems.

Absolute Maximum Ratings

Characteristic Curve

Typical Application

SCQ Series Electro-optic Light Modulators

SCQ series electro-optic modulators have the features of low insertion loss, wide bandwidth, low half-wave voltage etc and are to be used in space optical communication, time base, pulse generator and quantum optics etc. 

SCQ series electro-optic modulators are mainly divided into two groups: intensity modulators and phase modulators. Their working wavelengths are 780nm, 850nm, 1064nm, 1310nm, 1550nm and 2000nm。Other wavelengths are available upon request. 

Definition of Part Numbers: SCQ-XX-WW-XG-F-FC

• XX: modulator type. AM is intensity modulator and PM is phase modulator.

• WW: operation wavelength, such as 850nm, 1064nm, 1310nm,1550nm and 2000nm

• XG: operation bandwidth, such as 2.5G, 10G, 40G

• F: In-out fiber such as PP (PM/PMF)

• FC: fiber connector such as FA (FC/APC), FP (FC/PC) 

1. SCQ Series Intensity Modulators 

1.1 SCQ-AM-1310 Series 1310nm Intensity Modulators

The LiNbO3 intensity modulator is widely used in high-speed optical communication system, laser sensing and ROF systems because of well electro-optic effect. The SCQ-AM series based on MZ structure and X-cut design, has stable physical and chemical characteristics, which can be applied both in laboratory experiments and industrial systems.

Features:

• Low insertion loss

• Bandwidth: 2.5GHz

• Low half-wave voltage

• Customization option

Applications:

• ROF systems

• Quantum key distribution

• Laser sensing systems

• Side-band modulation 

Optical Parameters:

Electrical Parameters:

Limit Conditions:

Order Information:

2. SCQ Series Phase Modulators

2.1 SCQ-PM Series 1310nm Electro-optical Phase Modulators

The LiNbO3 phase modulator is widely used in a high-speed optical communication system, laser sensing, and ROF systems because of well electro-optic effect. The SCQ-PM-1310 series, based on Ti-diffused technology, has stable physical and chemical characteristics, which can meet most applications in laboratory experiments and industrial systems.

Features:

• Low insertion loss

• Polarization-maintaining

• Low half-wave voltage

• Dual-polarization option

Application:

• Optical communication

• Quantum key distribution

• Frequency shifting 

Optical parameters:

Electrical Parameters:

Limit parameters:

Ordering Information:

3. Drivers

3.1  SCQ-RF Series Drivers

SCQ-RF broadband RF amplifier (or called as driver) is a desktop instrument specially designed for high-speed lithium niobate electro-optic modulator. This instrument can amplify the small high-speed signal level to the higher level that can drive the modulator, thus driving the lithium niobate (LiNbO3) electro-optic modulator to work, and has good gain flatness in the broadband range.

Features:

• High bandwidth: 10, 20 or 40 GHz

• Variable gain

• The output range is up to 8V

• Highly integrated

• Easy to use

Applications:

• 10/20/40G optical modulating system

• Fiber optic testing system

• Optical fiber sensing system 

Parameters of SCQ-RF-40 Driver

Limit Conditions

Eye Diagram

Ordering Information:

3.2 MZM Bias Controller 

The bias controller is specially designed for Mach-Zehnder modulators to ensure a stable operation state in various operating environments. Based on its fully digitized signal processing method, the controller can provide highly stable performance. The controller injects a low frequency, low amplitude dither signal together with bias voltage into the modulator. It keeps reading the output from the modulator and determines the condition of the bias voltage and the related error. A new bias voltage will be applied afterwards according to the previous measurement. In this way, the modulator is ensured to work under proper bias voltage.

