{"product_id":"pockella-pockels-effect","title":"Pockella – The Pockels Effect \/ Δn ∝ E Physics Sticker","description":"\u003cp\u003ePockella, a grey-haired crystal-tamer, holds a glowing crystal between two electrodes with a beam passing through.\u003c\/p\u003e\u003ch3\u003eThe Physics\u003c\/h3\u003e\u003cp\u003eSome crystals without a centre of symmetry change their refractive index in direct proportion to an applied electric field. Friedrich Pockels studied this linear electro-optic effect in 1893. Put such a crystal between crossed polarisers and a voltage can switch light on and off in nanoseconds.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eΔn ∝ E\u003c\/strong\u003e\u003c\/p\u003e\u003cul\u003e\n\u003cli\u003eΔn: change in refractive index\u003c\/li\u003e\n\u003cli\u003eE: applied electric field (V\/m)\u003c\/li\u003e\n\u003c\/ul\u003e\u003cp\u003ePockels cells Q-switch lasers and modulate signals in optical communications.\u003c\/p\u003e\u003cp\u003e\u003cem\u003eHonest caveat:\u003c\/em\u003e Only non-centrosymmetric crystals show it; others show the weaker Kerr effect, Δn ∝ E². The exact coefficient depends on crystal axes.\u003c\/p\u003e\u003ch3\u003eOn the sticker\u003c\/h3\u003e\u003cp\u003ePockella holds a glowing cube crystal between two plates with a cyan beam running through it. Printed text: \u003cstrong\u003ePOCKELLA\u003c\/strong\u003e with the line \u003cstrong\u003eΔn ∝ E\u003c\/strong\u003e. Pixel-art kiss-cut vinyl sticker, white, in 2″, 3″, 4″ and 6″ sizes.\u003c\/p\u003e","brand":"Printify","offers":[{"title":"2\" × 2\" \/ White","offer_id":50964285816935,"sku":"21460775401026476199","price":4.99,"currency_code":"USD","in_stock":true},{"title":"3\" × 3\" \/ White","offer_id":50964285849703,"sku":"19239004653313360828","price":6.99,"currency_code":"USD","in_stock":true},{"title":"4\" × 4\" \/ White","offer_id":50964285882471,"sku":"25632497013160951779","price":8.99,"currency_code":"USD","in_stock":true},{"title":"6\" × 6\" \/ White","offer_id":50964285915239,"sku":"31730400128254866956","price":11.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0596\/8746\/9159\/files\/11979136540084753691_1200.jpg?v=1793664467","url":"https:\/\/pixelatedphysics.com\/it\/products\/pockella-pockels-effect","provider":"Pixelated Physics","version":"1.0","type":"link"}