untitled

Size: px

Start display at page:

Download "untitled"

ゆりかふじがわ
5 years ago
Views:

1 - i -

2 - i -

3 Application of All-Optical Switching by Optical Fiber Grating Coupler Yasuhiko Maeda Abstract All-optical switching devices are strongly required for fast signal processing in future optical communication systems. In this report, all-optical switching operations at the wavelength region of the 1.55µm utilizing the optical fiber nonlinearity in an optical fiber grating coupler (FGC) are reported theoretically and experimentally. These results indicate the possibility of applying all-optical switching devices with pico-second operation. The FGC, which is an optical fiber coupler (FC) with a refractive index grating in the coupling region, has been proposed as add/drop multiplexers (ADM) in wavelength division multiplexing (WDM) systems. This grating structure creates a narrow photonic band gap and results in reflection with a sharp spectrum at the Bragg wavelength. In order to route the signal, an all-optical switch which has two output ports and one input port is considered. A signal light is coupled by means of the FGC to a high power mode lock Ti-sapphire laser emitting at 800 nm as a pump light. The repetition frequency of the pump pulse is 80MHz, and the pulse width is 1.2ps. The wavelength characteristics, which depend on refractive effective index of gratings, can be altered by the high intensity pump pulse by increasing the effective index based on the Kerr effect. As a result, the incident optical signal can be switched between two output ports by means of an optical controlling. In this study, the reflected wavelength spectra detuning of the incident pump pulse in the nonlinear switching and switching characteristics are calculated using on the coupling equations including Kerr effect. The calculated results show that the nonlinear effect causes to increase the central wavelength of the FGC. The pump power to obtain switching operation is estimated to approximately 3kW at maximum depending on both grating length and pump pulse width. These results indicate the possibility of applying all optical switching devices in pico-second order. In addition, the switching experiments are carried out using an optical sampling oscilloscope to detect switched signal. As a result, the temporal switching waveform could not be observed due to noise. However, the results indicate that it might make possible observation of the temporal switching waveform by improving the experimental setup. The theoretical and experimental result of this research would be useful for the designs of all-optical high speed switching devices. Keyword: All optical switching, Optical fiber grating coupler, pico-second, Ti-sapphire laser, Kerr effect - ii -

4 iii -

5 iv -

6 - 1 -

7 - 2 -

8 - 3 -

9 - 4 -

10 Beam splitter UV laser beam UV laser beam Mirror Mirror Phase grating mask Optical fiber Optical fiber λ B λ λ B Λ 500m n eff+ n n eff - 5 -

11 Gratings Λ n n 2 Port 4 Port 3 Port 1 B = 2 Port 2 λ 1 λ 2 λ Optical coupler λ 1 λ 3-6 -

12 β 2 β 1 θ 1 θ 2 n λ sinθ 2 = ncore sinθ + m Λ core 1 n eff 1 = n core sinθ 1 n eff 2 = n core sinθ 2 2π β 1 = n eff 1 λ 2π β 2 = n eff 2 λ - 7 -

13 2π β 2 = β1 + m Λ n eff 1 n = neff 2 neff + 2 β, β 1 2 β = 2 β 1 n neff Λ λbm = 2 m λ 2n Λ B = eff - 8 -

14 2π n( z) = neff + n( z)[1 + cos{ z + φ( z)}] Λ u(0) v(0) n eff n eff + n u(l) v(l) Uniform grating in optical fiber Λ z 0 L - 9 -

15 = ) ( ) ( ) ( ) ( z v z u e e j z v z u dz d jkz jkz β κ κ β Λ = π 2 K λ η π κ n eff = V = η jkz e ) ( ), ( z V z U = ) ( ) ( 0 0 ) ( ) ( 2 / 2 / z v z u e e z V z U jkz jkz = ) ( ) ( ) ( ) ( 2 / / ) ( ) ( z V z U j z V z U jk jk z V z U dz d β κ κ β = ) ( ) ( ) ( ) ( z V z U j z V z U dz d δ κ κ δ 2 K = β δ

16 z = 0, z = L U (0) = V (0) coshγl + U ( L) V ( L) [ M ] m m γ γ [ M ] = = δ j sinh γl κ j sinh γl γ κ j sinh γl δ coshγl j sinh γl γ 21 m m 22 γ 2 2 = κ δ * m 22 = m 11 * m 21 = m = m m 1 r t U ( 0) 0, V ( L) = 0 V ( 0) = ru (0) U ( L) = tu (0) m m 21 r =

17 1 t = m 11 2 T = t 2 2 R = r = 1 t R B πl nη = tanh 2 ( ) λ B 2 2 λ B 2 π nl λ = + B π 2 n π eff L λb θr ω 2 dθ p λ dθ p τ r = = dω 2πc dλ D p 2 dτ p 2πc d θ p = = 2 2 dλ λ dω

18 [M ] [M 2 ] [M N ] 0 L z L dz = N δ coshγ ( dz) + j sinh γ ( dz) U ( z) γ = * V ( z) κ j sinh γ ( dz) γ κ j sinh γ ( dz) γ U ( z + dz) = δ V ( z + dz) coshγ ( dz) j sinh γ ( dz) γ [ M ] [ M ] [ M ] [ ] = 2 M N

