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Virtually Imaged Phased Array (VIPA): Operation and Applications

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## Virtually Imaged Phased Array (VIPA): Operation and Applications

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**Virtually Imaged Phased Array (VIPA): Operation and**Applications Christopher Lin Avanex Corporation**Outline**• Background • Brief history • Virtually imaged phased array (VIPA) • Paraxial wave model • Applications • DWDM multiplexer/demultiplexer • Hyper-fine WDM • Chromatic dispersion compensator • Tunable dispersion compensator • Slope compensator • Tunable slope compensator • Coating variations • References**Brief History**• Invented by Dr. Masataka Shirasaki at Fujitsu Laboratories in 1996. • Licensed from Fujitsu Ltd. to Avanex Corporation to create a dual-supply base for commercialization in telecommunications applications. • Development abandoned by Avanex in 2001. • University research activity restarted in 2002 at Purdue University (Professor Andrew Weiner’s group).**Virtually imaged phased array (VIPA)**Etalon r = 100% Q r > 98% Virtual image array Collimated transmission 2t Input beam r = 0% M. Shirasaki, Optics Letters, vol. 21, no. 5, pp 366-368, 1996.**Virtually imaged phased array (VIPA)**ml/n f d 2t**t**R r Virtual Source Array Lens Axis F F Paraxial Wave Model (Air-spaced) FWHM FSR (Our derivation is also generalized to solid VIPAs, @IEEE JQE 40, pp. 420-426, 2004) S. Xiao, A. M. Weiner, C. Lin. CLEO2004.**Dispersion Law**Paraxial Approximation Pulse repetition period = 1 / FSR in VIPA direct space-to-time pulse shaping A very large angular dispersion for small incident angles, where the output angle balances the incident angle S. Xiao, A. M. Weiner, C. Lin. CLEO2004.**Comparison with a previous dispersion law**Plane wave theory based on geometrical light path analysis (A. Vega, A. M. Weiner, Appl. Opt., Vol. 42, No .20, Jul., 2003.) Paraxial expansion Plane wave theory Paraxial wave theory There is an obvious difference on the second order of the output angle! The second order dominates the dispersion under small incident angles! S. Xiao, A. M. Weiner, C. Lin. CLEO2004.**Dispersion at long beam focusing f = 300 mm**Plane wave theory Paraxial wave theory The incident angle is the only fitting parameter Circles data Paraxial wave Plane wave S. Xiao, A. M. Weiner, C. Lin. CLEO2004.**DWDM multiplexer/demultiplexer**Etalon Fiber array Collimating lens Optical fiber Focusing lens Line-focusing lens M. Shirasaki, Optics Letters, vol. 21, no. 5, pp 366, 1996.**HWDM**~3 GHz DWDM ~100 GHz Hyperfine WDM HWDM is a passivetechnology, and it can sub-multiplex DWDM to several GHz channel spacing. Novel optical spectral dispersers are crucial to HWDM. VIPA is a very promising candidate. Band X Current DWDM technology, based onBragg gratings, AWG, etc, typicallyoperates with hundreds or tens of GHz channel spacing. ( See also http://www.essexcorp.com/products.html) S. Xiao, A. M. Weiner, C. Lin. OFC2004.**HWDM Application**Radio frequency (RF) photonics 12.4-37.2 GHz RF waveforms generation by selecting and beating different longitudinal modes of a 12.4 GHz mode locked semiconductor laser through HWDM technology from Essex corp. (P. J. Delfyett, etc, IEEE PTL, 2002) Laser rate multiplication HWDM was used to select every fifth of the spectral modes from a 10 GHz mode locking laser to obtain a 50 GHz laser. (M. Currie, etc, Post Deadline, CLEO, 2003) Potential applications in optical communication 1. Increase flexibility for providing bandwidth granularity 2. Subcarrier multiplexing (SCM) for high speed optical communications 3. Mitigate the PMD by lower bit rate in HWDM channels while maintaining total bit rate 4. Low chromatic dispersion due to hyperfine channels. S. Xiao, A. M. Weiner, C. Lin. OFC2004.