Integrated spectrographs in the era of ELTs

Transcription

1 Integrated spectrographs in the era of ELTs N. Blind Max-Planck Institut fur Extraterrestrische Physik (MPE; Garching, D.) IPAG seminar ! APE 1

2 Context: Extremely Large Telescopes... E-ELT 39m GMT 24m TMT 30m 2

3 ...and Extremely Large... instruments E-ELT 39m VLT 8m Bulk instruments: Instrument size D Detector size D 2 Total cost D 2 3

4 ...and Extremely Large... instruments E-ELT 39m VLT 8m VLT E-ELT cost ~ 1 VLT 4

5 ...and Extremely Large... instruments E-ELT 39m VLT 8m VLT Is astrophotonics part of the solution? E-ELT cost ~ 1 VLT 5

6 Outline The problem of optical etendue A quick overview of astrophotonics Groups of spectrometers & identified technologies Performance of integrated spectrographs A few E-ELT science cases Conclusions 6

7 Etendue, coupling and modicity Law of optics: Beam optical etendue SΩ is conserved Object solid angle Ω Ω ρ = Flux received by the spectrograph Flux collected by the telescope S Telescope aperture S Coupling efficiency ρ ~ max( SΩinstrument/SΩobject, 1) 7

8 Etendue, coupling and modicity Coupling efficiency ρ ~ max( SΩobject/SΩinstrument, 1) Ω Diffraction limit: SΩ ~ 1.2 λ 2 ELT+AO (NIR; S~0.3): SΩ > 100 λ 2 (85%EE) ELT+AO (VIS; S<0.01): SΩ >> 1000 λ 2 (85%EE) S Sω = SΩ/λ 2 Sω 8

9 Etendue, coupling and modicity Coupling efficiency ρ ~ max( SΩobject/SΩinstrument, 1) Ω Diffraction limit: SΩ ~ 1.2 λ 2 ELT+AO (Strehl~0.3): SΩ > 100 λ 2 Bulk optics: SΩ >> 1000 λ 2 Sω = SΩ/λ 2 S 9

10 Etendue, coupling and modicity Coupling efficiency ρ ~ max( SΩobject/SΩinstrument, 1) Ω Diffraction limit: SΩ ~ 1.2 λ 2 ELT+AO (Strehl~0.3): SΩ > 100 λ 2 Sω = SΩ/λ 2 SM waveguides: SΩ ~ λ 2 S Waveguides modes 10

11 Etendue, coupling and modicity Coupling efficiency ρ ~ max( SΩobject/SΩinstrument, 1) Ω Diffraction limit: SΩ ~ 1.2 λ 2 ELT+AO (Strehl~0.3): SΩ > 100 λ 2 Bulk optics: SΩ >> 1000 λ 2 SM waveguides: SΩ ~ λ 2 S Sω = SΩ/λ 2 ρsm, diffraction limit ~ 80% Waveguides modes 11

12 Etendue, coupling and modicity Coupling efficiency ρ ~ max( SΩobject/SΩinstrument, 1) Ω Diffraction limit: SΩ ~ 1.2 λ 2 ELT+AO (Strehl~0.3): SΩ > 100 λ 2 Bulk optics: SΩ >> 1000 λ 2 SM waveguides: SΩ ~ λ 2 S Sω = SΩ/λ 2 ρsm < 1% in NIR SM: low coupling efficiency Waveguides modes 12

13 Etendue, coupling and modicity Coupling efficiency ρ ~ max( SΩobject/SΩinstrument, 1) Ω Diffraction limit: SΩ ~ 1.2 λ 2 ELT+AO (Strehl~0.3): SΩ > 100 λ 2 Bulk optics: SΩ >> 1000 λ 2 SM waveguides: SΩ ~ λ 2 MM waveguides: SΩ > 50 λ 2 S Sω = SΩ/λ 2 ρmm > 50% MM spectrometers: spectral resolution < 2000 Waveguides modes 13

14 Etendue, coupling and modicity Coupling efficiency ρ ~ max( SΩobject/SΩinstrument, 1) Ω Diffraction limit: SΩ ~ 1.2 λ 2 ELT+AO (Strehl~0.3): SΩ > 100 λ 2 Bulk optics: SΩ >> 1000 λ 2 SM waveguides: SΩ ~ λ 2 MM waveguides: SΩ > 50 λ 2 M-SM waveguides: SΩ ~ Ng λ 2 S Sω = SΩ/λ 2 ρmsm ~ Ng ρsm M-SM (Multi Single Mode): device with several SM entries (e.g. SWIFTS) Waveguides modes 14

15 Etendue, coupling and modicity Coupling efficiency ρ ~ max( SΩobject/SΩinstrument, 1) Mode conversion Photonic lantern Ω Diffraction limit: SΩ ~ 1.2 λ 2 ELT+AO (Strehl~0.3): SΩ > 100 λ 2 SΩ ~ Ng λ 2 Bulk optics: SΩ >> 1000 λ 2 SM waveguides: SΩ ~ λ 2 MM waveguides: SΩ > 50 λ 2 M-SM waveguides: SΩ ~ Ng λ 2 MM Ng SM waveguides To S Sω = SΩ/λ 2 spectro(s) ρmsm ~ Ng ρsm M-SM (Multi Single Mode): device with several SM entries (e.g. SWIFTS) Waveguides modes 15

