⎇ⓥᵴേ ᡆૃࠬ࡯ࡄ࡯ࠦࡦ࠹ࠖ࠾ࡘ࠙ࡓశᵄࠍ↪޿ߚࠦࡅ࡯࡟ࡦ࠻ࠕࡦ࠴ࠬ ࠻࡯ࠢࠬ࡜ࡑࡦᢔੂ㗼ᓸಽశ Coherent anti-Stokes quasi-supercontinuum Raman scattering microscopic spectroscopy using ໊Ỉ⋥᮸㧔Naoki KARASAWA㧕 Tel & Fax: 0123-27-6063 E-mail: [email protected] Quasi-supercontinuum from a photonic crystal fiber was generated and used as a Stokes pulse in broadband coherent anti-Stokes Raman scattering (CARS) spectroscopy. The quasi-supercontinuum was created by modulating optical pulses by an acousto-optic modulator, and the group delays in the quasi-supercontinuum were compensated for by a pair of high index prisms. By the use of the quasi-supercontinuum, the CARS measurement time was reduced to be about one eighth compared with our previous study. With this setup, broadband CARS signals between 900 cm-1 and 3100 cm-1 of a single polystyrene bead sample have been measured successfully. ࠦࡅ࡯࡟ࡦ࠻ࠕࡦ࠴ࠬ࠻࡯ࠢࠬ࡜ࡑࡦᢔੂ㧔CARS㧕ಽశߪ⿥⍴శࡄ࡞ࠬ࡟࡯ࠩ࡯ࠍశḮ ߣߒߡ↪޿‫ࡊࡦࡐޔ‬శߣߘࠇߣᵄ㐳߇⇣ߥࠆࠬ࠻࡯ࠢࠬశࠍ↢૕ߥߤߩ⹜ᢱߦ㓸శߒ‫ߘޔ‬ ߩߣ߈⹜ᢱߩಽሶᝄേߦ౒㡆⊛ߦ⊒↢ߔࠆࠕࡦ ࠴ࠬ࠻࡯ࠢࠬశᵄࠍಽశߔࠆᣇᴺߢ޽ࠆ‫ޕ‬ᚒ‫ޘ‬ ߪࡈࠜ࠻࠾࠶ࠢ⚿᥏ࡈࠔࠗࡃ࡯㧔PCF㧕ߦ࠴࠲ ࡦࠨࡈࠔࠗࠕ࡟࡯ࠩ࡯߆ࠄߩశࡄ࡞ࠬࠍዉᵄߒ‫ޔ‬ ⊒↢ߔࠆၮᧄ࠰࡝࠻ࡦࡄ࡞ࠬࠍࠬ࠻࡯ࠢࠬశߣ ߒߡ↪޿ࠆᐢᏪၞ CARS 㗼ᓸಽశశቇ♽ߩ⹜૞ ࠍⴕߞߡ߈ߚ‫⎇ᧄޕ‬ⓥߢߪᓥ᧪ߩᚻᴺߦᲧߴ‫ޔ‬ ࠃࠅᒝᐲ߇ᐔမߢ᷹ቯᤨ㑆ߩ⍴❗߇ᦼᓙߐࠇࠆ ᡆૃࠬ࡯ࡄ࡯ࠦࡦ࠹ࠖ࠾ࡘ࠙ࡓశࠍ↪޿ߚᐢᏪ ၞ CARS ಽశታ㛎ࠍⴕߞߚ‫ޕ‬ Fig 1 The spectrum of quasi-supercontinuum (black