Reset-Free Polarization Tracker – PolaStay™
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GP-DS-POS-002-20 1/5/10 The PolaStay™ polarization tracker automatically adjusts the state of polarization (SOP) towards a reference SOP, counteracting continuous input SOP variations as fast as 0.7 ms with no resets. The reference SOP is determined by a feedback signal which can be provided either internally or externally. The internal feedback version (POS-002-I) consists of a fiber squeezer polarization controller, in-line polarization monitor, digital and analog circuits, and proprietary algorithm. The error signal from the polarization monitor is fed back to the polarization controller to maintain a linear SOP at the output. The external feedback version (POS-002-E) replaces the internal polarization monitor with an external analog electrical feedback signal of the user’s choice, such as a voltage proportional to the degree of polarization (DOP) measured by a polarimeter, the bit-error rate (BER) from a BER chip, the RF spectrum of a detected signal, or the optical power after a polarizer. The output fiber can be either single mode fiber or PM fiber with the SOP aligned to its slow axis. This module can be used for PMD compensation, polarization division demultiplexing, elimination of polarization fading in coherent detection and fiber sensor systems, suppression of noise figure in optical amplifiers, and reduction of PDL effects. General Photonics Corp. 5228 Edison Ave. Chino, CA 91710 Tel: 909.590.5473 Fax: 909.902.5536 Email: info@generalphotonics.com Website: www.generalphotonics.com Reset-Free Polarization Tracker –PolaStay™ POS-002 Operating Wavelength Range1 1260 to 1650 nm SOP recovery time < 2 ms (0.7 ms typical) SOP rotation tracking speed (reset free) 47ð/s SOP accuracy2 < 0.1 dB Repeatability2 < 0.1 dB Insertion loss 0.8 dB typical, 1.2 dB max. Return loss > 50 dB Isolation in orthogonal polarization 20 dB Optical input power -15 dBm to 20 dBm standard for internal feedback version (low power option available) External feedback voltage 0 to 4.6 volts for external feedback version Optical Power Handling 20 dBm max., higher possible Optical Power Damage Threshold 300 mW Operating Temperature 0 to 70°C Storage Temperature -20 ~ 70 °C Power Supply +12 VDC / 0.5A -12VDC / 0.15A Communications Interface RS-2323 Dimensions 0.75”(H) x 3.8” (W) x 7.25” (L) Notes: Specifications listed above are for the standard configuration with internal feedback option; specs may be different for instruments with different wavelength or input power ranges. 1. Wavelength range listed is for standard version with SM output. Wavelength ranges will be different for versions with PM output. Applications: PMD compensation Polarization demultiplexing Elimination of polarization fading Coherent detection Ordering Information: POS – 002 – X -- XX Unique Features: Reset free operation 0.7 ms recovery time 47ð/s tracking speed Plug and play Feedback I: Internal E: External Preliminary Specifications Output fiber type: SM PM 2. The output power fluctuation caused by SOP fluctuation after passing through a polarizer. 3. Requires a special cable (included).

Typical Performance Data: Figure 1. PolaStay™ polarization tracker function diagram. Either internal or external feedback can be used. Figure 2 POS-002-I compensation for a step polarization change. 012345678010255010012515020025050075010001250150017502000Polarization Modulation Frequency (Hz)Power Penalty (dB)4090180 Figure 3. POS-002-I tracking of sinusoidal polarization modulation. Figure 4. POS-002-I tracking of half-wave plate rotation at 45ð rad/s. Input signal with step polarization change Driving electronics A/D Electronics Power supply D/A ì-processor Control Algorithm Polarization...

Application examples PMD compensation GP-DS-POS-002-20 1/5/10 Scheme 1: Using a polarimeter to obtain feedback signal. In this scheme, a polarimeter is used to detect the degree of polarization (DOP) of the signal to indicate the PMD effect on the signal. The DOP will be maximized when the PMD is properly compensated. The user constructs a simple circuit to convert DOP into an analog signal between 0~5V and feeds this signal back to the POS-002-E. The polarization tracker then automatically maximizes DOP to achieve PMD compensation. Scheme 2: Using the receiver to obtain the feedback...

PBS GP-DS-POS-002-20 1/5/10 feedback signal to effectively separate the two polarization channels. Scheme 2: BER detection. The bit-error rate (BER) before the forward error correction (FEC) in the receiver is detected as the error signal for polarization demultiplexing. The BER will be minimized when the two polarization channels are properly separated. A simple circuit can be used to convert the BER into a 0~5V feedback signal for the POS-002-E: the bigger the voltage, the smaller the BER. The polarization tracker then automatically maximizes the feedback signal to effectively separate...

Coherence detection GP-DS-POS-002-20 1/5/10 In a coherent detection system, the states of polarization of the signal and local oscillator must be the same in order m transmission fiber. The SOP of the output of the polarization tracker is linear and aligned with the slow axis of the PM fiber pigtail and will beat with the local oscillator. P P monitored with a phase modulator and can be converted into an analog signal of 0-5 volts to be fed back to the POS-002-E. The polarization tracker then automatically maximizes the visibility for stable, optimized detection sensitivity. SM TX DPSK RX...