16 Astrophotonics: a quick overview Astrophotonics: use of photonic technos in astronomy Molding the flow of light (J. Bland-Hawthorn) Provide a set of integrated optical functions... 16

17 Astrophotonics: a quick overview Astrophotonics: use of photonic technos in astronomy Molding the flow of light (J. Bland-Hawthorn) Spectrographs [this talk] Complex filters: OH-line suppression Beam combiners/lboi PIONIER - GRAVITY AO/Pupil remapping: DRAGONFLY Detectors Phase/energy sensitive, etc. Spectral calibration Frequency Comb Lasers Efficient coupling: Photonic lantern 17

18 Astrophotonics: a quick overview Astrophotonics: use of photonic technos in astronomy Molding the flow of light (J. Bland-Hawthorn) Pros Compactness NIR Beam Combiner PIONIER & GRAVITY 18

19 Astrophotonics: a quick overview Astrophotonics: use of photonic technos in astronomy Molding the flow of light (J. Bland-Hawthorn) Pros Compactness Unique optical functions OH-line suppression AO/Pupil remapping: DRAGONFLY 19

20 Astrophotonics: a quick overview Astrophotonics: use of photonic technos in astronomy Molding the flow of light (J. Bland-Hawthorn) Pros Compactness Unique optical functions Cons SM/diffraction limited 20

21 Astrophotonics: a quick overview Astrophotonics: use of photonic technos in astronomy Molding the flow of light (J. Bland-Hawthorn) Pros Compactness Unique optical functions Cons SM/diffraction limited Photonic lantern Pixels Photonic lantern Efficient coupling by mode conversion In - MM Out - Multi-SM (MSM) 21

22 Astrophotonics: a quick overview Astrophotonics: use of photonic technos in astronomy Molding the flow of light (J. Bland-Hawthorn) Pros Compactness Unique optical functions Cons SM/diffraction limited Throughput 22

23 Astrophotonics: a quick overview Astrophotonics: use of photonic technos in astronomy Molding the flow of light (J. Bland-Hawthorn) Pros Compactness Unique optical functions Fully integrated instrument GNOSIS Ellis+, 2012, SPIE, 7351, PRAXIS Horton+, 2012, SPIE, 8450, 84501V PIMMS Bland Hawthorn+, 2010, SPIE, 7735, 77350N Mode conversion 23 Cons SM/diffraction limited Throughput Material Integrated Sky background filtering Spectrograph

24 Astrophotonics: a quick overview Astrophotonics: use of photonic technos in astronomy Molding the flow of light (J. Bland-Hawthorn) Pros Compactness Unique optical functions Fully integrated instrument Cons SM/diffraction limited Throughput Birefringent Material 24

25 Astrophotonics: a quick overview Astrophotonics: use of photonic technos in astronomy Molding the flow of light (J. Bland-Hawthorn) Pros Compactness Unique optical functions Fully integrated instrument Mass production capabilities Reduced costs Cons SM/diffraction limited Throughput Birefringent Unitary cost Mass prod. 25

26 Identified technologies Spectrum = FT of the signal autocorrelation (Wiener-Khintchine) = { delay + interferences } High resolution = long delay 26

27 Identified technologies Spectrum = FT of the signal autocorrelation (Wiener-Khintchine) = { delay + interferences } High resolution = long delay Medium/high resolution (R>2000) = SM One mode = one optical index mixing/stretching of spectra n0 RMM < ~ πΔn 27

28 Identified technologies Spectrum = FT of the signal autocorrelation (Wiener-Khintchine) = { delay + interferences } High resolution = long delay Medium/high resolution (R>2000) = SM Three groups of spectrometers: Dispersers Filters, Fabry-Perot (FP) Fourier Transform Spectrometers (FTS) 28

29 Identified technologies: Dispersers Spectrum = FT of the signal autocorrelation (Wiener-Khintchine) = { delay + interferences } Detector Grating Pros 1 pixel = 1 spectral channel low photon noise Cons Cross dispersion for HR compactness! >:( IFS not easy 29

30 Identified technologies: Dispersers Arrayed Waveguide Grating (AWG) Cvetojevic+, 2012, Opt. Express, 20,

31 Identified technologies: Dispersers Semi-integrated Compact Grating Grabarnik, S., 2007, Opt. Express, 15,

32 Identified technologies: Dispersers Side Holographic Disperser Avrutsky Avrutsky+ 2006, Applied Opt., 45, 7811; Bergner+, 2012, Proc. of SPIE, 8374, 32

33 Identified technologies: Dispersers Photonic Crystal Superprism Lupu+ 2004, Opt. Express, 12, 5690; Momeni+, 2009, Opt. Communications, 282,