**Experiment Setup**VIPA 2 mm Translation ASE / TLS OSA / Power Meter F=180 mm Cylindrical Lens Spherical Lens SMF ASE: Amplified Spontaneous Emission SMF: SMF-28, 9/125 um TLS: Tunable Laser Source OSA: optical spectrum analyzer (10 pm resolution) ASE is used to demonstrate the multiple channel demultiplexing transmission spectra measured by OSA at different output angles. TLS with 1pm wavelength resolution is used to scan the filter lineshape, and the insertion loss is measured simultaneously. S. Xiao, A. M. Weiner, C. Lin. OFC2004.**Demultiplexing Channels**100 GHz FSR 1. A uniform shift of the fiber with a step of 0.16 degrees. 2. 3dB bandwidth: (1)OSA (10 pm resolution) 100 GHz17 pm 50 GHz 13 pm (2) TLS (1 pm resolution) 100GHz 12 pm 50 GHz 7 pm 50 GHz FSR S. Xiao, A. M. Weiner, C. Lin. OFC2004.**Uniform Channel Spacing**40 dB The step size is 300um (0.1 deg) and 450um (0.15 deg) for 20 pm and 30 pm channel spacing respectively, and the OSA has a 10 pm resolution. A 50 GHz solid VIPA is used. Uniform channel spacing with uniform angle spacing is demonstrated as constant angular dispersion can be obtained around zero output angle, S. Xiao, A. M. Weiner, C. Lin. OFC2004.**Chromatic dispersion compensator**Etalon Mirror Collimating lens Optical fiber Focusing lens Line-focusing lens M. Shirasaki, PTL, vol. 9, no. 12, pp 1598-1600, 1997.**Chromatic dispersion compensator**blue light travels more a f red light travels less c(y)**Cascaded VIPA Results**• L. D. Garret, A. H. Gnauck, M. H. Eiselt, R. W. Tkach, C. Yang, C. Mao, S. Cao. “Demonstration of virtually-imaged phased-array device for tunable dispersion compensation in 16x10 Gb/s WDM transmission over 480 km standard fiber.” Proceedings, OFC2000, PD7.**Tunable dispersion compensator**Etalon y Collimating lens x 3-d mirror Optical fiber Focusing lens Line-focusing lens**Tunable dispersion compensator**• 200 GHz etalon • Tuning range +/- 200 ps/nm • Bandwidth is measured at 1 dB from peak**Tunable 40 Gbps Results**• M. Shirasaki, Y. Kawahata, S. Cao, H. Ooi, N. Mitamura, H. Isono, G. Ishikawa, G. Barbarossa, C. Yang, C. Lin. “Variable Dispersion Compensator using the Virtually Imaged Phased Array (VIPA) for 40-Gbit/s WDM Transmission Systems.” Proceedings, ECOC2000, post-deadline paper.**Slope compensator**Etalon Collimator a I/O fiber b Line-focusing lens Diffraction grating Focusing lens 3-d mirror y x M. Shirasaki, S. Cao, OFC2001.**Tunable slope compensator**S. Cao, C. Lin, G. Barbarossa, C. Yang. IEEE/LEOS Summer Topicals Meeting, 2001.**a**b Rotatable diffraction grating S. Cao, C. Lin, G. Barbarossa, C. Yang. IEEE/LEOS Summer Topicals Meeting, 2001.**Dispersion offset**a l = 1545 nm b y x S. Cao, C. Lin, G. Barbarossa, C. Yang. IEEE/LEOS Summer Topicals Meeting, 2001.**Slope tuning**a b x y S. Cao, C. Lin, G. Barbarossa, C. Yang. IEEE/LEOS Summer Topicals Meeting, 2001.**Diffraction efficiency**S. Cao, C. Lin, G. Barbarossa, C. Yang. IEEE/LEOS Summer Topicals Meeting, 2001.**Diffraction efficiency**S. Cao, C. Lin, G. Barbarossa, C. Yang. IEEE/LEOS Summer Topicals Meeting, 2001.**Diffraction efficiency**S. Cao, C. Lin, G. Barbarossa, C. Yang. IEEE/LEOS Summer Topicals Meeting, 2001.**Tuning range**Characteristics of tunable slope compensator *This value is calculated. 80 km SMF28 = 6 ps/nm2 slope +/- 90 ps/nm dispersion error at edges of 30 nm band. S. Cao, C. Lin, G. Barbarossa, C. Yang. IEEE/LEOS Summer Topicals Meeting, 2001.**Tuning range**S. Cao, C. Lin, G. Barbarossa, C. Yang. IEEE/LEOS Summer Topicals Meeting, 2001.**(a)**(b) (c) Coating variations • Constant • Linear • Step C. Lin, M. Shirasaki. Photonics West, 2001.**Mode shapes**Arbitrary units mm C. Lin, M. Shirasaki. Photonics West, 2001.