curve) and the spectrum of a single fundamental soliton pulse (dashed curve). ታ㛎ߦ߅޿ߡߪ㖸㗀శቇ⚛ሶߦࠃࠅ PCF ߦ౉ ኿ߔࠆశᵄߩᒝᐲࠍ๟ᵄᢙ 500 KHz ߢᄌ⺞ߒ‫ޔ‬ ᡆૃࠬ࡯ࡄ࡯ࠦࡦ࠹ࠖ࠾ࡘ࠙ࡓࠍ⊒↢ߐߖߚ‫ޕ‬ Fig㧝ߦߘߩࠬࡍࠢ࠻࡞ࠍ␜ߔ‫ߚࠇߐ↢⊒ޕ‬ᡆ ૃࠬ࡯ࡄ࡯ࠦࡦ࠹ࠖ࠾ࡘ࠙ࡓߪᵄ㐳ߣㆃᑧᤨ 㑆ߩ⇣ߥࠆၮᧄ࠰࡝࠻ࡦࡄ࡞ࠬߩ㓸߹ࠅߢ޽ ࠆ߇‫߈ߣߩߎޔ‬ㆃᑧᤨ㑆ߦߟ޿ߡߪ㜞ዮ᛬₸ࠟ ࡜ࠬࡊ࡝࠭ࡓኻࠍ PCF ߩ಴ജㇱߦᝌ౉ߒߘߩ ⵬ఘࠍⴕ޿‫ࠅࠃߦࠇߎޔ‬ᐢᏪၞߢାภ߇㜞ᒝᐲ ߥ CARS ⸘᷹ࠍⴕ߁ߎߣ߇น⢻ߣߥߞߚ‫ޕ‬Fig 2 ߦߎࠇࠄࠍ↪޿ߡᓧࠄࠇߚන৻ࡐ࡝ࠬ࠴࡟ࡦ⃿ 㧔⋥ᓘ 6Pm㧕ߩ CARS ାภࠍ␜ߔ‫੹ޕ‬࿁ߩᡆૃ Fig 2 The CARS signal of a single polystyrene bead (black curve). The spontaneous Raman shifts are shown by dashed lines. ࠬ࡯ࡄ࡯ࠦࡦ࠹ࠖ࠾ࡘ࠙ࡓࠍ↪޿ߚᣇᴺߦࠃࠅ‫ޔ‬ ᓥ᧪ߩ⚂ 8 ಽߩ㧝ߩ 0.3 ⑽ߩ᷹ቯᤨ㑆ߢ 900 cm1 ߆ࠄ 3100 cm1 ߩᐢᏪၞߩ CARS ାภ߇᣿ ⍎ߦ᷹ⷰน⢻ߥߎߣ߇ࠊ߆ߞߚ‫ޕ‬ 㧙 101 㧙 ⎇ⓥᵴേ ࡈࠜ࠻࠾࠶ࠢ⚿᥏ࡈࠔࠗࡃ࡯߆ࠄߩ㜞ᰴࡕ࡯࠼ബ⿠ߦࠃࠆಽᢔᵄߩ ⊒↢ Generation of dispersive waves from a photonic crystal fiber by higher-order mode excitation ໊Ỉ⋥᮸㧔Naoki KARASAWA㧕 Tel & Fax: 0123-27-6063 E-mail: [email protected] Dispersive waves were generated from a photonic crystal fiber by higher-order mode excitation and the dependence of their wavelengths on polarization was measured. The dispersion properties of various spatial modes with different symmetry numbers were calculated theoretically and four combinations of linearly-polarizing higher-order modes were identified. The phase-matching conditions of dispersive waves for