Features:

• Bias voltage control on Peak/Null/Q+/Q−

• Bias voltage control on arbitrary point

• Ultra precise control: (1) 50dB  maximum extinction ratio on Null mode; (2) ±0.5◦ accuracy on Q+ and Q− modes

• Low dither amplitude: (1) 0.1% Vπ at NULL mode and PEAK mode; (2)  2% Vπ at Q+ mode and Q− mode

• High stability: with fully digital implementation

• Low profile: 40mm(W) × 30mm(D) × 10mm(H)

• Easy to use: (1) Manual operation with mini jumper; (2) Flexible OEM operations through MCU UART2

• Two different modes to provide bias voltage: (1) Automatic bias control; (2) User defined bias voltage

 Application:

• LiNbO3 and other MZ modulators

• Digital NRZ, RZ

• Pulse applications

• Brillouin scattering system and other optical sensors

• CATV Transmitter

Ordering Information

Part No.: SCQ-RF-BC

Remark: (1) The highest extinction ratio depends on and cannot exceed modulator maximum extinction ratio. (2) UART operation is only available on some version of the controller.

Performance:

Maxim DC Extinction Ratio:

In this experiment, no RF signals were applied to the system. Pure DC extinction has been measured.

(1) Figure 3 demonstrates the optical power of modulator output, when modulator controlled at Peak point. It shows 3.71dBm in the diagram.

(2) Figure 4 shows the optical power of modulator output, when modulator controlled at Null point. It shows -46.73dBm in the diagram. In real experiment, the value varies around -47dBm; and -46.73 is a stable value.

(3) Therefore, the stable DC extinction ratio measured is 50.4dB. 

Requirements for High Extinction Ratio:

(1) System modulator must have high extinction ratio. Characteristic of system modulator decides the maximum extinction ratio can be achieved.

(2) Polarization of modulator input light shall be taken care of. Modulators are sensitive to polarization. Proper polarization can improve extinction ratio over 10dB. In lab experiments, usually a polarization controller is needed.

(3) Proper bias controllers. In our DC extinction ratio experiment, 50.4dB extinction ratio has been achieved. While the datasheet of the modulator manufacture only lists 40dB. The reason of this improvement is that some modulators drift very fast. Our SCQ-RF-BC-ANY bias controllers update the bias voltage every 1 second to ensure fast track response.

Specifications:

1 MER refers to Modulator Extinction Ratio. The extinction ratio achieved is typically the extinction ratio of modulator specified in modulator datasheet.

2 CSO refers to composite second order. To measure CSO correctly, the linear quality of RF signal, modulators and receivers shall be

ensured. In addition, the system CSO readings may vary when running at different RF frequencies.

3 Please be noted that input optical power does not correspond to the optical power at selected bias point. It refers to the maximum optical power that the modulator can export to controller when bias voltage ranges from −Vπ to +Vπ . 

1 Some MZ modulators have internal photodiodes. Controller setup should be chosen between using controller’s photodiode or using modulator’s internal photodiode. It is recommended to use controller’s photodiode for lab experiments for two reasons. Firstly, controller photodiode has ensured quality. Secondly, it is easier to adjust the input light intensity. Note: If using modulator’s internal photodiode, please make sure that the output current of photodiode is strictly proportional to input power.

2 Polar pin is used to switch the control point between Peak and Null in Null control mode(determined by Mode Select pin) or Quad+ and Quad- in Quad control mode. If jumper of polar pin is not inserted, the control point will be Null in Null mode or Quad+ in Quad mode. Amplitude of RF system will also affect the control point. When there is no RF signal or RF signal amplitude is small, controller is able to lock the work point to correct point as selected by MS and PLR jumper. When the RF signal amplitude exceeds certain threshold, polar of the system will be changed, in this case, the PLR header should be in the opposite state, i.e. the jumper should be inserted if it is not or pulled out if it is inserted.

Typical Application: 

The controller is easy to use as follows:

Step1. Connect 1% port of the coupler to the photodiode of the controller.

Step2. Connect bias voltage output of the controller (through SMA or 2.54mm 2-pin header) to bias port of the modulator.

Step3. Provide controller with +15V and -15V DC voltages.

Step4. Reset the controller and it will start to work.

NOTE. Please be ensured that RF signal of the whole system is on before resetting the controller.