**Transmission spectra**dB nm (deviation from channel center) C. Lin, M. Shirasaki. Photonics West, 2001.**References**• DWDM and HWDM • M. Shirasaki. “Large angular dispersion by a virtually imaged phased array and its application to a wave-length demultiplexer.” Optics Letters, vol. 21, no. 5, pp 366, 1996. • S. Xiao, A. M. Weiner, C. Lin. “Demultiplexers with ~10 pm (1.25 GHz) –3dB transmission bandwidth using a virtually imaged phased array (VIPA).” Proceedings, OFC2004, TuL1. • S. Xiao, A. M. Weiner. “2-D wavelength demultiplexer with potential for >= 1000 channels in the C-band.” OSA Optics Express, vol. 12, pp 2895-2902, 2004. • S. Xiao, A. M. Weiner, C. Lin. “Experimental and theoretical study of hyperfine WDM demultiplexer performance using the virtually-imaged phased- array (VIPA).” Journal of Lightwave Technology, March 2005 (in press). • S. Xiao, A. M. Weiner. “8-channel hyperfine WDM demultiplexer using a virtually imaged phased array (VIPA).” IEEE Photonics Technology Letters, Feb. 2005 (in press). • Chromatic Dispersion Compensation • M. Shirasaki. “Chromatic-Dispersion Compensator Using Virtually Imaged Phased Array.” IEEE Photonics Technology Letters, vol. 9, no. 12, pp 1598, 1997. • M. Shirasaki, H. Isono, S. Cao. “Dispersion compensation using the virtually imaged phased array.” Proceedings, OECC1999, pp 1367-1370. • L. D. Garret, A. H. Gnauck, M. H. Eiselt, R. W. Tkach, C. Yang, C. Mao, S. Cao. “Demonstration of virtually-imaged phased-array device for tunable dispersion compensation in 16x10 Gb/s WDM transmission over 480 km standard fiber.” Proceedings, OFC2000, PD7. • M. Shirasaki, Y. Kawahata, S. Cao, H. Ooi, N. Mitamura, H. Isono, G. Ishikawa, G. Barbarossa, C. Yang, C. Lin. “Variable Dispersion Compensator using the Virtually Imaged Phased Array (VIPA) for 40-Gbit/s WDM Transmission Systems.” Proceedings, ECOC2000, post-deadline paper. • S. Cao, C. Lin, G. Barbarossa, C. Yang. “Dynamically tunable dispersion slope compensation using a virtually imaged phased array (VIPA).” Proceedings, IEEE/LEOS Summer Topicals Meeting 2001.**References**• VIPA Operation • M. Shirasaki, A. N. Akhter, C. Lin. “Virtually imaged phased array with graded reflectivity.” IEEE Photonics Technology Letters, vol. 11, no. 11, pp 1443, 1999. • C. Lin, M. Shirasaki. “Analysis of coating design in a virtually imaged phased array (VIPA) chromatic dispersion compensator.” Proceedings, Photonics West 2001. • S. Xiao, A. M. Weiner, C. Lin. “Spatial chirp effects in virtually-imaged phased-array wavelength demultiplexors.” Proceedings, CLEO/QELS 2003. • A. Vega, A. M. Weiner, C. Lin. “Generalized grating equation for virtually-imaged phased-array (VIPA) spectral dispersers.” Applied Optics, vol. 42, issue 20, p 4152-4155, 2003. • S. Xiao, A. M. Weiner, C. Lin. “A dispersion law for virtually imaged phased array spectral dipsersers based on paraxial wave theory.” IEEE Journal of Quantum Electronics, vol. 40, no. 4, pp 420-426, 2004. • S. Xiao, A. M. Weiner, C. Lin. “A dispersion law for virtually-imaged phased-array based on paraxial wave theory.” Proceedings, CLEO/QELS 2004, CThCC5. • Other Applications • S. Xiao, J. D. McKinney, A. M. Weiner. “Photonic microwave arbitrary waveform generation using a virtually-imaged phased-array (VIPA) direct space-to-time pulse shaper.” IEEE Photonics Technology Letters, vol. 16, no. 8, pp 1936-1938, 2004. • X. Wang, S. Xiao, A. M. Weiner. “High Resolution and High Speed Wavelength-Parallel Polarization Sensor for Dense WDM Systems.” Proceedings, OFC2005, ThH4 (accepted). • S. Xiao, J. D. McKinney, A. M. Weiner. “Photonic radio-frequency arbitrary waveform generation using a virtually-imaged phased-array (VIPA) direct space-to-time pulse shaper at 1.44 um.” Proceedings, CLEO/QELS 2004, CTuGG5.