34 Identified technologies: Filters/FP Spectrum = FT of the signal autocorrelation (Wiener-Khintchine) = { delay + interferences } T L Pros IFS easy Emission lines regions MM 34 Cons Most light reflected

35 Identified technologies: Filters Zig-Zag Spectrometer Murry & Lin, us Patent App. 10/029,058 35

36 Identified technologies: Filters MEMS-based Fabry-Perots Wolffenbuttel, 2005, Journal of Micromechanics and Microengineering, 15, S145 36

37 Identified technologies: Filters Plasmonic Photon Sorters Imaging Laux,+, 2008, Nature Photonics, 2,

38 Identified technologies: FTS Spectrum = FT of the signal autocorrelation (Wiener-Khintchine) = { delay + interferences } dl FT Pros IFS easy RV MSM Cons FT propagates all the photon noise to each spectral channel

39 Identified technologies: FTS Micro-SPOC Guerineau+, 2005, Optical Society of America, FThA4 39

40 Identified technologies: FTS SWIFTS Le Coarer+ 2007, Nature Photonics, 1, 473 Lippmann configuration Gabor configuration 40

41 Identified technologies: FTS LLIFTS Martin+, 2009, Opt. Lett., 34,

42 Identified technologies: FTS AMZI Florjanczyk+, 2007, Opt. Express, 15,

43 Performances Low coupling Disperser Filter/FP FTS SM O X O MSM O X O MM O O O Lots of pixels SΩ/λ 2 Spectral resolution <

44 Performances: vs band Coupling of 100% - Only perf. of Disp. vs Filter vs FTS Equivalent transmissions Cold instrument Warm instrument (IR) Disp FTS Disp FTS SNR FP SNR FP 0.1 N phot = 10 5 B g = 10 5 ph N phot = 10 7 B g = 10 5 ph Spectral channels Spectral channels Results independent of the band wrt background 44

45 Performances: vs SΩ & Nλ HII regions R > Stars Single band R>10000 Multi band R~2000 Small telescope ELT-IR 50% EE SNR N λ = 4 Sω = 10 Disp FTS FP 0 10 N λ = 4 Sω = 1000 Magnitude wrt background SM MSM MM 20 SNR N λ = 5316 Sω = 10 Disp FTS FP 0 10 N λ = 5316 Sω = 1000 Magnitude wrt background 20 ELT-VIS SNR Disp FTS FP SNR Disp FTS FP Magnitude wrt background Magnitude wrt background 45

46 Performance summary Sω FP & FTS TAURUS TIGER 100 EAGLE MM DISPERSER (MM; Bulk) 1000 MUSE (MM if R < 1500; Bulk) MEMS FP Micro-SPOC M-SM FTS SWIFTS HARPS 10 SM DISPERSER AWG - SHD 1 Emission lines Complex spectra 46 Nλ, FF

47 Performance summary Sω 1000 FP & FTS (MM; Bulk) MEMS FP TAURUS Micro-SPOC TIGER MUSE MM DISPERSER (MM if R < 1500; Bulk) EAGLE 100 Performance are not all, you need a scientific context... M-SM FTS SWIFTS HARPS 10 SM DISPERSER AWG - SHD 1 Emission lines Complex spectra Nλ, FF 47

48 E-ELT science cases Science Cases and Requirements for the ESO ELT Report of the ELT Science Working Group, m E-ELT m E-ELT

49 E-ELT science cases Example 1 - Highly multiplexed IFUs First light - High-z Galaxies (C4) EAGLE case SNR SM MSM MM N λ = 2999 Sω = 377 θ = 100 mas Disp FTS FP J-band Requirements Magnitude wrt background Tentative instrument Entrance optics 2.5mx2.5m MSM disp.: AWG, pixels!!! SM disp.: 10 4 AWG, ~ pix, expensive (?)... MSM FTS: 10 4 SWIFTS, pix MM disp.: 10 4 AWG, ~ pix, to deepen cm 5cm Matrix of SWIFTS

50 E-ELT science cases Example 2 - Single IFU Black holes and AGNs (G9) Requirements Tentative instrument Several bands/spectros Diffraction limit case Disp. dominate At least 10 to 90 MSM disp. per band (maybe 10 times more) We know how to do that in bulk... 50

51 E-ELT science cases Example 3 - Radial velocities Exo-earths research (S3); Universe in expansion (C2) Disperser: line displacement FTS: fringe stretching FTS & dispersers of equivalent performance... Mosser+, 2003, PASP, 115(810), 990; Wang+, ApJ, 738:132 HARPS/ESPRESSO in a shoe box would be possible? 51

52 Conclusion ELTs need ELInstruments and ELBudgets Astrophotonics paves the way to a new generation of compact, stable, low cost (?) instruments Original functions allowed and already validated, lots to think about... Concerning integrated spectrographs: Developments to continue: bandwidth, throughput, MM instruments, etc. Now: interest for highly multiplexed IFUs on small telescopes? RV? 52

53 Thanks for your attention! 53