19 - 14 -

20 - 15 -

21 ξ n t = n eff ( dn / dt ) / n = ξ n T eff eff dλ Λ t = Λ T = η Λ T Λ dt eff λ = 2 n Λ + 2n Λ B t eff t

22 Optical Power Meter Port4 Thermometer FGC GPIB Peltier device Tunable Diode Laser Port 1 Power[W] Wave length [nm]

23 Optical spectrum Analyzers Attenuator Port4 FGC Port3 A Lens20 Port1 Port2 Port1 Peltiert device Port2 CW Port4 Coupler Port3 LD Nd-YVO laser SHG Mirror 532nm Ti-sapphire laser nm Oscillo scope 85% 15% Autocorrelator Bare fiber connector A

24 Port 4 Port Port Port Fiber Coupler 780nm Port2 Port3 Port 30.7% Port Port % 1-2 Fiber Coupler 780nm Port2 Port3-19 -

25 Reflected Power [A.U.] FWHM 0.44nm Wave length [nm] λ B nm Power[A.U.] Wave length [nm]

26 LP mode Electric field[a.u.] LP01 Electric field[a.u] LP11 B=1554nm

27 - 22 -

28 n eff 2 = n + n I

29 - 24 -

30 Port 4 Port 3 Port B signal = B Port 1 B (1) Port 2 Port 4 Port 3 signal = B Pump B + B Port 1 (2) Port 2 (3)FGC

31 1 Uniform gratings Reflected power [A.U.] W 600W W 2kW λ [nm]

32 1 Relative switching [A.U.] nm Uniform gratings Port3 Port Pump peak power [kw] Gauss apodization gratings

33 Relative switching [A.U.] nm Gauss apodization gratings Port4 Port Pump peak power [kw] c L CP = TCP n eff

34 L CP n eff+ n n eff 1 Reflected W 1000W 2000W Uniform gratings Kerr effect 20% λ[nm]

35 Relative switching Port4 Port nm Uniform gratings Kerr effect 20% Pump peak power [kw] Relative itching Port4 Port nm Uniform gratings Kerr effect 20% Pump peak power [kw]

36 . Oscillo scope Two phase lock-in amplifier AMP. InGaAs PIN-P.D Port 4 FGC Port 3 Light chopper A Port 1 Port 2 Fiber Coupler Port 1 Port 2 (FC) Tunable diode laser Port 4 Port nm Optical power meter 800nm LD Nd-YVO Laser SHG 532nm Ti-sapphire laser 800nm Oscillo scope Autocorrelator Glass filter Lens20 mirror Bare fiber connector A

37 - 32 -

38 Reflected power [A.U.] Wavelength [nm]

39 1 Reflected power [A.U.] Wavelength λ[nm] Lock-inamp. output voltage [A.U.] Wavelength shift 0.05nm 0.1nm 0.2nm Wavelength λ[nm]

40 Refrected power [A.U.] Wavelength λ[nm] Lock-inamp.output voltage [A.U.] 500W 1.5kW 2kW Wavelength λ[nm]

41 Lock-in amp.output voltage [mv] W 879W 1080W 1438W Wavelength λ[nm] 12 Lock-in amp. output voltage [mv] nm nm nm Pump 800nm 1.2ps Pump peak power [W]

42 800nm Control Plus Light chopper. Oscillo scope Ti: sapphire laser Tunable diode laser Port 2 2-1Coupler Port 3 Port 1 Glass filter InGaAs PIN-P.D. AMP. Two phase lock-in amplifier 1540nm Signal Lens

43 Lock-in amp. Output voltage[v] 0.03 Light chipper frequency 280Hz Wavelength λ[nm] 0W 0.6kW 1kW 1.3kW 1.6kW 1.8kW 2.1kW

44 1540nm Signal Tunable Port 3 Diode 2-1 FC Port 1 Port 4 InGaAs FGC Port 3 PIN-P.D Port2 Si Port 2 AMP. 800nm Pump Port 1. Oscillo scope Two phase lock-in amplifier 4-21 FGC

45 nm nm

46 - 41 -

47 λ/4 L/2 L/2 Λ n n core Quarter wave phase shift

48 1 Reflected Power [A.U.] λ/4phase shiftfgc Normal FGC λ[nm]

49 Pump 800nm,1.2ps 3kW 2kW 1kW 0W Pump 800nm,1.2ps

50 - 45 -

51 - 46 -

52 - 47 -

53 - 48 -

54 - 49 -

55 - 50 -

56 - 51 -

57 - 52 -

58 - 53 -

Microsoft PowerPoint - 山形大高野send ppt [互換モード]

Microsoft PowerPoint - 山形大高野send ppt [互換モード] , 2012 10 SCOPE, 2012 10 2 CDMA OFDMA OFDM SCOPE, 2012 10 OFDM 0-20 Relative Optical Power [db] -40-60 10 Gbps NRZ BPSK-SSB 36dB -80-20 -10 0 10 20 Relative Frequency [GHz] SSB SSB OFDM SSB SSB OFDM OFDM