higher-order modes were calculated and it was found that the wavelengths of dispersive waves with identical spatial modes depended on polarization directions. The dependence measured experimentally agreed well with results obtained by theoretical calculations. ࡈࠜ࠻࠾࠶ࠢ⚿᥏ࡈࠔࠗࡃ࡯㧔PCF㧕ߦ⿥⍴శࡄ࡞ࠬࠍዉᵄߔࠆߣ⿥ᐢᏪၞశᵄࠍ⊒↢ߢ ߈ࠆߎߣ߇⷗಴ߐࠇ‫ޔ‬᭽‫ߥޘ‬ᔕ↪ߦ↪޿ࠄࠇߡ޿ࠆ‫⿥ޕ‬ᐢᏪၞశᵄߩ⊒↢ߪ PCF ߩಽᢔ߇ ബ⿠ᵄ㐳ߢ⇣Ᏹಽᢔߢ޽ࠅ‫ޔ‬㜞ᰴ࠰࡝࠻ࡦߩવ៝ߣߘߩၮᧄ࠰࡝࠻ࡦ߳ߩಽⵚ෸߮ၮᧄ࠰ ࡝࠻ࡦߣ૏⋧ᢛวߩߣࠇߚಽᢔᵄߩ⊒↢ߢ⺑᣿ߐࠇࠆ‫⎇ᧄޕ‬ⓥߦ߅޿ߡߪ㜞ᰴࡕ࡯࠼વ៝ ߦ߅޿ߡ߽ಽᢔᵄ߇⊒↢ߒ‫ߩߘޔ‬ᵄ㐳߇஍శᣇะߦଐሽߔࠆߎߣࠍ⷗಴ߒߚ‫ޕ‬ ᧄታ㛎ߢߪ⋥ᓘ߇ 1.57 Pm ߩⓨሹ߇ 6 ⷺᩰሶ⁁ߦࡇ࠶࠴߇ 2.27 Pm ߢ 5 ࡝ࡦࠣᒻᚑߐࠇߚ PCF ࠍ↪޿ߚ‫ߩࠄ߆࡯ࠩ࡯࡟ࠕࠗࠔࡈࠨࡦ࠲࠴ߦࠇߎޕ‬ᵄ㐳 810 nm‫ࠬ࡞ࡄޔ‬᏷ 50 fs ߩశࡄ ࡞ࠬࠍ౉኿ߐߖߚ‫ޕ‬ၮᧄࡕ࡯࠼વ៝ߢߪಽᢔᵄߩ⊒↢ߪ⷗ࠄࠇߥ߆ߞߚ߇‫ޔ‬㜞ᰴࡕ࡯࠼વ ៝ߢߪนⷞశߩ㗔ၞߦಽᢔᵄߩ⊒↢߇⷗ࠄࠇ‫ߩߘޔ‬ᵄ㐳ߪ஍శᣇะߦଐሽߒߚ‫ޕ‬Fig㧝ߦߘ ߩࠬࡍࠢ࠻࡞ࠍ␜ߔ‫ޕ‬ℂ⺰⸘▚ߦࠃࠅ㜞ᰴࡕ࡯࠼ߪⓨ㑆⊛ኻ⒓ᕈߩ⇣ߥࠆ㧠ߟߩࡕ࡯࠼㧔p1‫ޔ‬ p2‫ޔ‬p5‫ޔ‬p6㧕ߩ✢ᒻ⚿วߢ⴫ࠊߐࠇࠆߎߣ߇ࠊ߆ߞߚ‫ޕ‬ၮᧄ࠰࡝࠻ࡦࡄ࡞ࠬߣ૏⋧ᢛว߇ ߣࠇࠆߚ߼ߩಽᢔᵄߩᵄ㐳ࠍℂ⺰⊛ߦ⸘▚ߒߚ߽ߩࠍ Fig 2 ߦ␜ߔ‫ࠅࠃࠇߎޕ‬ห৻ߩⓨ㑆ࡕ ࡯࠼ࠍᜬߟ㜞ᰴࡕ࡯࠼ߦ߅޿ߡ‫ޔ‬஍శᣇะ߇⇣ߥࠆߣಽᢔᵄߩᵄ㐳⇣ߥࠆߎߣ߇੍᷹ߐࠇ‫ޔ‬ ታ㛎ߢߩ⚿ᨐ߇⺑᣿ߐࠇߚ‫ߦ߁ࠃߩߎޕ‬ಽᢔᵄߩᵄ㐳߇஍శᣇะߢ೙ᓮߢ߈ࠆߎߣ߆ࠄ‫ޔ‬ 㜞ㅦశᄌ⺞╬߳ߩᔕ↪߇⠨߃ࠄࠇࠆ‫ޕ‬ Fig 2 The dispersive wave wavelength versus pump wavelength for higher-order modes Fig 1 The spectra of dispersive waves and with different symmetry numbers. spatial modes. Arrows indicate polarization directions. ෳ⠨ᢥ₂㧦N. Karasawa and K. Tada, Opt. Express, 18, 5338 (2010). 㧙 102 㧙